Department of Oncology-Pathology, Medical Radiation Physics, Karolinska Institutet and Stockholm University, PO Box 260, SE-171 76 Stockholm, Sweden.
Phys Med Biol. 2011 Apr 7;56(7):1985-2003. doi: 10.1088/0031-9155/56/7/005. Epub 2011 Mar 2.
A Monte Carlo code for the event-by-event simulation of electron transport in liquid water is presented. The code, written in C++, can accommodate different interaction models. Currently it implements cross sections for ionizing collisions calculated with the model developed by Dingfelder et al (1998 Radiat. Phys. Chem. 53 1-18, 2008 Radiat. Res. 169 584-94) and cross sections for elastic scattering computed within the static-exchange approximation (Salvat et al 2005 Comput. Phys. Commun. 165 157-90). The latter cross sections coincide with those recommended in ICRU Report 77 (2007). Other included interaction mechanisms are excitation by electron impact and dissociative attachment. The main characteristics of the code are summarized. Various track penetration parameters, including the detour factor, are defined as useful tools to quantify the geometrical extent of electron tracks in liquid water. Results obtained with the present microdosimetry code are given in the form of probability density functions for initial electron kinetic energies ranging from 0.1 to 10 keV. The sensitivity of the simulated distributions to the choice of alternative physics models has been briefly explored. The discrepancies with equivalent simulations reported by Wilson et al (2004 Radiat. Res. 161 591-6) stem from the adopted cross sections for elastic scattering, which determine largely the spatial evolution of low-energy electron tracks.
本文介绍了一种用于液体水中电子输运逐事件模拟的蒙特卡罗代码。该代码用 C++编写，可以适应不同的相互作用模型。目前，它实现了由 Dingfelder 等人开发的用于电离碰撞的截面模型（1998 年 Radiat. Phys. Chem. 53 1-18，2008 年 Radiat. Res. 169 584-94）和静态交换近似（Salvat 等人，2005 年 Comput. Phys. Commun. 165 157-90）计算的弹性散射截面。后者的截面与 ICRU 报告 77（2007）中推荐的截面一致。其他包括的相互作用机制是电子碰撞激发和离解吸附。总结了代码的主要特点。定义了各种穿透参数，包括迂回因子，作为量化电子在液体水中的轨迹几何范围的有用工具。给出了初始电子动能范围从 0.1 到 10 keV 的概率密度函数形式的本微剂量学代码的结果。简要探讨了替代物理模型选择对模拟分布的敏感性。与 Wilson 等人（2004 年 Radiat. Res. 161 591-6）报告的等效模拟的差异源于所采用的弹性散射截面，这些截面在很大程度上决定了低能电子轨迹的空间演化。
