Comparison of radiation exposure and associated radiation-induced cancer risks from mammography and molecular imaging of the breast in a screening environment

Objectives To estimate and compare the risks of radiation-induced cancer from mammography and molecular imaging techniques such as Positron Emission Mammography (PEM), Breast Specific Gamma Imaging (BSGI) and Molecular Breast Imaging (MBI).

Methods The EAR and LAR models from the BEIR VII report were used to calculate the cumulative cancer mortality (CM) based on a population of 100,000 females followed from birth to age 80. Assuming annual screening from age 40-80 with each technology, the cumulative LAR from mammography (mean glandular dose range 3 mGy - 8 mGy), PEM (10 mCi F-18 FDG), and BSGI / MBI (dose range 20 mCi - 30 mCi Tc-99m sestamibi) was calculated. Organ dose for F-18 FDG and Tc-99m sestamibi was obtained from ICRP 80 and MIRD 19 reports. The cumulative CM in U.S. from all cancers and from breast cancer were computed from the National Program of Cancer Registries. Corrections were made for survival to a given age.

Results Over a 40 year screening period, mammography was estimated to result in a CM of 32-85 in 100,000 women. The normal cumulative CM for breast cancer in this population was calculated at 2138 cases. Assuming a 20-30% reduction in mortality from breast screening with mammography, this yielded 513-769 lives saved and a benefit / risk ratio of ~10:1. F-18 FDG resulted in a CM of 423 cases, and Tc-99m sestamibi (20-30 mCi) resulted in a CM of 380-570 cases. Assuming similar reduction in mortality from screening with PEM, BSGI or MBI would yield benefit / risk ratio of ~1:1.

Conclusions Administered doses of F-18 FDG and Tc-99m sestamibi need to be reduced to 1-2 mCi and 2-4 mCi respectively in order that molecular imaging techniques such as PEM, BSGI and MBI achieve a comparable benefit / risk ratio to that of mammography in a screening environment.

Research Support This work was supported in part by funding from Mayo Foundation and from the National Cancer Institute, grant CA128407