Upload
may-smith
View
216
Download
0
Embed Size (px)
Citation preview
RADIOGRAPHY FOR DENTISTRY 1
DR.SAMY I AL-AGHAA PROFESSOR OF RADIOLOGY
AL-AZHAR UNIVERCITY
X-RAY IMAGE RECEPTORS
• 1-CONVENTIONAL X-RAY FILMS
• 2-DIGITAL IMAGE RECEPTORS
X-RAY FILM COMPOSITION
1-Film base2-Adhesive layer3-Film emulsion : a-Gelatin b-Silver halide crystals4-Protective layer
RADIOGRAPHIC FILM
FILM EMULSION
• SILVER HALIDES:1-AgBr2-Ag I3-Agcl
LATENT IMAGE
Ag Br + X-ray or light---Ag+ Br-(latent image)
CONVENTIONAL X-RAY FILMS
1-INTRA-ORAL FILMS
2-EXTRA-ORAL FILMS
INTRA-ORAL X-RAY FILMS
1-X-Ray film2- Two black papers3-Lead foil sheet4-Outer wrapping(soft packet) a-Tube side(white surface) b-Label side(colour coded)
KODAK PACKET COLOR CODES
One – film packet
Two-film packets
Ultra-speed(D-speed) GREEN GRAY
Ekta-speed(E-speed) BLUE PINK
TYPES OF INTRA-ORAL FILMS
1-PERIAPICAL FILMS
2-BITEWING FILMS
3-OCCLUSAL FILMS
PERIAPICAL FILMS
Size 0 :For children&adults with small mouth
Size 1: For anterior teeth in adultsSize 2:(standard film) For
anterior&posterior teeth in adults
BITE-WING FILMS
Size 0 For posterior teeth in young childrenSize 1 For posterior teeth in childrenSize 2 For posterior teeth in adults(most
frequent film)Size 3 For premolar or molar region
OCCLUSAL FILMS
Size 4: To show large areas of upper or lower jaw
FILM SPEED(SENSITIVITY)
It is exposure time necessary to produce an image on the film
Determined by 1-Size of silver halide crystals 2-Thickness of emulsion
Classified from A-speed(slowest) to F-speed(fastest)
FILM SPEED(SENSITIVITY)
Large crystals>>>High speed>>>less details
Small crystals>>>slow speed>>>More details
A-speed films>>>slowest speed &best detailsF-speed films>>>fastest speed &less details
EXTRA-ORAL FILMSTYPES : 1-Screen films 2-non screen filmsINDICATIONS: 1-PTS unable to open mouth2-view large area of pathology3-general view of mandible or maxilla4-view more bones of the face(skull or sinuses)5-impacted or unerupted teeth6-fractures of jaws&localization of F.B7-TM joint
INTENSIFYING SCREEN
COMPOSITION OF I. S.1-Plastic or cardboard sheet2-Reflecting layer (Titanium oxide)3-Phosphor layer: a-Ca Tungestate or Ba Ld sulfate(conventional
screen) b-Gd or Lanthanum (rare earth screen)
INTENSIFYING SCREEN
TYPESA-According to phosphor layer1-Conventional screen>>>Emit blue light
Kodak x-omatic screen 2-Rare earth screen >>> emit green light Kodak Lanex screen
INTENSIFYING SCREEN
B-ACCORDING TO SPEED (Crystal size)1-Slow : small crystals>>best image details
2-Intermediate : Larger crystals>> less details
3-Fast : Largest crystals >> Least details
CASSETTE HOLDERS
1-Cassette front :Plastic, cardboad or Alaminium2-Two Intensifying screens3- Film4-Felt padding5-Cassette back : Lead
FILM STORAGE
Avoid high temperature , chemical fumes , radiation & mechanical pressure
Proper storage conditions:1-Cool ,dry place (no humidity)2-No chemical fumes3-Lead lining of storage area4-Standing film boxes
DIGITAL RADIOGRAPHY
DISADVANTAGES OF CONVENTIONAL RADIOGRAPHY
1-Processing the films2-Use of high radiation dose3-The image cannot be changed4-Sensitive to variation in exposure5-Less sensitive to detect early osseous changes
DIGITAL RADIOGRAPHY
ADVANTAGES OF DIGITAL RADIOGRAPHY1-Low radiation dose2-Image manipulation>>adjust
contrast ,resolusion &image enhancement3-No processing4-Teleradiology5-Storage &archiving of patient imagings
DIGITAL RADIOGRAPHY
DISADVANTAGES OF DIGITAL RADIOGRAPHY1-Expensive2-Needs large disc spaces3-Electronic failure4-Difficult in intra-oral radiography
DIGITAL RADIOGRAPHY
1-Charge coupled device(CCD) systemComposed of a rare earth screen(in rigid plastic
casing)>>conical optical fibers &CCD>>display processing unit(DPU)
PRINSIPLE: X-ray photons strike the screen>>emits light>>transferred by optical fibers>>CCD>>Electrical signals>>digital signals by computer(A/D convertor)
DIGITAL RADIOGRAPHY
2-IMAGE PLATE (IP) SYSTEMCONSISTS OF phosphor particles embeded in a
polymer and coated on a plastic basePRINCIPLE:PHOTOSTIMULABLE LUMINESCENCESome of energy is stored in the screen>>latent
image>>electrical signals(by photomultiplier tubes)>>digital signals(by A/D converter)
FACTORS AFFECTING IMAGE
1-FACTORS RELATED TO X-RAY MACHINE
2-FACTORS RELATED TO OBJECT
3-FACTORS RELATED TO X-RAY FILM
FACTORS AFFECTING IMAGE
A-FACTORS RELATED TO X-RAY MACHINE1-KV2-MA3-EXP TIME(S)4-COLLIMATION5-FILTRATION6-SOURCE-OBJECT DISTANCE
FACTORS AFFECTING IMAGE
1-KV KV of dental x-ray machines from 65-90kv Increase KV(within normal range)>>X-ray high
energy photons >>more penetration power>>>>GOOD CONTRAST(differentiation between black ,white &gray shades
Optimal contrast is between65-90KV KV affects the quality of X-ray beam
FACTORS AFFECTING IMAGE2-mA
Normal mA of dental X-ray machines 8-12mA Increase mA (within normal range)>>increase heating
the filament>>increase No of X-ray photons>>increase degree of darkening of image(good or optimal DENSITY)
mA affects quantity of X-ray beam Difference in mA can be controlled by change of
exposure time(S )
FACTORS AFFECTING IMAGE
3-EXPOSURE TIME (S) Exposure= Ma X sec Affects quantity of X-ray beam
FACTORS AFFECTING IMAGE
4-COLLIMATION Good collimation >> restriction of x-ray beam >>decrease tissue exposure (safety of patients) Proper collimation >> decreases secondary
radiation&increases quality & sharpness of the image
FACTORS AFFECTING IMAGE
5-FILTRATION Filter is a thin sheets of AL which absorb weak x-
ray photons Thickness of AL sheets depends on KVp of x-ray
machines 1.5mm AL for KV up to 70 KVp 2.5mm AL for KV over 70 KVp Proper filtration improves quality of
beam>>patient safety &better image quality
FACTORS AFFECTING IMAGE
6-SOURCE-OBJECT DISTANCEINVERSE SQUARE LAW
FACTORS AFFECTING IMAGE
B-FACTORS RELATED TO OBJECT1-Atomic No2-Density3-Thickness of object
IMAGE CLARITY
SHARPNESS: It is a measure of how well the minimum details of object are seen on the radiograph
RESOLUTION: It is a measure of visualization small objects on the radiograph
END