Radiation Dose to the Fetus for Pregnant Patients Undergoing Multidetector CT Imaging: Monte Carlo Simulations Estimating Fetal Dose for a Range of Gestational Age and Patient Size
- 1 October 2008
- journal article
- Published by Radiological Society of North America (RSNA) in Radiology
- Vol. 249 (1), 220-227
- https://doi.org/10.1148/radiol.2491071665
Abstract
Purpose: To use Monte Carlo simulations of a current-technology multidetector computed tomographic (CT) scanner to investigate fetal radiation dose resulting from an abdominal and pelvic examination for a range of actual patient anatomies that include variation in gestational age and maternal size. Materials and Methods: Institutional review board approval was obtained for this HIPAA-compliant retrospective study. Twenty-four models of maternal and fetal anatomy were created from image data from pregnant patients who had previously undergone clinically indicated CT examination. Gestational age ranged from less than 5 weeks to 36 weeks. Simulated helical scans of the abdominal and pelvic region were performed, and a normalized dose (in milligrays per 100 mAs) was calculated for each fetus. Stepwise multiple linear regression was performed to analyze the correlation of dose with gestational age and anatomic measurements of maternal size and fetal location. Results were compared with several existing fetal dose estimation methods. Results: Normalized fetal dose estimates from the Monte Carlo simulations ranged from 7.3 to 14.3 mGy/100 mAs, with an average of 10.8 mGy/100 mAs. Previous methods yielded values of 10–14 mGy/100 mAs. The correlation between gestational age and fetal dose was not significant (P = .543). Normalized fetal dose decreased linearly with increasing patient perimeter (R2 = 0.681, P < .001), and a two-factor model with patient perimeter and fetal depth demonstrated a strong correlation with fetal dose (R2 = 0.799, P < .002). Conclusion: A method for the estimation of fetal dose from models of actual patient anatomy that represented a range of gestational age and patient size was developed. Fetal dose correlated with maternal perimeter and varied more than previously recognized. This correlation improves when maternal size and fetal depth are combined. © RSNA, 2008Keywords
This publication has 16 references indexed in Scilit:
- Development of a 30‐week‐pregnant female tomographic model from computed tomography (CT) images for Monte Carlo organ dose calculationsMedical Physics, 2004
- A Monte Carlo-based method to estimate radiation dose from spiral CT: from phantom testing to patient-specific modelsPhysics in Medicine & Biology, 2003
- CT-Expo - ein neuartiges Programm zur Dosisevaluierung in der CTRöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2002
- AAPM/RSNA Physics Tutorial for Residents: Topics in CTRadioGraphics, 2002
- Fetal position and size data for dose estimation.The British Journal of Radiology, 1999
- A CT‐based Monte Carlo simulation tool for dosimetry planning and analysisMedical Physics, 1998
- Estimated fetal radiation dose from multislice CT studies.American Journal of Roentgenology, 1990
- The calculations of dose from external photon exposures using reference and realistic human phantoms and Monte Carlo methodsPhysics in Medicine & Biology, 1986
- A method for describing the doses delivered by transmission x-ray computed tomographyMedical Physics, 1981
- Estimates of absorbed fractions for monoenergetic photon sources uniformly distributed in various organs of a heterogeneous phantom.1969