Figure 8. Free-response ROC curves show the performance of the CAD scheme for clinically important (
5 mm) polyps. The curves were generated by moving the dividing line in Figure 6b from the lower right corner to the upper right corner while maintaining the slope of the line and regarding the possible polyps above and below the line as false- and true-positive, respectively. The solid curve represents the performance of the scheme on the basis of results of CT colonography in 41 patients. A polyp was regarded as detected if it was detected on either the supine or the prone view. The dashed curve represents the performance of the scheme on the basis of 82 CT colonographic volumetric data sets. Polyps and false-positive findings on supine and prone views were counted independently.