应用蒙特卡罗方法研究医用加速器光子能谱分布  

Research Photon Energy Spectrum of Medical Linear Accelerator by Monte Carlo Method

作　　者：徐云 赵宇[1] 李自康 吴骏翔 XU Yun;ZHAO Yu;LI Zikang;WU Junxiang(Oncology Department,West China Hospital of Sichuan University Ya'an People's Hospital,Ya'an,625000;Radiotherapy Center,Sichuan Cancer Hospital,Chengdu,610041)

机构地区：[1]四川大学华西医院雅安医院肿瘤科,雅安市625000 [2]四川省肿瘤医院放疗中心,成都市610041

出　　处：《中国医疗器械杂志》2024年第2期156-159,共4页Chinese Journal of Medical Instrumentation

摘　　要：目的研究医用直线加速器在等中心平面的光子能谱分布和次级准直器对光子能谱的影响。方法使用BEAMnrc程序模拟5 cm×5 cm、10 cm×10 cm、15 cm×15 cm和20 cm×20 cm射野下,能量为6 MeV电子和光子在加速器治疗头中的输运行为,在等中心平面处设置相空间记录文件,以记录经过此平面的粒子信息。然后利用BEAMdp程序对相空间文件进行分析,从而获得在等中心平面的光子能谱分布及次级准直器对光子能谱的影响。结果通过分析标称能量为6 MV的医用直线加速器的光子能谱,发现次级准直器对光子能谱影响很小;不同射野具有不同的光子能谱分布;同一射野不同中心区域的光子能谱具有相同的归一化分布。结论在放射治疗的剂量计算中,应仔细考虑光子能谱的影响。Objective The distribution of the photon energy spectrum in isocenter plane of the medical linear accelerator and the influence of secondary collimator on the photon energy spectrum are studied.Methods Use the BEAMnrc program to simulate the transmission of the 6 MeV electrons and photons in 5 cm×5 cm,10 cm×10 cm,15 cm×15 cm and 20 cm×20 cm fields in treatment head of the medical linear accelerator,where a phase space file was set up at the isocenter plane to record the particle information passing through this plane.The BEAMdp program is used to analyze the phase space file,in order to obtain the distribution of the photon energy spectrum in isocenter plane and the influence of secondary collimator on the photon energy spectrum.Results By analyzing the photon energy spectrum of a medical linear accelerator with a nominal energy of 6 MV,it is found that the secondary collimator has little effect on the photon energy spectrum;different fields have different photon energy spectrum distributions;the photon energy spectrum in different central regions of the same field have the same normalized distribution.Conclusion In the dose calculation of radiation therapy,the influence of photon energy spectrum should be carefully considered.

关 键 词：蒙特卡罗方法 光子 医用直线加速器 能谱 

分 类 号：R815.6[医药卫生—放射医学] TH77[医药卫生—临床医学]