SU‐FF‐I‐37: A Comparison of Full‐Field Digital and Screen‐Film Mammography Dose

Abstract

Purpose: To determine whether mammograms acquired with a full‐field digital mammography (FFDM) unit using automatic exposure control (AEC) reduce patient radiation dose and exposure time as compared to screen‐film mammograms. Method and Materials: Exposure techniques and mean glandular dose (MGD) for FFDM and screen‐film mammography was compared for breast tissue equivalent attenuation slabs of varying thickness (2–8 cm) and glandular content (0–100%). FFDM images were acquired with a Lorad Selenia unit with AEC set to the manufacturer's recommended levels. Screen‐film mammograms were acquired with a Lorad M‐IV unit and Kodak Min‐R 2000 screen‐film system with AEC adjusted for an ACR accreditation phantom optical density of 1.8 OD. In addition, a patient survey including 150 mammograms compared the FFDM exposure techniques and MGD with the patient's corresponding screen‐film mammogram acquired 1 year prior. A 50% glandular tissue content was assumed. Results: For breast tissue equivalent attenuation slabs 4 cm thick or more, FFDM AEC was found to call for higher x‐ray beam energy exposures than screen‐film, resulting in lower MGD (mean 40%) and exposure time (mean 50%). Below 4 cm, FFDM kVp was lower than screen‐film, causing higher MGD (mean 15%) and exposure time (mean 20%). For the patient survey, FFDM resulted in a significantly lower MGD (mean 35%) and exposure time (mean 52%) than the corresponding screen‐film mammogram. Similar to the attenuation slabs, the FFDM dose and exposure time were generally higher than screen‐film for 2–4 cm compressed breast thickness and lower than screen‐film for 4 cm and above. Conclusion: FFDM using manufacturer's recommended dose settings results in significant dose reduction as compared to screen‐film mammography, particularly for 4 cm compressed breast thickness and above.