食管癌容积旋转调强与动态调强放疗计划的等效生物剂量分布比较  

Comparison of equivalent dose distribution between volumetric modulated arc therapy and dynamic-MLC IMRT for esophageal cancer

作　　者：陈翠[1] 张广顺[1] 卢丽霞[1] 邓小武[1] CHEN Cui;ZHANG Guang-shun;LU Li-xia;DENG Xiao-wu(State Key Laboratory of Oncology in Southern China,Department of Radiation Oncology,Sun Yat-sen University Cancer Center,Guangzhou 510060,P.R.China)

机构地区：[1]华南肿瘤学国家重点实验室中山大学肿瘤防治中心放射治疗科,广东广州510060

出　　处：《中华肿瘤防治杂志》2018年第15期1075-1080,共6页Chinese Journal of Cancer Prevention and Treatment

基　　金：中山大学肿瘤防治中心308临床研究基金(2014-FXY-101-放疗科;308-2015-011)

摘　　要：目的食管癌使用不同调强放射治疗技术会得到不同物理剂量和等效生物剂量分布。使用等效生物剂量评估可以更好预测放疗效果。本研究比较使用容积旋转调强(volumetric modulated arc therapy,VMAT)和5野、7野、9野动态调强(5F-,7F-,9F-dynamic MLC-IMRT)4种技术在食管癌放疗计划中的等效生物剂量(equivalent dose in 2Gy/f,EQD2)与物理剂量的分布差别,为临床选择最佳放疗技术提供依据。方法选择中山大学肿瘤防治中心2015-03-05-2015-06-27收治的20例食管癌患者,分别使用5F-、7F-、9F-dMLC-IMRT和VMAT技术各设计4套计划,所有计划使用相同的临床目标和剂量限制条件,肿瘤靶区的处方剂量均为60Gy/28f。根据各器官的α/β值和线性二次(linearquadratic,L-Q)模型,采用自编软件对治疗计划所有体素点物理剂量进行转换,得到治疗计划各体素点的EQD2剂量、以及靶区和危及器官的生物等效剂量体积(DVHEQD2)数据。比较不同调强放疗技术物理剂量和生物等效剂量体积参数差异,包括靶区相关剂量参数、适形指数(conformal index,CI)、均匀性指数(homogeneity index,HI)和脊髓、肺、心脏等危及器官体积剂量参数,并根据EQD2剂量分布综合结果选择最佳放疗技术。结果肿瘤区和预防照射区剂量体积参数中生物等效剂量(DEQD2)与物理剂量(DPhys)差别<3.5%;各危及器官的剂量参数中,DEQD2低于DPhys,均>10%。使用DEQD2对4种调强放疗技术进行比较,肿瘤区的处方剂量包绕体积均>98%,差别没有统计学意义(P>0.05),VMAT的靶区适形性(适形指数CI=0.554)高于动态调强技术技术(适形指数CI9F、CI7F和CI5F分别为0.535、0.473和0.408),P<0.001;危及器官的剂量参数中,脊髓最大量、心脏的平均剂量、肺的平均剂量和体积剂量VEQD2-20Gy和VEQD2-30Gy在不同调强技术之间差异<3%。VMAT技术肺的VEQD2-5Gy比5F-IMRT高4.51%,低于使用物理剂量评估时的7.58%。结论综合比较4组不同�OBJECTIVE Different physical dose and equivalent dose in 2 Gy/f distribution can be obtained by differ- ent intensity modulated radiation therapy for esophageal cancer. Using equivalent dose in 2 Gy/f assessment can better predict the effect of radiotherapy. The aim of this study was to compare the difference of physical dose and equivalent dose in 2 Gy/f between volumetric modulated arc therapy and 5 fields-,7 fields- , and 9 fields- dynamie-MLC IMRT for esopha- geal cancer,which provided the basis for clinical choice of optimal radiotherapy techniques. METHODS From March 5th to June 27th,2015,20 patients with esophageal cancer were given VMAT and 5F-, 7F-, 9F-dMLCqMRT plans respective- ly,using the same prescribed aim of 60 Gy/28 f and Dose limiting condition. According to a/13 value of each organ and line- ar-quadratic model,convert physical dose of each voxel to EQD2 by self-compiled software and compare the difference of physical dose and EQDz between VMAT and 5F-, 7F-, 9F-dMLC IMRT plans. Dosimetric comparisons including the target area,eonformal index（CI） and homogeneity index（HI） and organ-at-risk such as spinal cord,lung and heart which were analyzed to select the optimal radiotherapy techniques. RESULT There was no significant difference between physi- cal dose and EQDz in the tumor area and the irradiation zone of prevention, which was less than 3.5 %. DEQDZ was lower than Dphyn OAR,which was more than 10%, Comparing the distribution of EQD2 of VMAT and dMLC, there was no difference in target coverage which was higher than 98% and maximum of spinal cord,mean dose of heart, VEQD2-20 Gyand VEQD2--30 ayof lung which was lower than 3% （P〉0. 05）. The CI of VMAT was 0. 554 which was higher than other tech- niques（the CI of 9F, 7F, and 5F dMLC-IMRT was 0. 535,0. 473 and 0. 408, respectively, P〈0. 001）. However, the VEQD2-S Gyof lung using VMAT was 4.51% higher than that of 5F-IMRT,whieh was lower than the 7. 58% when the phys- ical dose was used. CONCLUSION Combined with the EQDz-dosimetri

关 键 词：食管癌 调强放射治疗 等效生物剂量 线性二次模型 

分 类 号：R735.1[医药卫生—肿瘤]