Digital Radiography

1GOOD AFTERNOON

DIGITAL RADIOGRAPHY

BY DR REVATH VYAS DEVULAPALLI

Digital Radiography

2

ContentDigital Radiography

3

Introduction amp History

Equipment

Digital Image acquisitionbull Types of receptor

bull CCDbull CMOSbull Flat panel detectorsbull PSP

ContentDigital Radiography

4

Digital Image ProcessingDigital Radiographic Image StorageDigital Image CommunicationAdvantage and Disadvantages ndash OverallConclusion

Introduction Since the discovery of X-rays in 1895 film has

been the primary medium for capturing displaying and storing radiographic images

It is a technology that dental practitioners are the most familiar and comfortable with in terms of technique and interpretation

Digital radiography is the latest advancement in dental imaging and is slowly being adopted by the dental profession

Digital Radiography

5

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Introduction Digital imaging incorporates computer

technology in the capture display enhancement and storage of direct radiographic images

Digital imaging offers some distinct advantages over film but like any emerging technology it presents new and different challenges for the practitioner to overcome

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The Journal of Contemporary Dental Practice 2002 3(4)1-13

Digital Radiography

7Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

A conventional system uses x-ray film to create a latent image

The film is then processed creating a manifest image that can be interpreted by a physician

It is later stored in the file room (physical storage for archival)

Digital Radiography

8

Method is film-based

Method may uses intensifying screens

Film is placed between two screens

Screens emit light when x-rays strike them

Film is processed chemically

Processed film is viewed on view-box (lightbox)

Digital Radiography

9

Digital Radiography

10

Chemical Processing in film radiography

Problems with Film

10 of films are not available when we want them

15 of films are ldquohardrdquo to locate or find 25 of films are ldquomisplacedrdquo or not retrievable

(misfiled) 10 of films are lost (referrals residents etc) Recent study ndash physicians spend two weeksyear

(100 hoursyear) trying to locate or find the films they need

Digital Radiography

11

Digital Radiography

12Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

Digital imaging or Digitization

Digital Imaging is any modality method of imaging that creates an image that can be viewed or stored on a computer

Digital Radiography

13

Pixel

In digital imaging a pixel [picture element] is the smallest controllable element of a picture represented on the screen

Digital Radiography

14

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

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White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

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White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

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White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

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White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

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White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

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White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

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Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

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Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

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60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

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69

Disadvantages

Large in size so cannot be used intraorally Expensive

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70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

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StructureDigital Radiography

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Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

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White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

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Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

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Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

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White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

DIGITAL RADIOGRAPHY

BY DR REVATH VYAS DEVULAPALLI

Digital Radiography

2

ContentDigital Radiography

3

Introduction amp History

Equipment

Digital Image acquisitionbull Types of receptor

bull CCDbull CMOSbull Flat panel detectorsbull PSP

ContentDigital Radiography

4

Digital Image ProcessingDigital Radiographic Image StorageDigital Image CommunicationAdvantage and Disadvantages ndash OverallConclusion

Introduction Since the discovery of X-rays in 1895 film has

been the primary medium for capturing displaying and storing radiographic images

It is a technology that dental practitioners are the most familiar and comfortable with in terms of technique and interpretation

Digital radiography is the latest advancement in dental imaging and is slowly being adopted by the dental profession

Digital Radiography

5

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Introduction Digital imaging incorporates computer

technology in the capture display enhancement and storage of direct radiographic images

Digital imaging offers some distinct advantages over film but like any emerging technology it presents new and different challenges for the practitioner to overcome

Digital Radiography

6

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Digital Radiography

7Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

A conventional system uses x-ray film to create a latent image

The film is then processed creating a manifest image that can be interpreted by a physician

It is later stored in the file room (physical storage for archival)

Digital Radiography

8

Method is film-based

Method may uses intensifying screens

Film is placed between two screens

Screens emit light when x-rays strike them

Film is processed chemically

Processed film is viewed on view-box (lightbox)

Digital Radiography

9

Digital Radiography

10

Chemical Processing in film radiography

Problems with Film

10 of films are not available when we want them

15 of films are ldquohardrdquo to locate or find 25 of films are ldquomisplacedrdquo or not retrievable

(misfiled) 10 of films are lost (referrals residents etc) Recent study ndash physicians spend two weeksyear

(100 hoursyear) trying to locate or find the films they need

Digital Radiography

11

Digital Radiography

12Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

Digital imaging or Digitization

Digital Imaging is any modality method of imaging that creates an image that can be viewed or stored on a computer

Digital Radiography

13

Pixel

In digital imaging a pixel [picture element] is the smallest controllable element of a picture represented on the screen

Digital Radiography

14

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

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StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

ContentDigital Radiography

3

Introduction amp History

Equipment

Digital Image acquisitionbull Types of receptor

bull CCDbull CMOSbull Flat panel detectorsbull PSP

ContentDigital Radiography

4

Digital Image ProcessingDigital Radiographic Image StorageDigital Image CommunicationAdvantage and Disadvantages ndash OverallConclusion

Introduction Since the discovery of X-rays in 1895 film has

been the primary medium for capturing displaying and storing radiographic images

It is a technology that dental practitioners are the most familiar and comfortable with in terms of technique and interpretation

