Abstract
Mammography is an indispensable test for detecting early-stage breast cancer. In recommendations issued by the International Commission on Radiological Protection (ICRP) in 2007, the tissue-weighting factor was increased to 0.12 from the figure of 0.05 recommended in 1990. Research is therefore required to elucidate and optimize the dose received by patients during mammography. Most mammography devices incorporate automatic exposure control systems (AECs) to optimize dose and image quality. The aim of this study was to evaluate AECs at the same thickness and composition by using 80 mammography imaging devices (21 models made by seven manufacturers) currently in use, and to assess the dose received by patients during mammography in different institutions. AEC evaluation was performed by using a quality control 156 phantom and dose evaluation by using a polymethylmethacrylate phantom, and the average glandular dose was calculated from the irradiation conditions obtained. The results showed a 3.5-fold difference in average glandular dose, from 0.83 mGy to 2.90 mGy, when the 156 phantom was used. This rose to 4.38-fold for a 60-mm PMMA phantom. It was also shown that differences in dose arise from variations in pressure and detector position.
