碳离子放射治疗计划中MKM和LEM模型的处方剂量转换研究  

Carbon ion radiotherapy planning:a study of prescription dose conversion between microdosimetric kinetic model and local effect model

作　　者：左子杰 刘志强 张庆华 韩旭 杜天奇 罗宏涛 孙世龙 张宇[2] 张秋宁 王小虎[1,5] Zuo Zijie;Liu Zhiqiang;Zhang Qinghua;Han Xu;Du Tianqi;Luo Hongtao;Sun Shilong;Zhang Yu;Zhang Qiuning;Wang Xiaohu(Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China;School of Nuclear Science and Technology,Lanzhou University,Lanzhou 730000,China;Lanzhou Ion Therapy Co.,Ltd.,Lanzhou 730000,China;The First School of Clinical Medicine,Lanzhou University,Lanzhou 730000,China;University of Chinese Academy of Sciences,Beijing 100049,China;Lanzhou Heavy Ion Center,Lanzhou Branch of Gansu Wuwei Tumor Hospital,Lanzhou 730000,China)

机构地区：[1]中国科学院近代物理研究所,兰州730000 [2]兰州大学核科学与技术学院,兰州730000 [3]兰州泰基离子技术有限公司,兰州730000 [4]兰州大学第一临床医学院,兰州730000 [5]中国科学院大学,北京100049 [6]甘肃省武威肿瘤医院兰州院区兰州重离子中心,兰州730000

出　　处：《中华放射肿瘤学杂志》2025年第2期151-159,共9页Chinese Journal of Radiation Oncology

基　　金：国家重点研发计划项目(2022YFC2401500);兰州市科技计划项目(2023-1-9);国家自然科学基金青年学生基础研究项目(123B2090);中央引导地方科技发展资金项目(24ZYQA029)。

摘　　要：目的在碳离子水模体计划中,建立微剂量动力学模型(MKM)和局部效应模型(LEM)处方剂量的转换因子计算系统和危及器官转换因子曲线,并在临床患者计划中验证。方法以均匀水模体作为研究对象,根据RayStation-MKM计划的物理剂量重新计算LEM的相对生物学效应加权剂量(RWD),并以LEM和MKM计划中靶区中位剂量的比值作为转换因子。分别研究靶区单次处方剂量、扩展布拉格峰(SOBP)宽度、深度、形状和照射方式对转换因子的影响,并建立转换因子计算系统。此外,采用水模体和临床患者病例验证转换因子计算系统的准确性,并根据临床患者治疗计划计算建立危及器官转换因子曲线。结果转换因子的主要影响因素为单次处方剂量、靶区SOBP宽度和深度,并随SOBP宽度和靶区深度的增加而增加,随单次处方剂量的增加而减小。在单野照射下,根据以上3个参数建立转换因子计算系统,9例患者计划计算与转换因子计算系统计算的结果平均差异为0.340%±0.203%,危及器官转换因子曲线的平均差异为2.650%±2.399%。结论本研究建立的MKM和LEM碳离子放射治疗处方剂量转换因子计算系统和危及器官转换因子曲线,其准确性满足在临床患者治疗计划中的使用要求。Objective In carbon ion treatment planning of water phantom,establish a conversion factor calculation system and conversion factor curves for organs at risk(OAR)for microdosimetric kinetic models(MKM)and local effect models(LEM),and validate them in clinical patient planning.Methods Using a uniform spherical water phantom as the research object,relative biological effectiveness-weighted doses(RWD)for the LEM were re-calculated based on the physical dose of RayStation-MKM.The median dose within the planning target volume(PTV)of LEM and MKM was regarded as the conversion factor.The impacts of single-fraction target prescription dose,spread-out Bragg peak(SOBP)width and depth,shape,and irradiation mode on the conversion factor were assessed,and a conversion factor calculation system was established.Additionally,the accuracy of the conversion factor calculation system was validated using both water phantoms and clinical patient cases.The conversion factor curves for OAR were computed based on clinical patient treatment plans.Results The primary influencing factors for the conversion factors were the single-fraction prescription dose,target SOBP width and depth.The conversion factors were increased with the increase of SOBP width and target depth,whereas decreased with the increase of the single-fraction prescription dose.Under single-field irradiation,a conversion factor calculation system was established based on above 3 parameters.For the plans of 9 patients,the average difference between the calculated results and the conversion factor calculation system was 0.340%±0.203%,and the average difference in the conversion curves for OAR was 2.650%±2.399%.Conclusion A dose conversion factor calculation system and conversion factor curves for OAR for carbon ion radiotherapy are established for MKM and LEM,and their accuracy meets the requirements for use in clinical patient treatment plans.

关 键 词：放射疗法 碳离子 微剂量动力学模型 局部效应模型 前列腺肿瘤 脊索瘤 

分 类 号：TP3[自动化与计算机技术—计算机科学与技术]