The purpose of the Film/Screen Contact lab was to test the contact between two different sizes of film with their respective screens. A 10"x12" cassette was placed on the table with a wire mesh tool against the receptor. The SID was set to 100cm and the collimation was adjusted to the size of the cassette. Exposure factors were set to 70kVp at 2mAs. The film was then processed in the dark room and viewed on the x-ray suite viewer box from 6 feet away. The procedure was then repeated with a 14"x17" cassette. The images were inspected for any wire tool irregularities and any localized blurring. The images were viewed in ambient lighting at 6 feet away in order to critique the image properly. Both of the images (as seen below) were good representations of the wire tool with no magnification or distortions. It is important that there is good contact between the film and the screen in order to make sure that the images taken are diagnostic and accurate representations of the anatomy imaged.
The contact could be disrupted by bent cassettes, scratches on the film, a foreign object inside of the cassette, incorrect storage temperature, dropping the cassette, moisture or warped screens. This would cause the image to be a misrepresentation of what is actually being imaged. The image could show magnification, distortions and blurring. It is important to check that the film/screen contact between the cassettes is still sufficient because it could cause a need for the patient to be re-exposed if it is noticed by the technologists that there is something wrong with the image. It could also cause a misdiagnosis if there is poor contact and it makes the image look like there is a pathology when there really isn't. In order to prevent film/screen contact problems from occurring, quality control habits are needed by each technologist. This includes making sure the film is stored properly, for example, keeping the film in a refrigerator to avoid moisture and to prolong the life of the film. Also making sure that cassettes are always handled with care when being used to avoid dropping of the cassette and causing poor film/screen contact. The technologist should be aware of what speed cassette they are using. A 400 speed cassette is more sensitive than a 100 speed cassette so it would be more susceptible to problems. If there was contact problems with a 400 speed film, the image would show the distortion more prominently. One more thing that should be monitored is the temperature of the developer. The developer should be at 35 degrees at all times in order to process the film properly.
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