摘要
目的:分析一种利用高低两档能量光子拟合任意中间能量光子的方法,并与现有方法进行对比。方法:百分深度剂量曲线(PDD)和离轴剂量分布曲线(OCR)是影响光子射束数据模型计算精度的两个重要特征参数。使用Varian Truebeam直线加速器模型中金标准射束数据6和15 MV射束的PDD和OCR数据,采用最小二乘拟合方法拟合中间能量10 MV射束,与金标准数据10 MV射束数据比较分析,并与其他拟合方法进行对比,证明该方法的可行性和有效性。基于三维仿真水模体数据和不同肿瘤部位的实际病例数据实验,进一步验证合成能量方法的准确性。结果:相比只考虑PDD数据的能量拟合方法,本研究方法得到的合成能量10 MV与金标准数据10 MV光子束相比,各尺寸射野下PDD的均方根误差有所增加,但均小于1%,而OCR的均方根误差明显减小(特别是20 cm以上的射野),均小于0.5%。三维仿真水模体数据和实际患者数据测试例实验结果优于只考虑PDD数据的能量拟合方法。结论:利用PDD和OCR数据合成光子能量方法的效果较仅使用PDD数据的方法更好,合成能量光子与实际10 MV光子之间PDD和OCR差异较小,基于三维仿真水模体和实际病例数据的不同放疗技术计划三维剂量分布的一致性很高,拟合能量光子可代替实际能量光子用于临床治疗。
Objective To propose an energy synthesis method that can fit photons with any known intermediate energies through high-and low-energy photons and compare it with the existing method.Methods Percentage depth dose(PDD)and off-center ratio(OCR)are two important characteristics that affect the calculation accuracy of the beam model.The study adopted the PDD and OCR of the gold standard data(6 and 15 MV beams)of Varian TrueBeam accelerator,and used the least squares fitting method to fit the intermediate energy(Esyn-10 MV).The Esyn-10 MV was compared with the gold standard data(TB-10 MV),and the proposed method was compared with other fitting method for validating the feasibility and validity of the method.The accuracy of the energy synthesis method was further verified by experiments with 3D water phantom and the actual cases of different tumor sites.Results Compared with the energy synthesis method that only considers PDD,the proposed method obtained the Esyn-10MV with increased PDD root mean square error under each size of the field and reduced OCR root mean square error(especially for fields above 20 cm),and the root mean square errors of PDD and OCR were all less than 1.0%and 0.5%.The experimental results of the proposed method on 3D water phantom and the actual cases were also better than those of the energy synthesis method that only considers PDD.Conclusion The energy synthesis method that considers both PDD and OCR is superior to that only considering PDD,and the differences in PDD and OCR between Esyn-10 MV photons and TB-10 MV photons are trivial.The consistency of 3D dose distribution in different radiotherapy plans for 3D water phantom and the actual cases is high.Therefore,the synthetic energy photons can replace actual energy photons for clinical treatment.
作者
张喜乐
周付根
刘博
吴秋文
ZHANG Xile;ZHOU Fugen;LIU Bo;WU Qiuwen(Image Processing Center,Beihang University,Beijing 100191,China;Department of Radiation Oncology,Peking University Third Hospital,Beijing 100191,China;Department of Radiation Oncology,Duke University Medical Center,Durham 3295,USA)
出处
《中国医学物理学杂志》
CSCD
2023年第7期793-800,共8页
Chinese Journal of Medical Physics
基金
国家重点研发计划(2019YFB1311300,2019YFB1311301)。
关键词
放射治疗
光子能量合成
百分深度剂量
离轴剂量
radiotherapy
photon energy synthesis
percentage depth dose
off-center ratio
作者简介
张喜乐,博士,研究方向:放射治疗中光子能量优化方法、影像引导的调强放射治疗技术和治疗计划快速优化等,E-mail:xile.zhang@hsc.pku.edu.cn;通信作者:周付根,博士,教授,博士生导师,研究方向:多模图像配准与融合、生物医学成像、图像处理与识别,E-mail:zhfugen@buaa.edu.cn。
