Quality control in mammography. 2. communication

A test specimen was developed which allows to determine the parameters optical density, contrast, useful radiation field, and dose, and with which it is also possible to control the development of the film. Constancy tests were carried through with this test specimen, over a period of about 6 months at intervals of approximately two weeks, on eleven mammography units subjected to a previous check. The results show variations (substantial in part) to arise especially from the film development and to bear - correspondingly - on optical density (and contrast). Therefore controls of film development at close intervals - where possible daily - seem recommendable for mammography. By contrast variations of the characteristic quantities were rare (one mammography unit had a malfunciton of the automatic exposure timer); this suggests that X-ray images of the test specimen repeated monthly should be sufficient. (orig./MG)