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Biokinetic model for 137Cs in the fetus
1Health Physics Program, G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332-0405, USA.
Health Physics
|November 5, 1997
Summary
Cesium-137 (137Cs) fetal and placental doses decrease throughout pregnancy. Biokinetic models predict lower radiation exposure to the fetus and placenta in later gestational periods.
Area of Science:
- Radiation dosimetry
- Biokinetics
- Pregnancy physiology
Background:
- Cesium (Cs) and potassium (K) are biologically similar elements.
- Pregnancy involves rapid placental and fetal growth, necessitating period-specific modeling.
- Existing biokinetic models for K informed Cs modeling.
Purpose of the Study:
- To estimate fetal and placental absorbed doses from Cesium-137 (137Cs) exposure during pregnancy.
- To develop physiologically based biokinetic models for K and Cs across four gestational periods.
- To assess radiation dose dynamics in the developing fetus and placenta.
Main Methods:
- Reviewed metabolic data for Cs and K in pregnant women.
- Developed physiologically based biokinetic models for K, adapted for Cs, for four gestational periods.
- Utilized medical internal radiation dosimetry to estimate absorbed doses to fetus and placenta from 137Cs.
- Assumed equilibrium between maternal and fetal plasma compartments.
Main Results:
- Fetal absorbed dose from 137Cs decreased from 1.3 x 10(-5) Gy Bq(-1) in early pregnancy to 8.3 x 10(-6) Gy Bq(-1) in late pregnancy.
- Placental absorbed dose also decreased as pregnancy progressed.
- Maternal organ 137Cs burdens were excluded from fetal dose calculations.
Conclusions:
- Radiation dose to the embryo/fetus and placenta from 137Cs exposure diminishes with advancing gestational age.
- Period-specific biokinetic modeling is crucial for accurate dosimetry in pregnancy.
- The study provides essential data for assessing radiation risks during pregnancy.