Contrast-detail detectability analysis: Comparison of a digital spot mammography system and an analog screen-film mammography system

Rationale and Objectives. The authors compared the contrast-detail detectability properties of an optically coupled charge-coupled device (CCD) digital mammography system with those of a conventional analog screen-film mammography system. Methods. A proprietary contrast-detail phantom was imaged with both systems, Twelve observers viewed analog and digital images obtained at seven different mean glandular doses. Contrast-detail-dose curves were generated on the basis of the readers' visual perceptions. Interobserver errors were also calculated, In addition, the authors applied a theoretical model for lesion detectability to calculate and compare the digital and analog mammography systems, Results. The readers' contrast-detail detectability was significantly superior with the digital system in the detail and contrast ranges evaluated (P < .001). Conclusion. The performance of the readers paralleled the performance predicted by the theoretical model for the two imaging systems, The following features account for the superior performance of the digital mammography system: (a) higher quantum efficiency of the phosphor, (b) wider dynamic range, (c) better contrast transfer characteristics, and, most important, (ci) greater photon flux at the phosphor entrance.