[Average glandular tissue dose and image quality in screen-film mammography]

We investigated the relationship between average glandular tissue dose and imaging properties such as image density, contrast, and visual image quality, varying the tube voltage and subject parameters (glandular fraction and breast thickness) The wax inserts of 156 phantom and disk of polymethyl methacrylate (PMMA) were arranged between the BR-12 breast-equivalent phantoms. These phantoms were radiographed using automatic exposure control (AEC) for the various combinations of tube voltage and subject parameters. In addition, exposures were measured at the same time. The results showed that the average glandular tissue dose increased when the high glandular fraction and/or thick phantom were being radiographed with the low tube voltage. We found that the criteria of the Japanese Mammography Screening Accreditation Program for image quality were not satisfied when breast thickness was greater than 6 cm.