Digital radiography is the latest advancement in dental imaging and is slowly being adopted by the dental profession

Digital Radiography

5

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Introduction Digital imaging incorporates computer

technology in the capture display enhancement and storage of direct radiographic images

Digital imaging offers some distinct advantages over film but like any emerging technology it presents new and different challenges for the practitioner to overcome

Digital Radiography

6

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Digital Radiography

7Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

A conventional system uses x-ray film to create a latent image

The film is then processed creating a manifest image that can be interpreted by a physician

It is later stored in the file room (physical storage for archival)

Digital Radiography

8

Method is film-based

Method may uses intensifying screens

Film is placed between two screens

Screens emit light when x-rays strike them

Film is processed chemically

Processed film is viewed on view-box (lightbox)

Digital Radiography

9

Digital Radiography

10

Chemical Processing in film radiography

Problems with Film

10 of films are not available when we want them

15 of films are ldquohardrdquo to locate or find 25 of films are ldquomisplacedrdquo or not retrievable

(misfiled) 10 of films are lost (referrals residents etc) Recent study ndash physicians spend two weeksyear

(100 hoursyear) trying to locate or find the films they need

Digital Radiography

11

Digital Radiography

12Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

Digital imaging or Digitization

Digital Imaging is any modality method of imaging that creates an image that can be viewed or stored on a computer

Digital Radiography

13

Pixel

In digital imaging a pixel [picture element] is the smallest controllable element of a picture represented on the screen

Digital Radiography

14

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

ContentDigital Radiography

4

Digital Image ProcessingDigital Radiographic Image StorageDigital Image CommunicationAdvantage and Disadvantages ndash OverallConclusion

Introduction Since the discovery of X-rays in 1895 film has

been the primary medium for capturing displaying and storing radiographic images

It is a technology that dental practitioners are the most familiar and comfortable with in terms of technique and interpretation

Digital radiography is the latest advancement in dental imaging and is slowly being adopted by the dental profession

Digital Radiography

5

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Introduction Digital imaging incorporates computer

technology in the capture display enhancement and storage of direct radiographic images

Digital imaging offers some distinct advantages over film but like any emerging technology it presents new and different challenges for the practitioner to overcome

Digital Radiography

6

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Digital Radiography

7Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

A conventional system uses x-ray film to create a latent image

The film is then processed creating a manifest image that can be interpreted by a physician

It is later stored in the file room (physical storage for archival)

Digital Radiography

8

Method is film-based

Method may uses intensifying screens

Film is placed between two screens

Screens emit light when x-rays strike them

Film is processed chemically

Processed film is viewed on view-box (lightbox)

Digital Radiography

9

Digital Radiography

10

Chemical Processing in film radiography

Problems with Film

10 of films are not available when we want them

15 of films are ldquohardrdquo to locate or find 25 of films are ldquomisplacedrdquo or not retrievable

(misfiled) 10 of films are lost (referrals residents etc) Recent study ndash physicians spend two weeksyear

(100 hoursyear) trying to locate or find the films they need

Digital Radiography

11

Digital Radiography

12Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

Digital imaging or Digitization

Digital Imaging is any modality method of imaging that creates an image that can be viewed or stored on a computer

Digital Radiography

13

Pixel

In digital imaging a pixel [picture element] is the smallest controllable element of a picture represented on the screen

Digital Radiography

14

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Introduction Since the discovery of X-rays in 1895 film has

been the primary medium for capturing displaying and storing radiographic images

It is a technology that dental practitioners are the most familiar and comfortable with in terms of technique and interpretation

Digital radiography is the latest advancement in dental imaging and is slowly being adopted by the dental profession

Digital Radiography

5

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Introduction Digital imaging incorporates computer

technology in the capture display enhancement and storage of direct radiographic images

Digital imaging offers some distinct advantages over film but like any emerging technology it presents new and different challenges for the practitioner to overcome

Digital Radiography

6

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Digital Radiography

7Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

A conventional system uses x-ray film to create a latent image

The film is then processed creating a manifest image that can be interpreted by a physician

It is later stored in the file room (physical storage for archival)

Digital Radiography

8

Method is film-based

Method may uses intensifying screens

Film is placed between two screens

Screens emit light when x-rays strike them

Film is processed chemically

Processed film is viewed on view-box (lightbox)

Digital Radiography

9

Digital Radiography

10

Chemical Processing in film radiography

Problems with Film

10 of films are not available when we want them

15 of films are ldquohardrdquo to locate or find 25 of films are ldquomisplacedrdquo or not retrievable

(misfiled) 10 of films are lost (referrals residents etc) Recent study ndash physicians spend two weeksyear

(100 hoursyear) trying to locate or find the films they need

Digital Radiography

11

Digital Radiography

12Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

Digital imaging or Digitization

Digital Imaging is any modality method of imaging that creates an image that can be viewed or stored on a computer

Digital Radiography

13

Pixel

In digital imaging a pixel [picture element] is the smallest controllable element of a picture represented on the screen

Digital Radiography

14

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Introduction Digital imaging incorporates computer

technology in the capture display enhancement and storage of direct radiographic images

Digital imaging offers some distinct advantages over film but like any emerging technology it presents new and different challenges for the practitioner to overcome

Digital Radiography

6

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Digital Radiography

7Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

A conventional system uses x-ray film to create a latent image

The film is then processed creating a manifest image that can be interpreted by a physician

