Guo Bingqi, Xu X George, Shi Chengyu
Radiation Oncology, University of Texas Health Science Center at San Antonio, Ste G240, San Antonio, TX 78229, USA.
Radiat Prot Dosimetry. 2010 Jan;138(1):20-8. doi: 10.1093/rpd/ncp182. Epub 2009 Sep 18.
The specific absorbed fraction (Phi), defined by the Medical Internal Radiation Dose Committee, is generally applied to evaluate the average absorbed dose in a target organ as a result of radioactive materials deposited in a source organ. This paper reports a new set of Phi values for internal electron emitters ranging from 10 keV to 4 MeV from various internal organs of the mother to the fetus based on three newly developed pregnant female tomographic models, called RPI-P3, RPI-P6 and RPI-P9. The results show a linear log relationship between Phi values and electron energy. The linear log coefficients have been derived and reported. The relationship between Phi values and mean distances between source organs and the fetus were also determined to allow for individual dosimetry. Since the RPI-P models have finer details of human anatomy and more realistic organ volumes and geometries, which follow the latest ICRP reference values, the newly derived Phi values could be used as reference values in determination of the dose to the fetus from internal electron emitters.
由医学内照射剂量委员会定义的比吸收分数（Phi），通常用于评估源器官中沉积的放射性物质在靶器官中产生的平均吸收剂量。本文基于新开发的三种孕妇断层模型，即RPI-P3、RPI-P6和RPI-P9，报告了从母亲各内部器官到胎儿的10 keV至4 MeV范围内的内电子发射体的一组新的Phi值。结果表明，Phi值与电子能量之间存在线性对数关系。已推导并报告了线性对数系数。还确定了Phi值与源器官和胎儿之间平均距离的关系，以进行个体剂量测定。由于RPI-P模型具有更精细的人体解剖细节、更符合实际的器官体积和几何形状，且遵循国际辐射防护委员会（ICRP）的最新参考值，因此新推导的Phi值可作为确定内电子发射体对胎儿剂量的参考值。
