西门子加速器射束特点的Geant4模拟研究  

Simulation study on Siemens accelerator beam characteristics with Geant4 code

作　　者：孔栋[1] 苗利[1] 赵飞[1] 陈勇[1] 倪婕[1] 顾思毅 孙亮[1] 

机构地区：[1]苏州大学医学部放射医学与防护学院,苏州215123

出　　处：《辐射研究与辐射工艺学报》2013年第5期58-64,共7页Journal of Radiation Research and Radiation Processing

摘　　要：利用Geant4程序包编程构建SIEMENS直线加速器机头结构,模拟产生6MV-X射线的电子打靶及后续粒子输运过程,通过与测量数据对比,在保证模型构建合理的基础上,获取常用射野平面粒子出射信息并分析所得相空间文件,得到光子和电子的平均能量、能谱分布、粒子注量分布、能量注量分布及角分布等信息。结果表明:出射光子平均能量要高于电子;光子和电子能谱呈连续分布;出射电子粒子注量与光子相差两个数量级以上;射野内光子的粒子注量和能量注量分布较均匀,电子则波动很大;射野外光子粒子注量和能量注量均迅速下降,电子的变化趋势不太明显;出射光子角分布主要集中在与中心轴成10°范围内,电子角分布范围则较大。The Geant4 code was used to model components of the head of Siemens medical linear accelerator with the field commonly used. Then we simulated the process of electron beams, which could produce 6 MV X-rays, bombarding a gold target. By comparison with the measured data, we ensured that the model was built correctly. Then we obtained the information of all the particles to the field plane, and wrote it to a phase space file. The kinds of particles and their average energy, energy spectrum distributions, particle fluence distributions, energy fluence distributions, and angular distributions were presented by processing the file with the procedure written by myself. The results show that the average energy of photon is higher than that of electron and positron; energy spectra of photon and electron show continuous distributions; electronic particle fluence is two orders of magnitude less than that of photons; particle fluence and energy fluence of photons are evenly distributed in the field and decrease rapidly out of the field, while the electronic＇s fluctuate considerably in the field and smoothly out of the field. Angular distribution of photon is mainly concentrated within the range of 10° off the central axis, while the electronic＇s are in a relatively larger range.

关 键 词：加速器 蒙特卡罗 百分深度剂量 离轴比 能谱 注量 角分布 

分 类 号：TL53[核科学技术—核技术及应用]