It is later stored in the file room (physical storage for archival)

Digital Radiography

8

Method is film-based

Method may uses intensifying screens

Film is placed between two screens

Screens emit light when x-rays strike them

Film is processed chemically

Processed film is viewed on view-box (lightbox)

Digital Radiography

9

Digital Radiography

10

Chemical Processing in film radiography

Problems with Film

10 of films are not available when we want them

15 of films are ldquohardrdquo to locate or find 25 of films are ldquomisplacedrdquo or not retrievable

(misfiled) 10 of films are lost (referrals residents etc) Recent study ndash physicians spend two weeksyear

(100 hoursyear) trying to locate or find the films they need

Digital Radiography

11

Digital Radiography

12Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

Digital imaging or Digitization

Digital Imaging is any modality method of imaging that creates an image that can be viewed or stored on a computer

Digital Radiography

13

Pixel

In digital imaging a pixel [picture element] is the smallest controllable element of a picture represented on the screen

Digital Radiography

14

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

7Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

A conventional system uses x-ray film to create a latent image

The film is then processed creating a manifest image that can be interpreted by a physician

It is later stored in the file room (physical storage for archival)

Digital Radiography

8

Method is film-based

Method may uses intensifying screens

Film is placed between two screens

Screens emit light when x-rays strike them

Film is processed chemically

Processed film is viewed on view-box (lightbox)

Digital Radiography

9

Digital Radiography

10

Chemical Processing in film radiography

Problems with Film

10 of films are not available when we want them

15 of films are ldquohardrdquo to locate or find 25 of films are ldquomisplacedrdquo or not retrievable

(misfiled) 10 of films are lost (referrals residents etc) Recent study ndash physicians spend two weeksyear

(100 hoursyear) trying to locate or find the films they need

Digital Radiography

11

Digital Radiography

12Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

Digital imaging or Digitization

Digital Imaging is any modality method of imaging that creates an image that can be viewed or stored on a computer

Digital Radiography

13

Pixel

In digital imaging a pixel [picture element] is the smallest controllable element of a picture represented on the screen

Digital Radiography

14

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

A conventional system uses x-ray film to create a latent image

The film is then processed creating a manifest image that can be interpreted by a physician

It is later stored in the file room (physical storage for archival)

Digital Radiography

8

Method is film-based

Method may uses intensifying screens

Film is placed between two screens

Screens emit light when x-rays strike them

Film is processed chemically

Processed film is viewed on view-box (lightbox)

Digital Radiography

9

Digital Radiography

10

Chemical Processing in film radiography

Problems with Film

10 of films are not available when we want them

15 of films are ldquohardrdquo to locate or find 25 of films are ldquomisplacedrdquo or not retrievable

(misfiled) 10 of films are lost (referrals residents etc) Recent study ndash physicians spend two weeksyear

(100 hoursyear) trying to locate or find the films they need

Digital Radiography

11

Digital Radiography

12Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

Digital imaging or Digitization

Digital Imaging is any modality method of imaging that creates an image that can be viewed or stored on a computer

Digital Radiography

13

Pixel

In digital imaging a pixel [picture element] is the smallest controllable element of a picture represented on the screen

Digital Radiography

14

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Method is film-based

Method may uses intensifying screens

Film is placed between two screens

Screens emit light when x-rays strike them

Film is processed chemically

Processed film is viewed on view-box (lightbox)

Digital Radiography

9

Digital Radiography

10

Chemical Processing in film radiography

Problems with Film

10 of films are not available when we want them

15 of films are ldquohardrdquo to locate or find 25 of films are ldquomisplacedrdquo or not retrievable

(misfiled) 10 of films are lost (referrals residents etc) Recent study ndash physicians spend two weeksyear

(100 hoursyear) trying to locate or find the films they need

Digital Radiography

11

Digital Radiography

12Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

Digital imaging or Digitization

Digital Imaging is any modality method of imaging that creates an image that can be viewed or stored on a computer

Digital Radiography

13

Pixel

In digital imaging a pixel [picture element] is the smallest controllable element of a picture represented on the screen

Digital Radiography

14

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

10

Chemical Processing in film radiography

Problems with Film

10 of films are not available when we want them

15 of films are ldquohardrdquo to locate or find 25 of films are ldquomisplacedrdquo or not retrievable

(misfiled) 10 of films are lost (referrals residents etc) Recent study ndash physicians spend two weeksyear

(100 hoursyear) trying to locate or find the films they need

Digital Radiography

11

Digital Radiography

12Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

Digital imaging or Digitization

Digital Imaging is any modality method of imaging that creates an image that can be viewed or stored on a computer

Digital Radiography

13

Pixel

In digital imaging a pixel [picture element] is the smallest controllable element of a picture represented on the screen

Digital Radiography

14

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Problems with Film

10 of films are not available when we want them

15 of films are ldquohardrdquo to locate or find 25 of films are ldquomisplacedrdquo or not retrievable

(misfiled) 10 of films are lost (referrals residents etc) Recent study ndash physicians spend two weeksyear

(100 hoursyear) trying to locate or find the films they need

Digital Radiography

11

Digital Radiography

12Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

Digital imaging or Digitization

Digital Imaging is any modality method of imaging that creates an image that can be viewed or stored on a computer

