基于蒙特卡罗方法对光子束剂量沉积核的研究  

Research of photon beam dose deposition kernel based on Monte Carlo method

作　　者：苗利[1] 刘胜堂[1] 孙彦泽[1] 孔栋[1] 顾熹豪[1] 李新民[1] 

机构地区：[1]苏州大学医学部放射医学与防护学院,江苏省放射医学与防护重点实验室,苏州215123

出　　处：《核技术》2013年第1期43-47,共5页Nuclear Techniques

基　　金：江苏高校优势学科建设工程资助项目(PAPD)

摘　　要：用蒙特卡罗的程序BEAMnrc模拟西门子加速器6 MV光子束,由BEAMdp子程序分析得到不同射野的能谱分布和平均能量,并建立相应模拟源(能谱源与单能源),由DOSXYZnrc子程序使用模拟源笔形束,在标准水模体中计算最大剂量深度处的剂量沉积核,以比较不同源对剂量沉积的影响。结果表明,不同射野下获得的能谱源对剂量沉积的差异较小,最大百分剂量差1.47%;使用平均能量的单能源剂量差别较大,最大达6.28%。而对于利用同一射野下能谱源和单能源计算的剂量核进行比较,最大百分剂量差在9%以上,甚至达到13.2%。由此可见,剂量沉积核具有光子能量依赖性,由于加速器产生的光子束是具有能谱分布的,只利用某一单能源来进行剂量计算会造成较大的误差,使用能谱源计算剂量沉积核会更为准确。Using Monte Carlo program BEAMnrc to simulate Siemens accelerator 6 MV photon beam, using BEAMdp program to analyse the energy spectrum distribution and mean energy from phase space data of different field sizes, then building beam source, energy spectrum and mono-energy source, to use DOSXYZnrc program to calculate the dose deposition kernels at dmax in standard water phantom with different beam sources and make comparison with different dose deposition kernels. The results show that the dose difference using energy spectrum source is small, the maximum percentage dose discrepancy is 1.47%, but it is large using mono-energy source, which is 6.28%. The maximum dose difference for the kernels derived from energy spectrum source and mono-energy source of the same field is larger than 9%, up to 13.2%. Thus, dose deposition has dependence on photon energy, it can lead to larger errors only using mono-energy source because of the beam spectrum distribution of accelerator. A good method to calculate dose more accurately is to use deposition kernel of energy spectrum source.

关 键 词：放射治疗 蒙特卡罗 笔形束 剂量沉积核 直线加速器 

分 类 号：R811.1[医药卫生—放射医学] R815[医药卫生—临床医学]