DOSE AND IMAGE QUALITY IN MAMMOGRAPHY WITH AN AUTOMATIC BEAM QUALITY SYSTEM

Radiation dose, contrast and image quality for automatic beam quality selection (OPDOSE) with the Siemens Mammomat 3000 has been investigate d for different breast thicknesses and compared with those found using manually set tube potentials and a molybdenum target and filter. Auto matic beam quality selection was found to have a negligible effect for breasts with a compressed breast thickness of less than 45 mm. Howeve r, for larger breasts substantial dose savings were achieved for a los s in contrast. For mammograms of compressed breasts with a thickness i n excess of 60 mm the mean glandular dose (MGD) per film was 2.90 mGy for manually selected tube potentials with a molybdenum/molybdenum tar get filter combination as compared with 1.87 mGy using 26 kVp and a tu ngsten target with rhodium filtration. The contrast loss in using OPDO SE was measured with a test object to be about 10% for breast thicknes ses in excess of 45 mm. The standard breast model, which assumes a 50% glandular content, did not provide a good fit to the MGD for women at tending for breast screening in the age range 50 to 64 years.