Image quality, dose, and quality control in screen-film and full-field digital mammography.

摘要

The purpose of this work is to measure and compare the current state of equipment performance of screen-film mammography (SFM) and full-field digital mammography (FFDM). There are three distinct projects including: (1) the evaluation of screen-film systems in Colorado, (2) optimizing technique factors for FFDM and comparing them to FSM under the constraint of matched patient dose, and (3) technical comparison of the first clinical FFDM units in the United States to FSM.; Medical physics testing was performed at participating sites in the Colorado Mammography Advocacy Project (CMAP) to assess breast dose, image quality, and trends in equipment performance over the last decade. Between December 1989 and October 1999, 216 on-site physics surveys were performed. In 1989--90, 21 units at 18 CMAP facilities were surveyed. In 1999, 38 units at 25 CMAP facilities were surveyed. Results indicate that mammography image quality has improved significantly over the last decade. Despite significant improvements, however, there are still wide ranges of image quality and dose in the practice of mammography.; Contrast-detail image analysis was performed to optimize technique factors for detection of low-contrast lesions using a silicon diode array FFDM system under the conditions of matched mean glandular dose for a given breast thickness across the full range of compressed breast thicknesses. The FFDM results are then compared to SFM at each breast thickness. The results indicate that low-contrast detection was optimized for FFDM by using a softer x-ray beam for thin breasts and a harder x-ray beam for thick breasts when MGD was kept constant.{09}Under this constraint, optimized FFDM CD scores were superior to SFM CD scores for all but the thinnest breasts.; Results of acceptance testing 18 FFDM systems for clinical use and of conducting annual physics surveys of 38 SFM systems were compared in terms of exposure times, mean glandular breast doses, and image quality. Results indicate that the clinical use of digital mammography may generally improve image quality for equal or lower breast doses, while providing tighter control on exposures and image quality than screen-film mammography.