(Tuesday, 7/31/2018) 7:30 AM - 9:30 AM
Room: Room 202
Purpose: A prototype grating-based multi-contrast breast imaging system was recently developed in our laboratory based on a full-field digital mammography system (FFDM). The purpose of this work was to characterize the radiation dose performance of this prototype system through scatter radiation measurements and mean glandular dose (MGD) estimations.
Methods: To characterize whether the system modification leads to any additional scattered radiation to the patient, a Radcal 9095 exposure meter with a general-purpose ion chamber (10X6-6) was used to measure exposure levels at spatial positions corresponding to the patient chest wall and the breast. To estimate the MGD of multi-contrast image acquisitions, both the half value layer (HVL) and the entrance exposure at the surface of a ACR mammographic accreditation phantom (model 156) were measured for a total of four kV/filter combinations. The MGD was estimated using the method proposed by Dance et al.
Results: The measured (average [min., max.]) scattered radiation to the chest wall was 0.9 [0.2,2.2] mR for the prototype system, compared with 1.3 [0.6,2.1] mR for the original FFDM system. Backscatter to the breast due to the added gratings was negligible. For a 36 kVp, Rh filter, and 100 mAs multi-contrast image acquisition, the MGD was estimated to be 2.4 mGy. The MGD for other kV/filter combinations ranged from 4.7 to 8.8 µGy per mAs.
Conclusion: Compared to the original FFDM system, the prototype system does not increase scatter radiation to the chest wall due to the use of lead shielding surrounding the interferometer system and it introduces negligible backscatter radiation to the breast. For a typical multi-contrast imaging protocol of the prototype system, clinically-acceptable MGD levels can be maintained.
Funding Support, Disclosures, and Conflict of Interest: The work is partially supported by an NIH grant R01EB020521 and a DOD Breakthrough Award W81XWH-16-1-0031.
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