Digital Radiography

13

Pixel

In digital imaging a pixel [picture element] is the smallest controllable element of a picture represented on the screen

Digital Radiography

14

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

12Radiography

Analog Digital

Scanner (X-ray

digitizer)

Computed Radiography

(CR)

Direct Digital

Radiography (DR or DDR)

Digital imaging or Digitization

Digital Imaging is any modality method of imaging that creates an image that can be viewed or stored on a computer

Digital Radiography

13

Pixel

In digital imaging a pixel [picture element] is the smallest controllable element of a picture represented on the screen

Digital Radiography

14

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital imaging or Digitization

Digital Imaging is any modality method of imaging that creates an image that can be viewed or stored on a computer

Digital Radiography

13

Pixel

In digital imaging a pixel [picture element] is the smallest controllable element of a picture represented on the screen

Digital Radiography

14

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Pixel

In digital imaging a pixel [picture element] is the smallest controllable element of a picture represented on the screen

Digital Radiography

14

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

PixelDigital Radiography

15

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

PixelDigital Radiography

16

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiPixel

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Analogue to Digital Conversion

The term digital in digital imaging refers to the numeric format of the image content and its discreteness

Conventional film images can be considered an analog medium in which differences in the size and distribution of black metallic silver result in a continuous density spectrum

Digital Radiography

17

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Analogue to Digital Conversion

Digital images are numeric and discrete in two ways(1) in terms of the spatial distribution of the picture elements (pixels) and (2) in terms of the different shades of gray of each of the pixels

Digital Radiography

18

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Analogue to Digital Conversion

A digital image consists of a large collection of individual pixels organized in a matrix of rows and columns

Production of a digital image requires a process called analog to digital conversion (ADC)

Digital Radiography

19

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

ADC consists of 2 steps

Quantization

SamplingDigital Radiography

20

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Sampling Sampling means that a small range of

voltage values are grouped together as a single value

Digital Radiography

21

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Sampling Narrow sampling better

mimics the original signal but leads to larger memory requirements for the resulting digital image

Digital Radiography

22

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Quantization

Once sampled every sampled signal is assigned a value

For the clinician to see the image the computer organizes the pixels in their proper locations and displays a shade of gray that corresponds to the number that was assigned during the quantization step

Digital Radiography

23

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Quantization Digital Radiography

24

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

EquipmentAn x-ray machine Digital image receptorbull a sensor

An analog-to-digital converter Computer and monitorbull with appropriate hardware software network

connectionPrinter

Digital Radiography

25

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

26

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

Direct Indirect

Digital Radiography

27

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Direct digital imagingDigital Radiography

28

Sensor placed in ptrsquos mouth

Exposed to

radiation

Sensor captur

es radiographic

image

Transmit

image to a

computer

monitor

Image appear

s on screen within second

s

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Indirect digital imaging

Exisiting Xray film digitized

using CCD camera

Scans the image

Digitizes displays on computer monitor

Digital Radiography

29

The Journal of Contemporary Dental Practice 2002 3(4)1-13

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Types of digital image receptorDigital Radiography

30

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

1 Solid state technologybull Charge coupled devicebull Complementory metal oxide

semiconductorsbull Flat panel detectors

2 Photostimulable phosphor plate

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital image receptorsDigital Radiography

31

Solid State Technology

Uses semi-conductor based detectors

1 CCD2 CMOS

3 Flat PanelLanccedila L Silva A Digital Imaging Systems for Plain

Radiography Springer 2013

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Charge coupled device

Introduced in 1987 1st intraoral digital receptor Consist of thin wafer of silicon with electronic

circuit Consist of matrix amplifier in plastic houisng

Digital Radiography

32

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

A number of manufacturers produce detectors with varying active sensor areas roughly corresponding to the different sizes of intraoral film

Digital Radiography

33

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

34

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

StructureDigital Radiography

35

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

StructureDigital Radiography

36

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Exposure to radiation

Break the covalent bond in silicon atoms

Produce electron hole pair

Electron attracted towards most positive potential in device ndash create charge packetCharge pattern formed from individual pixels forms latent image

Digital Radiography

37

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

38

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Valence Band

MechanismDigital Radiography

39

+e-

e-

Photoelectric absorption in Silicon

Conduction Band

e-+

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

40

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

41

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

42

[Internet] [cited 2014 Apr 10] Available from httpwwwvikdhillonstaffshefacukteachingphy217det

ectors

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

43

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

44

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

45

>

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Bucket brigade form of charge transferFinally transferred to amplifier

Transmitted as voltage

Analog to digital converter

Image display

Digital Radiography

46

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

47

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

CCD Detectors without flaws are relatively expensive to

produce and expense of the detector increases with increasing matrix size (total number of pixels)

Pixel size varies from 20 microns to 70 microns Smaller pixel size increases the cost of the receptor

CCDs have also been made in linear arrays of a few pixels wide and many pixels long for panoramic and cephalometric imaging

Digital Radiography

48

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

49

CCD Linear array

made up of few px wide and many px long

Area array

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Linear arrayDigital Radiography

50

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Area arrayDigital Radiography

