Caywood K, Ice R, Hertel N
Health Physics Program, G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332-0405, USA.
Health Phys. 1997 Nov;73(5):736-46. doi: 10.1097/00004032-199711000-00001.
The metabolic data for cesium and the biologically similar element potassium in the pregnant woman were reviewed. Due to the rapid growth of the placenta and fetus, the pregnancy was divided into four gestational periods: five through ten weeks, eleven through twenty weeks, twenty-one through thirty weeks, and thirty-one through forty weeks. A physiologically based biokinetic model for potassium was developed for each of these periods. This model was used as a basis for the cesium model. The models consisted of several organs, all of which involved recycling and for which it was assumed that equilibrium existed between the uterus and maternal plasma and the fetal organs and fetal plasma. The absorbed dose to the fetus and placenta was estimated from 137Cs located in the fetus and placenta using medical internal radiation dosimetry methodology. The dose to the embryo/ fetus was 1.3 x 10(-5) Gy Bq(-1) during the first gestational period and decreased to 8.3 x 10(-6) Gy Bq(-1) for the final period. The dose to the placenta also decreased as the pregnancy progressed. 137Cs located in the maternal organs was not accounted for when determining the fetal dose estimates.
对孕妇体内铯以及生物特性与之相似的元素钾的代谢数据进行了回顾。由于胎盘和胎儿的快速生长，孕期被分为四个阶段：五至十周、十一至二十周、二十一至三十周以及三十一至四十周。针对每个阶段建立了基于生理学的钾生物动力学模型。该模型被用作铯模型的基础。这些模型由多个器官组成，所有器官都涉及再循环，并且假定子宫与母体血浆以及胎儿器官与胎儿血浆之间存在平衡。使用医学内照射剂量测定法，根据胎儿和胎盘中的137Cs估算胎儿和胎盘所吸收的剂量。在妊娠第一阶段，胚胎/胎儿所受剂量为1.3×10(-5) Gy Bq(-1)，到最后阶段降至8.3×10(-6) Gy Bq(-1)。随着孕期推进，胎盘所受剂量也降低。在确定胎儿剂量估算值时，未考虑母体器官中的137Cs。
