CONTRAST-DETAIL DETECTABILITY ANALYSIS - COMPARISON OF A DIGITAL SPOTMAMMOGRAPHY SYSTEM AND AN ANALOG SCREEN-FILM MAMMOGRAPHY SYSTEM

Rationale and Objectives. The authors compared the contrast-detail det ectability properties of an optically coupled charge-coupled device (C CD) digital mammography system with those of a conventional analog scr een-film mammography system. Methods. A proprietary contrast-detail ph antom was imaged with both systems, Twelve observers viewed analog and digital images obtained at seven different mean glandular doses. Cont rast-detail-dose curves were generated on the basis of the readers' vi sual perceptions. Interobserver errors were also calculated, In additi on, the authors applied a theoretical model for lesion detectability t o calculate and compare the digital and analog mammography systems, Re sults. The readers' contrast-detail detectability was significantly su perior with the digital system in the detail and contrast ranges evalu ated (P < .001). Conclusion. The performance of the readers paralleled the performance predicted by the theoretical model for the two imagin g systems, The following features account for the superior performance of the digital mammography system: (a) higher quantum efficiency of t he phosphor, (b) wider dynamic range, (c) better contrast transfer cha racteristics, and, most important, (ci) greater photon flux at the pho sphor entrance.