Radiation dose reduction for augmentation mammography.

[OBJECTIVE] Patients who undergo cosmetic augmentation have larger and denser breasts and receive higher radiation doses during mammography than women without implants. In this study we evaluated the dose increase and techniques for dose reduction.

[SUBJECTS AND METHODS] Mean glandular dose to the breast during screening mammography was measured for 206 women who had undergone breast augmentation. For 13 of these women, mean glandular dose from preoperative mammography also was measured. Effective tube current, peak kilovoltage, and breast thickness were measured, and mean glandular dose was calculated for 1,632 images. Two screen-film combinations and three target-filter combinations were studied.

[RESULTS] For four-view augmentation mammography with a molybdenum-molybdenum (Mo-Mo) target-filter combination, mean glandular dose was reduced 35%, from 10.7 to 7.0 mGy, by changing the screen-film combination from 100 to 190 speed. For four-view augmentation mammography, mean glandular dose was reduced 24% by changing the target-filter combination from Mo-Mo to rhodium-rhodium (Rh-Rh) for full views of breasts containing implants. For four-view augmentation mammography, mean glandular dose was reduced 50% by changing the screen-film combination from 100 to 190 speed and changing the target-filter combination from Mo-Mo to Rh-Rh for implant-full views.

[CONCLUSION] Mean glandular dose per breast from four-view augmentation mammography with the 100-speed screen-film and Mo-Mo target-filter combinations averaged 10.7 mGy, which is 3.1 times higher than the 3.4 mGy for conventional two-view mammography of breasts without implants. In 40 years of screening, this number represents a more than tripled lifetime attributable risk of radiation-induced breast cancer--an unacceptable level. Use of faster screen-film combinations, use of Rh-Rh target-filter combinations, and acquisition of three rather than four views are dose-reduction methods that together result in a 66% dose reduction, from 10.7 to 3.6 mGy. Mean glandular dose should be kept less than 7.0 mGy per breast for screening mammography of patients with breast implants.