SIMULATION OF MICROCALCIFICATION CLUSTERS IN DIGITAL MAMMOGRAPHY

Approximately 50%-70 % of malignant tumors in the breast are known to contain clusters of microcalcifications, which are small deposits of calcium compounds (mostly oxalates) varying in size from 100-400 microns1. In early stages of carcinoma, microcalcifications sometimes are the only signs of problems. It is therefore believed that discernability of cluster patterns in x-ray mammograms will serve as a marker for breast cancer in mammograms where the tumors themselves might not be convincingly visible. As a follow-up to our efforts at assessing the performance of new mammography modalities through image simulation by Monte Carlo, we are now studying the potential for imaging of microcalcification cluster patterns by a new digital mammography system, namely, the Fischer SenoscanTM. This study uses the MCMIS Monte Carlo code written and validated by one of the authors [DEP]. This code calculates images and dose for two different modalities, one of which is the SenoscanTM. The source of x rays is a high intensity x-ray tube operated typically at about 40 kVp. The low-energy photons are filtered out and the rest are collimated through a slot collimator to produce effectively a line source. The breast is compressed between two curved paddles and below it is a detector with a line CCD array. The collimator slot at the source and the detector scan across the breast to produce the digital radiograph of th