X-RAY Films and Processing - Focus Dentistry

X RAY FILMS AND PROCESSING

X-ray film is composed of BASE and EMULSION.

BASE	EMULSION	LEAD FOIL
Polyester polyethelene terephthalate	Silver bromide + Silver iodide crystals in a vehicle of gelatin. The function of silver iodide is to increase the sensitivity og AgBr crystals to x rays.	Kept on the backside of film away from the tube Shields the film from back scattered radiation. Absorbs scattered photons and reduces the film fog, thus increases image quality. It also reduces the patient exposure by absorbing the residual xray beam. If the film is reversed, it results in a light image with characteristic HERRING BONE OR EMBOSSED pattern on the radiograph.

SIZE OF X RAY FILMS
IOPA X RAY
Size 0	22×35mm	For small children
Size 1	24×40mm	For anterior projections
Size 2	32×41mm	Standard film size for adults
BITEWING FILM
Size 0	22×35mm	Very small children
Size 1	24×40mm	Children
Size 2	32×41mm	Adults
Size 3	37×54mm	Long size bitewing film
OCCLUSAL FILMS	4 times larger than the size 2 film	52×76mm
SCREEN FILMS	8×10 inches	For extraoral projections along with the intensifying screens

DARK ROOM PROCESSING OF A RADIOGRAPH

STAGE	PURPOSE	TIME
WETTING	Alkaline developing solution softens and opens up gelatin so that developing agents can act on silver halide crystals.	30 sec
STAGE1: DEVELOPMENT	The sensitized silver halide crystals in the emulsion are converted to black metallic silver to produce the black part of the image	4-5 min
STAGE 2: WASHING	The film is washed in water to remove residual developer solution	15 sec
STAGE 3: FIXATION	The unsensitized silver halide crystals in the emulsion are removed to reveal the transparent and white parts of the image and the emulsion is hardened.	8-10 min
STAGE 4: WASHING	The film is washed thorougly in running water to remove residual fixer solution	15-20 min
STAGE 5: DRYING	The resultant black/ white grey radiograph is dried	30 min

Automatic processors have the same time cycle as manual process. Usually if the time of developing is X , then the minimum time of fixing is 2X.

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