高能医用电子束输出因子的剂量学特性  

Dosimetry characters of output factors of medical high-energy electrons

作　　者：张颖[1] 陶建民[1] 胡杰[1] 张莹[1] 

机构地区：[1]同济大学附属第十人民医院放射治疗科,上海200072

出　　处：《现代医学》2010年第5期458-461,共4页Modern Medical Journal

基　　金：上海铁路局科技研究开发项目(2002Y04)

摘　　要：目的:研究直线加速器高能电子束输出因子的剂量学特性,为临床准确使用输出因子提供依据。方法:测量SIEMENS MD7745和GE Saturne41直线加速器9 MeV和12 MeV高能电子束的不同射野最大剂量点剂量率,计算输出因子,然后分析数据。结果:准直器铅门大小、限光筒大小和实际照射野形状对高能电子束输出因子影响很大,必须按一定的使用规范才能保证剂量计算精度达到世界卫生组织WHO规定的要求。结论:对SIEMENS MD7745型直线加速器的电子束射野成形模式,限光筒大小应尽量接近临床实际射野大小;当射野边长大于电子束射程时,使用限光筒开野的输出因子进行剂量学的计算,而边长小于电子束射程的射野,必须按临床射野情况有针对性地实际测量输出因子的大小进行剂量学的计算。对GE Saturne41型直线加速器的电子束成形模式,必须测量输出因子射野两维表并应用于临床处方剂量学的计算。Objective： To study the dosimetry characters of the output factors of high-energy electrons of linear accelerators and to provide the method for accurate clinical usage.Methods： First,we measured the dose rate for different fields at dmax depth for 9 MeV and 12 MeV high-energy electrons by SIEMENS MD7745 and GE Saturne41 medical linear accelerators,then we calculated the output factors and analyzed the datas.Results： The output factors was strongly related to collimator sizes and applicator sizes and block fields.In order to attain the rules from WHO for Quality Assurance in radiotherapy,we must use these factors under special regulation.Conclusion： For SIEMENS MD7745 linear accelerator the applicator size must be close to the lead block field in clinical usage,on this basis we can use the output factors of open field for standard applicators to replace the lead block field when the field size is larger than Rp,but we must measure the output factors for those fields which sizes are less than Rp.For GE Saturne41 linear accelerator,we must measure and make the two dimensional chart of output factor-field for clinical usage.

关 键 词：输出因子 高能电子束 直线加速器 放射治疗 剂量测量 

分 类 号：R814.2[医药卫生—影像医学与核医学]