基于EGSnrc仿真的二维电离室剂量探测器的室壁厚度确定方法

摘要

The wall-thickness is an important design parameter for two-dimensional ionization chamber dose detector. Under the given geometric parameters of the cavity unit of two-dimensional ionization chamber dose detector, the simulation model was built by using Monte Carlo method. The wall-thickness was calculated with the simulation model using EGSnrc, and the reference numerical value was given. The result shows that when the cavity is a cylinder with diameter of 4. 5mm and height of 5mm, under radiation of 1. 25MeV, the front wall-thickness of ionization chamber should be more than 4. 4mm and the side wall-thickness should be 1. 5mm in order to meet the demand of accuracy of 1％. Under the radiation with energy of 1. 25-4 MeV, the side wallthickness should be more than 5mm in order to meet the demand of accuracy of 1％. The research result can be used as the design basis for the detector.%室壁厚度是二维电离室剂量探测器的重要设计参数.在二维电离室剂量探测器的单元空腔几何参数确定的情况下,利用蒙特卡罗仿真方法建立了探测器室壁仿真计算的简化模型,并利用EGSnrc程序对模型进行了仿真计算,给出了室壁厚度的参考数值.结果 表明,当空腔为直径4.5mm、高5mm的圆柱形时,在能量为1.25MeV射线下,为达到1％的测量精度,电离室前壁厚度需达到4.4mm,侧壁厚度需达到1.5mm;在1.25～4MeV射线能量范围内使用时,为达到1％的测量精度,侧壁厚度需达到5mm.本文研究结果可作为该种探测器的设计依据.