Physical factors affecting the detection of calcifications in digital mammography

We are conducting a perception study to investigate the effects of detector design, magnification, and calcification size on the detection of calcifications in uniform as well as structured background. Calcium carbonate grains of various sizes were used to simulate calcifications. Three detectors were studied: a 100 mum aSi:H/CsI(TI) flat-panel system, a 30 mum CCD based system and an analog screen/film combination. The preliminary results show that the flat-panel system with a 100 mum pixel size outperformed a CCD based system with a 30 mum pixel size and an analog screen-film system. However, in studies with an anthropomorphic phantom as the background, the flat-panel system was outperformed by the other two systems. The presence of tissue structure background substantially reduced the calcification detectability. The use of geometric magnification generally improved the detectability with the exception of smallest and largest calcifications.