Female Organ and Fetal Dose Estimates for Mammographic Exams
Abstract
Purpose
To evaluate sensitive organ and fetal doses for women undergoing mammography exams to determine potential risk and any justification for shielding.
Methods
An alpha version of The National Cancer Institute dosimetry system for Radiography and Fluoroscopy (NCIRF) program was used to setup the correct beam projections for craniocaudal (CC) and mediolateral (ML) conventional and tomosynthesis (15-degree sweep, 15 projections) mammography acquisitions. Mammographic spectra were generated in SpekPy and incorporated into the NCIRF source definition library. Due to the difficulty of modeling the breast support and detector in the lattice geometry, this initial study neglects this added attenuation.
Results
Key female adult organ and fetal organ doses were compared across the NCI adult female phantom and UF/NCI hybrid pregnant 38w in this study. When organ doses are normalized to a breast dose of 3 mGy (max expected breast dose for average breast thickness in clinical practice) female thyroid, lungs, effective dose, uterus dose (fetal dose surrogate for early pregnancy), and 38w GA fetal dose (2D) are all < 0.5 mGy/view (CC) and < 0.01 mGy/view (ML). Increased dose estimates for CC are due to the lack of breast support and detector attenuation, which is most pronounced with 38w 3D CC, as the fetus is partially in the primary beam for this view.
Conclusion
Even with the most conservative assumptions, and neglecting detector attenuation, female sensitive organ doses outside of the primary imaging field and fetal doses for (early GA) pregnant women undergoing mammography are less than any level that warrants risk discussion or patient shielding. Modeling of the breast support and detector as well as simulating the whole range of pregnant phantoms and exploring impact of breast thickness and higher energy acquisitions, like contrast enhanced mammography (CEM) is in progress.