Chen J
Radiation Protection Bureau, Health Canada, 775 Brookfield Road, Ottawa K1A 1C1, Canada.
Radiat Prot Dosimetry. 2007;126(1-4):568-71. doi: 10.1093/rpd/ncm115. Epub 2007 May 24.
The Monte Carlo code MCNPX has been used to determine mean absorbed doses to the embryo and foetus when the mother is exposed to neutron fields. There are situations, such as on-board aircraft, where high-energy neutrons are often peaked in top down (TOP) direction. In addition to previous publications for standard irradiation geometries, this study provides absorbed dose conversion coefficients for the embryo of 8 weeks and the foetus of 3, 6 or 9 months at TOP irradiation geometry. The conversion coefficients are compared with the coefficients in isotropic irradiation (ISO). With increasing neutron energies, the conversion coefficients in TOP irradiation become dominant. A set of conversion coefficients is constructed from the higher value in either ISO or TOP irradiation at a given neutron energy. In cases where the irradiation geometry is not adequately known, this set of conversion coefficients can be used in a conservative dose assessment for embryo and foetus in neutron fields.
蒙特卡罗代码MCNPX已被用于确定母亲暴露于中子场时胚胎和胎儿的平均吸收剂量。在某些情况下，比如在飞机上，高能中子往往在自上而下（TOP）方向上达到峰值。除了之前关于标准辐照几何形状的出版物外，本研究还提供了在TOP辐照几何形状下8周龄胚胎以及3、6或9月龄胎儿的吸收剂量转换系数。将这些转换系数与各向同性辐照（ISO）下的系数进行了比较。随着中子能量的增加，TOP辐照下的转换系数占主导地位。在给定中子能量下，从ISO或TOP辐照中的较高值构建了一组转换系数。在辐照几何形状不太清楚的情况下，这组转换系数可用于中子场中胚胎和胎儿的保守剂量评估。
