基于蒙特卡罗方法的医用电子直线加速器最优剂量参数及输出剂量测量质量控制研究  

Study on optimal dose parameters of medical electron linear accelerator and the quality control for measurement of its output dose on the basis of Monte Carlo method

作　　者：杜涌泉 杜建华 代伟 DU Yong-quan;DU Jian-hua;DAI Wei(Radiotherapy Center, The People's Hospital Guang'an City, Guang'an 638000, China)

机构地区：[1]广安市人民医院放疗中心,四川广安638000 [2]广安市人民医院设备科,四川广安638000

出　　处：《中国医学装备》2019年第5期22-25,共4页China Medical Equipment

摘　　要：目的:分析基于蒙特卡罗方法研究医用电子直线加速器的最优剂量参数及其输出剂量测量的质量控制。方法:采用蒙特卡罗方法模拟Varian 600C医用电子直线加速器在10 cm×10 cm射野下6 MV能量的剂量分布,计算10 cm深度处离轴比与水模体百分深度剂量曲线;通过剂量监测仪器读数刻度,对源轴距(SAD)、源皮距(SSD)照射等中心给角照射处方剂量计算,寻找最优剂量参数简化方法,进行数据处理分析。结果:当电子直线加速器径向强度分布为0～0.19 cm变化时,测量与模拟的主剂量区内离轴剂量差异最小;对平均角展宽进行调整,有助于提高测量与模拟的离轴剂量符合度。当电子直线加速器径向强度与平均能量分别在0.1～0.4 cm及5.5～6.4 MeV时,百分深度剂量无较大变化。结论:使用蒙特卡罗方法模拟医用电子直线加速器剂量输出,可在照射野内找到最优的径向轻度分布与电子束能量参数组合;同时可指导加速器输出剂量测量建立完整质量控制体系。Objective: To analyze the optimal dose parameters of medical electron linear accelerator and the quality control for measurement of its output dose on the basis of Monte Carlo method. Methods: Monte Carlo method was used to simulate the dose distribution of the Varian 600C medical electron linear accelerator of 6MV energy beam under the 10 cm ×10 cm radiation field. The dose curves of the off-axis ratio at the depth of 10 cm and the percentage depth of water phantom were calculated. Through the scale of dosimeter readout, the prescribed dose of central angle irradiation such as SAD, SSD and others were calculated, and then to search the simplified method of the optimal dosimetric parameters so as to implement data processing and analysis for them. Results: When the radial intensity distribution of electron linear accelerator was changed from 0 to 0.19 cm, the difference of the off-axis dose in the main dose area between measured value and simulated value was the smallest. The adjustment of average angular widening helped to increase the conformity of off-axis dose of the measured value and simulated value. When the radial strength and average energy of the electron linear accelerator were 0.1-0.4 cm and 5.5-6.4 MeV, respectively, the percentage depth dose did not be changed much. Conclusion: Through use Monte Carlo method to simulate the output of medical electron linear accelerator can find the optimal combination of radial light distribution and electron beam energy parameters in the irradiation field. At the same time, it can guide the measurement of output dose of accelerator to establish a complete quality control system.

关 键 词：质量控制 输出剂量测量 电子直线加速器 蒙特卡罗方法 

分 类 号：R197.39[医药卫生—卫生事业管理]