15 MV医用直线加速器X射线束的MCNP模拟  

MCNP simulation of X-ray beam for a 15 MV medical linear accelerator

作　　者：邓磊 周宁[1] 瞿述根 王哲 王健 陈以水 涂彧 刘永泉[1] DENG Lei;ZHOU Ning;QU Shugen;WANG Zhe;WANG Jian;CHEN Yishui;TU Yu;LIU Yongquan(Institute of Occupational Medicine of Jiangxi,Nanchang 330006,China;State Key Laboratory of Radiation Medicine and Protection(Soochow University),Suzhou 215123,China;School of Public Health and Management,Wenzhou Medical University,Wenzhou 325035,China)

机构地区：[1]江西省职业病防治研究院,南昌330006 [2]放射医学与辐射防护国家重点实验室(苏州大学),苏州215123 [3]温州医科大学公共卫生与管理学院,温州325035

出　　处：《核技术》2021年第11期25-30,共6页Nuclear Techniques

基　　金：放射医学与辐射防护国家重点实验室项目(No.GZK1202019)资助。

摘　　要：高能医用直线加速器在放射治疗中的应用越来越广泛,其辐射源项及屏蔽防护研究一直是人们关注的重点。应用MCNP(Monte Carlo N-Particle Transport Code)软件对Clinac 23EX型医用直线加速器产生的15 MV X射线束进行模拟。依据厂家提供的机头内部件的材料组成和几何尺寸,构建X射线模式的加速器机头精细模型,计算了不同照射野下X射线束在水模体中的百分深度剂量(Percentage Depth Dose,PDD)曲线和剖面相对剂量(Profile)曲线。模拟计算结果与三维水箱的实测结果基本吻合,表明本研究建立的模型准确可靠,可应用于后续医用直线加速器各类辐射源项的研究。另外,通过分析机头不同组件对X射线束能谱及穿透能力的影响程度,可为优化屏蔽设计和放疗计划提供参考。[Background]The application of high-energy medical electron accelerators in the radiotherapy becomes more and more widespread.Study of the radiation source and shielding of high-energy medical electron accelerators has been the focus of attention.[Purpose]This study aims to simulate 15 MV X-ray beam of Clinac 23EX medical linear accelerator by using Monte Carlo method.[Methods]First of all,a fine geometric model of the accelerator head in X-ray mode was constructed according to the material composition and geometric dimensions of the internal parts of the head provided by the manufacturer.Then the Monte Carlo N-Particle Transport Code(MCNP)software was applied to the calculation of the percentage depth dose(PDD)curves and profile curves of the X-ray beam under different irradiation fields.Comparisons of those results with that of measured results at the same conditions in the three-dimensional(3D)water model were performed.In addition,the effects of different components on the X-ray energy spectrum and penetration ability were analyzed.[Results]The simulation results of the PDD curves and profile curves are in good agreement with the measured results of 3D water tank.The relative deviation of PDD curves is in the range of 0.62%to 1.34%,and the relative deviations of profile curves are between 0.35%and 2.76%in high dose area and 0.48%to 5.86%in low dose area,respectively.[Conclusions]It is confirmed that the detailed model of the accelerator head established in this study is accurate and reliable,hence appliable to the subsequent analysis of various source items.The effects of different components of accelerator on the X-ray energy spectrum and penetration ability provide references for optimizing shielding design and radiotherapy plan.

关 键 词：医用电子加速器 X射线束 百分深度剂量 蒙特卡罗 

分 类 号：TL99[核科学技术—核技术及应用]