The local dense area (LDA) test is a test for evaluating the stability of image quality published in the EUREF fourth edition-supplements for local high-density areas. In this test, a small PMMA plate imitating LDA is placed on a rectangular PMMA, and the exposure conditions and SNR are evaluated when the thickness is changed. In this study, we replaced the rectangular PMMA with a D-shaped PMMA phantom-like breast. Then, we inserted an implant and a muscle phantom simulating the pectoral muscle and varied the distance from the edge of the chest wall to a small PMMA plate. In most of the tests, the SNR was stable as the thickness of the small PMMA plate increased as the exposure conditions increased. However, the SNR was not stable because the exposure conditions were not appropriate depending on the insertion distance of the muscle phantom and the position of the small PMMA plate.
Keywords: automatic exposure control (AEC); local dense area (LDA); mammography.