A plastic or metal film cassette holds and protects the extraoral film. during exposure, the side of the cassette must face the patient is the front side.
Film that is near fluorescent screens is on the film cassette. An interaction between the x-rays and the fluorescent-particle-coated screen takes place when the x-rays enter the film cassette. The fluorescent particles are made to emit light after being activated by x-rays. The photographic film is exposed by the light beams, and a picture is created. A film cassette and an x-ray tube are positioned between the patient. The x-ray tube emits x-rays, which travel through the body and are absorbed by bodily tissues.
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