Screening mammography a decade post-tomosynthesis: Varied utilization of synthetic mammography across a large health system.

Objectives: Digital breast tomosynthesis (DBT) with two-dimensional acquisition (2D) was approved in 2011 for breast cancer screening in the U.S. To reduce radiation dose to breasts, synthetic mammography (SM) was developed and approved to replace 2D with combo DBT in 2013. This retrospective study of screening practices in a large, incompletely integrated health system, assesses extent of SM utilization, and examines its impact on average glandular dose (AGD).

Methods: Consecutive screening exams on 61 mammography systems at nine hospitals from February 26 to March 12, 2023, were examined. Data collection included patient exams and radiation exposure. Comprehensive analysis included number of 2D acquisitions, three-dimensional (3D) views, breast thickness, and AGD. Comparative assessments were made across the health system cohort and individual hospitals. Statistical analysis was performed using the R statistical software (version 4.3.2).

Results: This study included 6849 screening exams on 13,484 breasts (thickness, 5.96 ± 1.47 cm) that received 3D views (13482/13484, or 99.99%) and 2D acquisitions (9459/13484, or 70.15%). For average breast thickness (about 6 cm), mean AGD per breast was 0.29-5.32 mGy (2D only), 4-6.1 mGy (3D only), and 5.5-9.94 mGy (2D/3D). Three hospitals preferentially used SM (81.3-93.5% of breasts). For an average breast, the ratio of mean AGD(3D) without 2D acquisitions to mean AGD(3D + 2D) with 2D acquisitions was 0.589 (95% CI: 0.561-0.619), 0.625 (0.563-0.702), and 0.588 (0.508-0.696), respectively.

Conclusions: Synthetic mammography reduces AGD. There is a need to review recurring screening mammographic exams and optimize patient doses by adopting synthetic mammography, where it meets the clinic's requirements.

Advances in knowledge: Synthetic mammography reduces average glandular dose by 36.5%, but only three of nine hospitals within the same large health system have adopted this technology. Breast centers should consider reviewing their imaging protocols to optimize radiation doses for patients undergoing annual screening mammography with synthetic mammography.