Evaluation of DR and CR digital mammography systems based on phantom and breast dosimetry

Digital mammography has been progressively introduced in screening centers, since recent evolution of CR and DR detectors. However, it is questionable which exposure conditions would be more suitable when these techniques are applied, in order to reduce the glandular breast doses, as they are related with induced carcinogenesis. Several exposures have been performed in CR and DR mammography units for comparing absorbed doses during quality control assessments and during screening, diagnosis and treatment. In the first case, the CIRS11A mammographic phantom has been used with standard exposure conditions (28 kV, AEC mode with blackening +0, 50:50 glandularity and 4.5 compressed breast thickness) in order to obtain reference values for the standard breast. After that, a sample population of 100 women per mammography unit has been registered for performing a dosimetry study during clinical conditions, using the SCREENDOSE software developed by the authors. Results show that there are significative differences among the mammography units, proving that this methodology could be used for obtaining an objective criterion during the selection of a mammography unit, related with a minimum image quality level for a given clinical use (screening, diagnosis or treatment).