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

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