51

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

AdvantagesDigital Radiography

52Intact images or real time image production and displayConsistent quality

X ray sensitivity is 80 greater than conventional filmElimination of hazardous chemicals used in film processing and lead foilComputer aided diagnosis

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

DisadvantagesDigital Radiography

53

High initial cost of system

Unknown life expectancy of CCD sensor

Rigidity and thickness of the sensor

Decreased resolution

CCDS cannot be sterilized

Hard copy images fade with time

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

DisadvantagesDigital Radiography

54

Image manipulation can be time consuming

The sensor may not be well tolerated by patients -more time-consuming

The cable attached to the sensor is easily damaged and may interfere with sensor

Actual area available for image capture may be as little as 60 of the sensor area

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Complementary metal oxide semiconductors Digital Radiography

55

Each pixel is isolated from its neighboring pixels and connected to

transistorElectron hole pair generated within

pixelCharge transfer to transistor in form

of voltageEach transistor voltage is read out

separately by frame grabberStored and displayed as digital gray

value

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

56

ADC

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

57

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Scintillator

A scintillator is a material that exhibits scintillation mdash the property of luminescence when excited by ionizing radiation

Luminescent materials when struck by an incoming particle absorb its energy and scintillate (ie re-emit the absorbed energy in the form of light)

Digital Radiography

58

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiScintillator

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

59

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

These sensors do not require charge transfer resulting in increased sensor reliability and lifespan

Require less system power to operate and are less expensive to manufacture

Low cost Fixed pattern of noise Smaller active area

Digital Radiography

60

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

CCD CMOS POWER

COSUMPTION 400mw 40mw

SENSITIVITY TO LIGHT

Excellent Excellent

SENSITIVITY TO X RAYS

High Unknown

PIXEL SIZE 40 micron 25 micron COST High Medium MANUFACTURE Expensive Cheap BREAKAGE

RESISTANCE Low Medium

DYNAMIC RANGE Excellent Excellent NOISE Low High READOUT Complex Simple EFFICACY Excellent Fair

Digital Radiography

61

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Flat panel detector

Used for medical imaging extraoral imaging device

Provide large matrix area with pixel of less than 100 microm

Allows imaging of larger areas including head 2 types direct indirect

Digital Radiography

62

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Flat panel detectorDigital Radiography

63Indirect flat panel detector

sensitive to visible light

use intensifying screen to convert X-ray to lightPhotoconductor material - aSi

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Flat panel detectorDigital Radiography

64Direct flat panel detector use

selenium for efficient X-rays absorption

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Flat panel detector

It is a ldquosandwichrdquo constructions consisting of a scintillator layer an amorphous silicon photodiode circuitry layer and a TFT array

Digital Radiography

65

White SC Pharoah MJ Oral Radiology Principles and Interpretation

6th Edition Mosby 2009

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Thin Film Transistor (TFT)

It is a special kind of field-effect transistor made by depositing thin films of an active semiconductor layer

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power It is composed of semiconductor material with at least three terminals for connection to an external circuit

Digital Radiography

66

[Internet] [cited 2014 Apr 10] Available from httpenwikipediaorgwikiThin-film_transistor

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Flat panel detector

When x-ray photons reach the scintillator visible light proportional to the incident energy is emitted and then recorded by an array of photodiodes and converted to electrical charges

These charges are then read out by a TFT array similar to that of direct conversion DR systems

Digital Radiography

67

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Flat Panel StructureDigital Radiography

68

Lanccedila L Silva A Digital Imaging Systems for Plain Radiography Springer 2013

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Advantages

Real-time process With a time lapse between exposure and

image display of less than 10 seconds

Digital Radiography

69

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Disadvantages

Large in size so cannot be used intraorally Expensive

Digital Radiography

70

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Photostimulable phosphor plates Also known as storage phosphor

plates (spp) image plates or computed radiography

Flexible wireless indirect receptors

Available in the same sizes as intraoral films

Digital Radiography

71

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Structure

The PSP material used for radiographic imaging is ldquo europium dopedrdquo barium fluorohalide

Barium in combination with iodine chlorine or bromine forms a crystal lattice

The addition of europium (Eu + 2 ) creates imperfections in this lattice

Digital Radiography

72

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

StructureDigital Radiography

73

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Mechanism

When exposed to a sufficiently energetic source of radiation valence electrons in europium can absorb energy and move into the conduction band

These electrons migrate to nearby halogen vacancies (F-centers) in the fluorohalide lattice and may become trapped there in a metastable state

Digital Radiography

74

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Valence Band e-

Plate prepared

Plate exposed

X ray photon

F Center

Eu+2 Eu+3Eu+2

F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Mechanism

While in this state the number of trapped electrons is proportional to x-ray exposure and represents a latent image

When stimulated by red light of around 600 nm the barium fluorohalide releases trapped electrons to the conduction band

Digital Radiography

76

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Mechanism

When an electron returns to the Eu + 3 ion energy is released in the green spectrum between 300 and 500 nm

Digital Radiography

77

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Valence Bande-

Plate prepared

Plate exposed

Plate processed

lase

r

Phot

omul

tipl

ier

tub

e

X ray photon

F Center

Eu+2 Eu+3

Eu+2 Eu+3Eu+2

F Center F Center

Conduction Band

Whaites E

Essentials of Dental Radiograp

hy and Radiology

4th edition 2007

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Mechanism

Fiberoptics conduct light from the PSP plate to a photomultiplier tube

The photomultiplier tube converts light into electrical energy A red filter at the photomultiplier tube selectively removes the

stimulating laser light and the remaining green light is detected and converted to a varying voltage

