^(60)Co远程治疗机剂量场分布的Monte Carlo计算

Monte Carlo calculations of dose distributions for a ^(60)Co long-distance treatment machine

基于60Co放射源的远程治疗机是常用的放疗设备。对治疗机的靶区做精确的剂量计算有助于确保放疗质量。传统的半经验解析方法在计算上适用范围小,几何模型稍显复杂之后就难以得到理想的结果。本文使用Monte Carlo方法,借助于EG S4软件包计算了不同射野下60Co远程治疗机在水膜体中的三维剂量场分布。为了提高抽样效率,对源粒子的运动方向采用了解析方法确定。将得到的计算结果与用RTS-200S自动扫描水箱测量的离轴剂量和中心轴深度剂量比较,二者符合得很好。

60Co radiological treatment machines are commonly used in hospitals. Accurate analyses for the treatment target volume will help insure radiation therapy quality.Traditional empirical methods are of limited use in complex geometries.Here,the Monte Carlo method was used to calculated the 60Co γ ray dose distribution in a water phantom using the EGS software package.The sampling efficiency is improved by use of an analytical method to confirm the direction of the incident particles.The results show that the off-axis and the depth dose distribution calculated by the Monte Carlo method agree very well with measurements using an RTS-200S.