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Figure 5. Graph illustrates detection performance of the CAD system in 115 study cases of visible masses on prior mammograms, as a function of the false-positive mass marker rate. For comparison, the performance of the CAD system in the same cases but with use of the diagnostic mammograms, in which the cancers were detected later, also is shown. The difference in performance between the two sets of mammograms was due to the increased visibility of the cancers on the diagnostic images and the fact that most of the prior mammograms were only mediolateral-oblique views. In the observer study, we used only the CAD results obtained from the prior mammograms.