Digital Radiography

79

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

PROCEDUREDigital Radiography

80

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

PROCEDUREDigital Radiography

81

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Stationary plate scans

Method for reading the latent images on PSP plates A rapidly rotating multifaceted mirror that reflects a beam of red

laser light As the mirror revolves the laser light sweeps across the plate

The plate is advanced and the adjacent line of phosphor is scanned

Digital Radiography

82

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Slow scan direction ndash direction of psp plate Fast scan direction ndash direction of laser light

Digital Radiography

83

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Rotating plate scans

Rapidly rotating drum that holds the plate Consist of Rotation of drum and fixed laser

Digital Radiography

84

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Advantages

Storage phosphor plates can be reused indefinitelyReceptor is cordless amp flexibleLinear or logarithmic response to radiation is availableThere is wide exposure range amp fewer retakesLess radiation is required

Digital Radiography

85

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

AdvantagesDigital Radiography

86

No chemical processing required

Image processing of acquired images is available

Images can be transferred to easily

Images can be easily amp inexpensively stored amp retrieved

Computed aided diagnosis

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

DisadvantagesReceptors must be erased before reuse

High initial cost of the equipment

The spatial resolution of film exceeds

Some of the image processing routines are time ndash intensive

Phosphor plates must be packaged in sterile envelopes

possibility of transfer of contaminated material to patients mouth if integrity of plates protective envelope is jeopardized

Digital Radiography

87

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Imaging processing Any operation that acts to improve restore

analyze or in some way change a digital image is a form of image processing

Some of these operations are integrated in the image acquisition and image management software and are hidden from the user

Others are controlled by the user with the intention to improve the quality of the image or to analyze its contents

Digital Radiography

88

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Imaging processingDigital Radiography

89

Image restoration

Image enhancement

Image analysis

Image compression

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Image restoration

Raw data enter computer Preprocessing -- Image corrected for known

defects Adjustment of image intensities Substitution of defective pixels

Preprocessing operations set by manufacturer

Digital Radiography

90

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Image restoration

Depending on the quality of the sensor and the choices made by the manufacturer a variety of other operations maybe applied to the image before it becomes visible on the display

They are executed very rapidly and are unnoticed by the user

Digital Radiography

91

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Imaging processingDigital Radiography

92

Image restoration

Image enhancement

Image analysis

Image compression

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

BrightnessDigital Radiography

93

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

ContrastDigital Radiography

94

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Negative Conversion

Useful in visualizing the trabecular pattern of bone pulp canal and chamber anatomy

Digital Radiography

95

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

96

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

97

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Colour Digital Radiography

98

Whaites E Essentials of Dental Radiography and Radiology 4th edition 2007

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Imaging processingDigital Radiography

99

Image restoration

Image enhancement

Image analysis

Image compression

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

100

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

b) Diagnosis

Three basic steps of image analysis are Segmentation - most critical step Feature extraction Object classification

The goal of segmentation is to simplify the image and reduce it to its basic components

This involves subdividing the image thus separating objects from the background

Digital Radiography

101

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

b) Diagnosis

Objects of interest are defined by the diagnostic task for example a tooth a carious lesion a bone level or an implant

A unique set of values for a certain combination of features can lead to classification of the object

Automated cephalometric landmark identification is an example

Digital Radiography

102

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Dental subtraction radiography (Ruttimann et al 1981) was found to be a feasible method that increases the accuracy of detection of density changes between serial radiographs

Digital Radiography

103

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

When two images of the same object are registered and the image intensities of corresponding pixels are subtracted a uniform difference image is produced

If there is a change in the radiographic attenuation between the baseline and follow-up examination this change shows up as a brighter area when the change represents gain and as a darker area when the change represents loss

Digital Radiography

104

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

The strength of digital subtraction radiography (DSR) is that it cancels out the complex anatomic background against which this change occurs

Subtraction radiography requires two images which are exposed with the same geometry

Digital Radiography

105

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

106

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Imaging processingDigital Radiography

107

Image restoration

Image enhancement

Image analysis

Image compression

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Image compression

Process of file reduction To reduce computer storage space and

facilitate image retrieval and transmission Compression becomes a more important issue

as the number of patient records and image files to be stored increases over time

Two types lossless and lossy

Digital Radiography

108

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

109

LOSSLESS LOSSYDonot discard any image data

Discard image data

Maximum compression rate lt 31

Range from 121 to 281

More memory to manipulate

Less memory

Retrieval and transmission slow

quick

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Laser PrinterDigital Radiography

110

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Image Storage The use of digital imaging in dentistry requires an

image archiving and management system that is very different from conventional radiography

Storage of diagnostic images on magnetic or optical media raises a number of new issues that must be considered

The file size of dental digital radiographs varies considerably ranging from 200 KB for intra oral images to as much as 6 MB for extraoral images

Digital Radiography

111

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Image Storage

Once in a digital format critical image data can be deleted or modified

The backup media suitable for external storage of digital radiographs include external hard drives digital types CDs and DVDs

