Image receptors 2014.ppt

Image receptors

Priyankesh

1st year post graduate

department of oral medicine and radiology

CONTENT

INTRODUCTION

HISTORY

TYPES OF IMAGE RECEPTORS

Radiographic film

-direct action film

-indirect action film

Digital receptors

Conclusion

references

INTRODUCTION

• Image refers to picture or reflection of an object.• Receptor means anything that respond to a stimulus.• IMAGE RECEPTOR - a medium that changes X- ray beam into a visible image.

History

EARLY 1900 – glass plates wrapped in black paper

1913 – hand wrapped cellulose nitrate films

1924 – cellulose triacetate films

1960 – polyester base

1980 – digital radiography ( research and development)

1990 – CCD based imaging

2000 – only digital imaging

FIRST “FILM”GLASS PLATESCELLULOSE NITRATEHIGHLY FLAMMABLEEASILY TORNRESPONSIBLE FOR

MANY FIRES IN HOSPITAL BASEMENTS

CELLULOSE TRIACETATE

CLASSIFICATION OF X-RAY FILMS

• According to packaging

1. Single film packet

2. Double film packet• According to coating of emulsion

1. Single coated

2. Double coated

• According to sensitivity

1. Direct action / non-screen film

2. Indirect action / screen film• According to use

1. Intraoral films

2. Extra oral films

3. Duplicating films

4. Self developing film• According to speed of film

1. Slow speed film

2. Fast speed film

3. Hyper speed G

DIRECT/ NON-SCREEN FILM

• Wrapper – non absorbent paper or plastic or soft vinyl

- two sides

• Tube side – pebbled or smooth surface, usually white• Labeled side – usually two colors

INFORMATION ON LABELED SIDE:

- name of manufacturer

- number of films enclosed

- raised identification dot

- speed of the film

- statement regarding placement of film

COMPOSITION OF X –RAY FILM

• Base : transparent supporting material upon which emulsion is coated

Emulsion: Sensitive to X rays and visible light, records the radiographic

image.

• Film emulsion can be on one side or both sides of base

(single emulsion / double emulsion)

• Protective overcoat layered on top of emulsion

• Emulsion is a gelatin containing the film crystals

• Emulsion is the “active” layer of film

• Made of mixture of gelatin & silver halide crystals (fluorine, chlorine, bromine, & iodine)

Latent image

• A type of film that is used to make an identical copy of an intraoral or extraoral radiograph.

• Used only in darkroom setting

• Not exposed to x ray

• Emulsion is present on one side of the film

• Emulsion side – dull

• Non-emulsion side – shiny

• Does not have orientation dot

• Emulsion side of film must be in contact with radiograph to be duplicated

CASSETTE

CHARGED COUPLE DEVICE

Charge Coupled Devices (CCDs) were invented in October 19, 1969, by William S. Boyle and George

CCD

COMPLEMENTARY METAL OXIDE SEMICONDUCTORS

• Silicon-based semiconductors

• Electron hole pairs generated in pixels proportional to radiation dose

• Each pixel is isolated and directly connected to the transistor

• Transferred as a small voltage to transistor

• Transistors addressed separately, read by frame grabber

• Stored and displayed as a digital gray value

PHOTO STIMULABLE PHOSPHOR PLATES

• Photostimulable phosphor plates (PSP) absorb and store energy from x rays and then release this

energy as light (phosphorescence) when stimulated by other light of an appropriate wavelength.

• photostimulable phosphor material used for radiographic imaging is "Europium-doped" barium

fluorohalide..

FLAT PANEL DETECTORS

REFERENCES

• Oral radiology- principle and interpretation, -White and pharoah, 5th edition.

• Dental radiography, principles and techniques- Haring and jansen – 3rd edition