Comparison of digital and conventional mammography: a ROC study of 270 mammograms

Observer performance tests were conducted to study the visibility of malignancies in digital mammography. Detectabilities of tumours and of microcalcifications were studied separately. For this purpose two sets of images were used, one for tumours consisting of 150 mammograms and one for microcalcifications containing 120 mammograms. Images were digitized at a resolution of 2048 x 2048 pixels using a 12-bit CCD camera. Conventional film mammograms were read on a lightbox, whereas digital mammograms were viewed on a high-resolution monitor. Two experienced radiologists read both sets independently, and ranked their judgements about the presence or absence of tumours or microcalcifications on a confidence-rating scale. Results were evaluated using receiver operating characteristic (ROC) analysis. No statistical differences were found between judgements based on conventional and digitized mammography.