Digital Radiography

112

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

COMMON PROBLEMS IN DIGITAL IMAGING

1 Noisy Images2 Non uniform image density3 Distorted Images4 Double Images

Digital Radiography

113

White SC Pharoah MJ Oral Radiology Principles and Interpretation 6th Edition Mosby 2009

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Noisy ImagesDigital Radiography

114

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

2Non uniform image densityDigital Radiography

115

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

3 Distorted ImagesDigital Radiography

116

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

4 Double ImagesDigital Radiography

117

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Damaged Image receptors

Scratched phosphor surface mimicking root canal filling A and retake B

Digital Radiography

118

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Image artifacts resulting from excessive bending of the PSP plate and excessive bending has resulted in permanent damage to the phosphor plate

Digital Radiography

119

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

PSP circular artifact as a result of plate damage and localized swelling of the protective coating from disinfectant solution on work surface

Digital Radiography

120

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

PSP image artifact resulting from plate surface contamination

This artifact was caused by a glove powder smudge that prevented proper scanning of the affected area of the PSP plate

Digital Radiography

121

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Malfunctioning CCD sensor resulting from rough handling (dropped sensor)

The sensor produces geometric image artifacts

Digital Radiography

122

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Improper use of image processing tools such as filters may result in false-positive findings An edge enhancement filter was applied to the panoramic image which produced radiolucencies at restoration edges simulating recurrent caries

These radiolucencies are not present in a follow-up intraoral image

Digital Radiography

123

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

124

Imaging Step Film CCDCMOS PSP

Receptor preparation None

1) Place protective plastic sleeve over receptor

2) Receptor must be connected to computer and patient identifying information entered for acquisitionarchiving software

1) Erase plates2) Package plates

in protective plastic envelope

Receptor placement

1)Film holding devices2) Film may be bent to accommodate anatomy

1) Specialised receptor holder

2) Inflexible and bulkiness

3) Receptor cable4) Discomfort

1) Film holding devices

2) Bending of receptor may irreversibly damage it

ExposureSimple exposure

Computer must be activated before

exposure

Simple exposure

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Digital Radiography

125

Imaging Step Film CCDCMOS PSP

Processing

1) Dark room2) Processing

chemicals3) Processing

time4) Hazardous

wastes

Image acquisation and display is almost immediate

1) Dim light envt2) Processor must be

programmed with patient and detector information so that images are identified preprocessed and stored properly

Display Preparation

Film mounts 1) Software ndash digital mount

1) Individual mount2) Digitally rotated

Display

1) A room with subdued lighting and a masked viewbox

2) Any light source

1) subdued lighting 2) A computer and display with app Software3) Size of the display restrict the no of images

Image Duplication

Inferior to original and sometimes non-diagnostic

1 Electronic copies may be stored on variety of media without loss of image quality

2 Output on Film or paper is inferior and non-diagnostic

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

ADVANTAGES OF DIGITAL IMAGING

Digital Radiography

126

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Dose reduction Dose reductions of up to 90 per cent compared

to E speed film have been reported by some authors in the diagnosis of caries

Although some researchers do claim dose reductions compared with conventional extra-oral film in practice the background noise rises to unacceptable levels

It is now accepted that there is no appreciable reduction compared with films used in conjunction with rare earth intensifying screens

Digital Radiography

127

Dentomaxillofacial Radiology 1995 24 250

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Image manipulation

This is perhaps the greatest advantage of digital imaging over conventional film

It involves selecting the information of greatest diagnostic value and suppressing the rest

Manufacturers provide software programmes with many different processing tools however some are more useful than others and these include

Digital Radiography

128

Dentomaxillofacial Radiology 201241(3)203-210

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

1 Contrast enhancement

This can effectively compensate for over or under exposure of the digital image

It has been shown that contrast enhancement of CCD devices were more accurate than E-speed film for detecting simulated caries under orthodontic bands

Digital Radiography

129

The British Journal of Radiology 199164(763)591-595

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

2 Measurements Digital callipers rulers and protractors are

some of the many tools available for image analysis

Many authors have reported on their application in cephalometric analysis

The images can also be superimposed onto each other and onto digital photographs

Digital Radiography

130

Journal of Endodontics 2007 33(1) 1ndash6

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

3 3-D reconstruction

This application can be theoretically used to reconstruct intra- and extra-oral images

The uses range from profiling root canals to visualizing facial fractures in all three dimensions

Digital Radiography

131

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

4 Filtration

The addition of filters to the airspace around the face can clarify the soft tissue profile if the original soft tissue image was poor

Digital Radiography

132

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Time

Much time is gained especially with the CCD system where the image is displayed at the chairside immediately post exposure

Although a lag time between scanning and the appearance of an image exists with the PSP method it is still substantially faster than conventional developing processes in general use

Digital Radiography

133

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Storage

Storage was initially a problem before the development of DVDs and CD ROMs as three peri-apical images would fill a floppy disc

However now a CD ROM can hold over 30000 images

This means that images can be stored cheaply and indefinitely

Digital Radiography

134

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Teleradiology

Teleradiology is the transmission of radiological patient images such as x-rays CTs and MRIs from one location to another for the purposes of sharing studies with other radiologists and physicians

This had the advantages of not losing radiographs in the post and saving time if an urgent appointment is required

