Sensitometric evaluation of some mammographic film-screen combinations

The rapid expansion of screening and assessment mammography is due in part to recent advances in film and processing technology. This has been facilitated by the achievement of high contrast images at lower radiation dose levels. One of the recognised keys for this advancement has been the adoption of extended processing times when compared to regular radiographic processing. The role of other factors, including film types and development chemistry, have received less attention to the present, but is becoming increasingly important as mammographic film technology progresses. This paper reports on four locally available mammographic films that have been exposed through film screen systems to ascertain sensitometric parameters for a variety of processing conditions. Three development times were used (23, 32 and 42 seconds) in combination with four development temperature (32, 34, 36 and 38 degrees) for each of four different chemistries. The results indicate that, as expected, development temperature and time play a major role in film contrast and speed. They also show, however, that different film types respond very differently to extended development times and that development chemistries can be critical to optimal film performance.