Workload and transmission data for the installation of a digital breast tomosynthesis system
- Division of Diagnostic Imaging Physics and Webster Center for Advanced Research and Education in Radiation, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States)
Purpose: Digital breast tomosynthesis (DBT) differs from conventional mammography in target/filter, kVp range, and imaging geometry. The aim of this study was to assess the breast input exposure of a DBT system by completing a workload survey of DBT installations, and to determine the parameters {alpha}, {beta}, and {gamma} in the Archer equation for the primary radiation generated by the clinical workload distributions. Methods: The authors conducted a retrospective survey of the x-ray breast imaging performed between September 2011 and September 2012 in three clinical DBT rooms equipped with Selenia Dimensions systems (Hologic Inc., Bedford, MA). A total of 343 examinations were analyzed to calculate the workload (mA-minute) and the primary air kerma at 1 m from the source (K{sup 1}). Transmission curves were calculated for the primary radiation generated by the workload distributions of the DBT rooms, and were fitted to the Archer equation. Results: There were large variations in patient volume and workload in the three examination rooms. In all these rooms, the average tube voltage (kVp) was about 31, the average K{sup 1} per patient was 16-21 mGy, and the average mA-minute per patient was 1.4-2.2 times higher than that of the mammography room described in NCRP Report No. 147. Most DBT screening examinations consisted of four two-dimensional mammographic views plus four tomosynthesis scans; the numbers of views acquired in diagnostic examinations varied widely. Tomosynthesis scans contributed about 30% of total mA-minute and about 50% of K{sup 1}. For the primary radiation generated by the clinical workload distributions, {alpha} was similar to that of 40-45 kVp W/Al (target/filter), and {alpha}+{beta} was similar to that of 30 kVp W/Al. Conclusions: The workload (mA-minute and K{sup 1}) distributions of mammographic examinations with DBT differ from conventional mammography. A field survey of patient volume and x-ray tube usage is important for the shielding design of DBT facilities. The clinical workloads and transmission data presented in this paper may be useful for clinical medical physicists.
- OSTI ID:
- 22121037
- Journal Information:
- Medical Physics, Vol. 40, Issue 6; Other Information: (c) 2013 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-2405
- Country of Publication:
- United States
- Language:
- English
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