Hybrid Computational Phantoms of the Developing Fetus and Pregnant Femail: Construction and Application to Select Internal Radiation Dosimetry Studies

Date(s) - 07/18/2013
1:00 pm

Matthew Maynard, PhD student

The sensitivity of the human fetus to ionizing radiation is a well-documented issue.  Although not as immediately severe as other possible health effects, radiation-induced cancer remains an important health risk, particularly because radiation-induced cancers exhibit no lower dose threshold for exposures received in utero. Since cancer is an organ-level phenomenon, cases where it is induced by exposure to ionizing radiation require radiation dose estimates of affected tissues in order to mathematically quantify potential increases in risks.

One method to estimate fetal doses from in-utero exposures is through the use of computational simulation of the irradiation events using virtual replicas of the pregnant female and her child.  Advancements to the state-of-the-art in fetal computational radiation dosimetry were provided in this work through the development of anatomically-detailed computational phantoms representing the developing fetus and pregnant mother. Methods were developed for representing these complex geometries in modern radiation transport software, making it possible to assess fetal radiation doses from any type of definable radiation source.

Computational fetal and pregnant phantoms representing the Russian Urals population were also developed for the purposes of quantifying fetal radiation dose coefficients following the maternal and fetal uptake of hazardous radionuclides of interest to the European Union’s Epidemiological Studies of Exposed Southern Urals Populations (SOLO) project. A comprehensive set of intra-fetal and maternal cross-fire dose coefficients were calculated via computationally simulated internal radiation exposures.

Although intra-fetal dose coefficients to fetal targets were consistently several orders of magnitude greater than the maternal cross-fire contributions, several maternal source organs located near the developing fetus yielded significant variations in the calculated dose coefficients due to self-shielding of the fetus. The library of Urals-based radionuclide dose coefficients will be incorporated into the SOLO projects efforts to improve estimates of the risks of long-term health effects associated with protracted external and internal radiation exposures.