Individual doses in screening mammography examinations performed with digital equipment in Poland

Abstract

Background: The aim of this study was the estimation of individual doses for women participating in the mammography screening program in Poland, examined with digital systems. Material/Methods: Materials for this study included data obtained from 1800 exposures performed with the use of 9 different mammography units with digital systems. Exposure conditions (breast thickness after compression, high voltage, mAs value, the material of the anode and additional filter) were recorded during mammography screening examinations conducted for over one year in Poland. The collected data were used to determine individual doses in accordance with the method, which uses conversion factors for air kerma to the absorbed dose in the glandular tissue. The entrance air kerma for compressed breast exposure was determined on the basis of the measurements of the air kerma for the high-voltage value at which the exposure was performed, assuming a linear air kerma dependence on the tube load. Results: Individual doses established in 9 mammography facilities ranged from 0.40 mGy to 11.48 mGy for CR (computed radiography) systems and from 0.36 mGy to 5.80 mGy for DR (digital radiography) systems. The maximum value of the individual doses for CR systems was about 98% higher than for DR systems. The values of compressed breast thickness ranged from 2.0 cm to 7.6 cm for CR systems and from 2.1 cm to 11.4 cm for DR systems. The glandularity of breasts was from 9% to 100% for CR systems and from 3% to 97% for DR systems. The mean glandularity of breasts was 47% for CR systems and 29% for DR systems. Conclusions: One of the criteria for evaluating the suitability of digital systems in breast cancer screening in Poland should be the systematic evaluation of individual doses. In Poland, it is necessary to implement standardized methods of optimization of the exposure parameters for reducing individual doses to a minimum necessary to maintain the image quality