Digital Radiography

135

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Environmentally friendly

No processing chemicals are used or disposed of Both CCD sensors and the PSP plates are capable of being reused for many thousands of exposures

They can however become scratched and damaged if not handled carefully

Digital Radiography

136

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Medico-legal Many insurance companies in the USA are

accepting digital images as valid attachments when the claims are electronically claimed

Digital Radiography

137

Dentomaxillofacial Radiology 2000 12(4)292-297

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

DISADVANTAGES OF DIGITAL IMAGING

Digital Radiography

138

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

CostCurrently the cost of

Intra oral sensor ndash 12 ndash 2 lakhExtra oral machins ndash 10 - 15 lakh

Digital Radiography

139

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Sensor dimensions

These are still quite bulky for the CCD system and awkward to position due to trailing fibre optic wires

The original problem of small sensor active areas has been rectified and the same amount of information can be captured as conventional film

Digital Radiography

140

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Cross-infection control

Each intra-oral sensor and plate must be covered by a plastic bag and this bag is changed between patients

However if they become directly contaminated there is no way of sterilizing them and they should be discarded regardless of expense

Digital Radiography

141

Brennan J Journal of Orthodontics 2002 (29) 66ndash69

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Medico-legal

Concerns have been raised in the past about the ability to manipulate the images for fraudulent purposes

Manufacturers of software programmes have installed lsquoaudit trailsrsquo which can track down and recover the original image

Digital Radiography

142

Dentomaxillofacial Radiology 2000 12(4)292-297

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Conclusion The technology is now available to run a practice almost

paper free It is theoretically possible to store clinical notes

photographs radiographs and study models on disc and refer or consult online

Research is also continuing into the development of a credit card sized lsquosmart cardrsquo which could carry a patientrsquos medical and dental notes along with their radiographic images

It is important that advances in technology are accepted and the benefits that they produce utilized in order that clinical practice and patient care continue to improve

Digital Radiography

143

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip

Thank YouhellipDigital Radiography

144

• GOOD AFTERNOON
• DIGITAL RADIOGRAPHY
• Content
• Content (2)
• Introduction
• Introduction (2)
• Slide 7
• Slide 8
• Slide 9
• Slide 10
• Problems with Film
• Slide 12
• Digital imaging or Digitization
• Pixel
• Pixel (2)
• Pixel (3)
• Analogue to Digital Conversion
• Analogue to Digital Conversion (2)
• Analogue to Digital Conversion (3)
• ADC consists of 2 steps
• Sampling
• Sampling (2)
• Quantization
• Quantization (2)
• Equipment
• Slide 26
• Slide 27
• Direct digital imaging
• Indirect digital imaging
• Types of digital image receptor
• Digital image receptors
• Charge coupled device
• Slide 33
• Slide 34
• Structure
• Structure (2)
• Slide 37
• Slide 38
• Mechanism
• Slide 40
• Slide 41
• Slide 42
• Slide 43
• Slide 44
• Slide 45
• Slide 46
• Slide 47
• CCD
• Slide 49
• Linear array
• Area array
• Advantages
• Disadvantages
• Disadvantages (2)
• Complementary metal oxide semiconductors
• Slide 56
• Slide 57
• Scintillator
• Slide 59
• Slide 60
• Slide 61
• Flat panel detector
• Flat panel detector (2)
• Flat panel detector (3)
• Flat panel detector (4)
• Thin Film Transistor (TFT)
• Flat panel detector (5)
• Flat Panel Structure
• Advantages (2)
• Disadvantages (3)
• Photostimulable phosphor plates
• Structure (3)
• Structure (4)
• Mechanism (2)
• Slide 75
• Mechanism (3)
• Mechanism (4)
• Slide 78
• Mechanism (5)
• PROCEDURE
• PROCEDURE (2)
• Stationary plate scans
• Slide 83
• Rotating plate scans
• Advantages (3)
• Advantages (4)
• Disadvantages (4)
• Imaging processing
• Imaging processing (2)
• Image restoration
• Image restoration (2)
• Imaging processing (3)
• Brightness
• Contrast
• Negative Conversion
• Slide 96
• Slide 97
• Colour
• Imaging processing (4)
• Slide 100
• b) Diagnosis
• b) Diagnosis (2)
• Slide 103
• Slide 104
• Slide 105
• Slide 106
• Imaging processing (5)
• Image compression
• Slide 109
• Laser Printer
• Image Storage
• Image Storage (2)
• COMMON PROBLEMS IN DIGITAL IMAGING
• Noisy Images
• 2Non uniform image density
• 3 Distorted Images
• 4 Double Images
• Damaged Image receptors
• Slide 119
• Slide 120
• Slide 121
• Slide 122
• Slide 123
• Slide 124
• Slide 125
• ADVANTAGES OF DIGITAL IMAGING
• Dose reduction
• Image manipulation
• 1 Contrast enhancement
• 2 Measurements
• 3 3-D reconstruction
• 4 Filtration
• Time
• Storage
• Teleradiology
• Environmentally friendly
• Medico-legal
• DISADVANTAGES OF DIGITAL IMAGING
• Cost
• Sensor dimensions
• Cross-infection control
• Medico-legal (2)
• Conclusion
• Thank Youhellip