Converting One Set of Mammograms to Simulate a Range of Detector Imaging Characteristics for Observer Studies

A methodology for adjusting mammographic images taken on a given imaging system to simulate their appearance if taken on a different system for use in observer studies is presented. The process involves adjusting the image sharpness and noise, which takes into account the detector, breast thickness, and beam quality. The method has been tested by converting images acquired using an a-Se detector of a CDMAM test object and 'Rachel' anthropomorphic breast phantom. They were degraded to appear as if acquired using a computed radiography (CR) detector. Good agreement was achieved in the resulting threshold gold thickness for the simulated CR images with measured real values for CDMAM images. Power spectra comparisons of real and simulated images of the 'Rachel' phantom agree with an average difference of 4%. This tool in conjunction with observer studies can be used to understand the effects of the detector characteristics on cancer detection in mammography.