Program Information
CT Dose in Pregnancy: Organ Dose and Fetal Dose Under Various Gestational Ages and Maternal Sizes
W Fu*, P Segars , A Kapadia , E Samei , Duke University Medical Center, Durham, NC
Presentations
TH-EF-601-3 (Thursday, August 3, 2017) 1:00 PM - 3:00 PM Room: 601
Purpose: In utero radiation is a particular health issue due to the heightened potential risks to radiosensitive fetus and prenatal concerns. The purpose of this study was to estimate fetal dose and maternal patient organ doses under various gestational ages and maternal sizes.
Methods: A pregnant patient model was developed with fetuses at various gestational ages (3, 6, 8, 10, 15, 20, 25, 30, 35, and 38 weeks). The maternal model was obtained by deforming the 50ᵗʰ percentile XCAT adult female phantom to simulate the various stages of pregnancy. The fetus models were developed by segmenting fetus organs and structures from imaging data (CT, MRI, and histological). For fetuses at the 1st trimester, four other XCAT maternal models were included to represent various obesity classes (BMI: 18.21 underweight, 28.6 overweight, 30.66 class I obesity, 35.53 class II obesity). The fetal dose and maternal organ doses were estimated by Monte Carlo simulation of abdomen-pelvis and chest CT scans on a commercial CT scanner model.
Results: For chest scans, the fetal doses at 1st trimester were small, on average, at 0.2±0.2% of maternal lung doses. For abdomen-pelvis scans, the fetal doses were correlated with maternal body diameter with an exponential relationship. The fetal sizes significantly influenced the maternal patient organ doses, especially in pelvic region. The uterine dose increased by 1%, 16%, and 20% for phantoms with 6, 8, and 10 week fetuses, respectively, compared to the 3 weeks results. The fetal dose is more in line with maternal organ doses at lower gestational ages. The fetus has a strong influence on maternal organ doses at higher gestational ages.
Conclusion: For chest scans, the dose to 1st trimester fetuses is small. For abdomen-pelvis scans, it is feasible to characterize fetal dose using maternal body diameters.
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