容积旋转调强技术在乳腺癌根治术后放射治疗中的应用  

Feasibility of volumetric modulated arc therapy applied to breast cancer radiotherapy after radical surgery

作　　者：姜庆丰[1] 柏森[2] 傅玉川[2] 李光俊[2] 张洪[2] 艾平[2] 李贤富[1] 谭榜宪[1] 

机构地区：[1]川北医学院附属医院肿瘤科,四川南充637000 [2]四川大学华西医院肿瘤中心,四川成都610041

出　　处：《川北医学院学报》2012年第2期102-108,共7页Journal of North Sichuan Medical College

基　　金：四川省教育厅重点项目(10ZA077)

摘　　要：目的:应用容积旋转调强放射治疗技术(volumetric modulated arc therapy,VMAT)于乳腺癌改良根治术后的辅助放疗,探索VMAT在乳腺癌根治术后放射治疗中的可行性及潜在优势。方法:30例乳腺癌改良根治术后拟放疗患者行CT扫描,照射靶区包括胸壁及锁骨上淋巴引流区,处方剂量为50 Gy/25次;ADAC Pinnacle9.0放射治疗计划系统设计切线野三维适形治疗计划和VMAT计划,Elekta公司Synergy直线加速器执行计划;比较两种计划的靶区及重要危及器官(肺、心脏、对侧乳腺、甲状腺、肱骨头等)剂量学参数及计划执行效率。结果:切线野适形计划及VMAT计划均能满足临床治疗需求,双90°弧段VMAT计划较单240°弧段或单360°弧段有更优的靶区剂量分布。VMAT计划靶区适形度指数和均匀性指数优于CRT,分别为0.63:0.44和1.11:1.15,差异具有显著性。VMAT分别降低患侧肺平均V20、V30、V40体积8%、10%、11%;但VMAT组患侧肺低剂量区V5平均增加16%,V10则差异无显著性。心脏平均剂量VMAT和CRT分别为5.2 Gy和4.1 Gy。心脏高于20 Gy、30 Gy的体积VMAT:CRT分别为3%:5%、1%:3%。心脏、全肺及除靶区以外的正常组织平均受照射低剂量区(≤10 Gy)体积VMAT高于CRT组,高剂量区(≥20 Gy)体积VMAT低于CRT组。VMAT治疗时间平均为152(107～214)s,CRT治疗时间平均为231(152～434)s,差异有统计学意义,P<0.05。每分次治疗平均机器跳数分别为VMAT(450 MU)、CRT(489 MU),差异有统计学意义,P<0.05。结论:VMAT应用于乳腺癌改良根治术后的放疗是可行的,VMAT较CRT有更优的靶区剂量分布和更小的危及器官高剂量受照体积。对类似乳腺的偏人体中心的放疗靶区,采用两段小角度VMAT治疗弧,可以改善靶区的剂量分布。VMAT可以缩短治疗时间,提高患者舒适性和放疗工作效率。Objective：To assess the potential dosimetric advantages and drawbacks of volumetric modulated arc therapy（VMAT） to arc shaped targets of breast cancer after modified radical mastectomy compared to three-dimension conformal radiotherapy（3-D CRT）.Methods：Thirty female patients with breast cancer,who underwent modified radical mastectomy,were selected.VMAT and conformal tangential fields radiotherapy treatment plans were designed to encompass plan target volume（PTV） of the chest wall and anterior supraclavicular area.A dose of 50 Gy in 25 fractions was prescribed.By comparing the target coverage and organs at risk（OARs）,the dose and treatment efficiency of the two type plans were developed to assess the advantages of the VMAT.Results：VMAT plans had a more uniform target dose distribution with average Conformation Number（CN）of 0.63 compared to 0.44 of the 3-D CRT plans.Two short arc have better dose uniformity compared to one full arc in VMAT.VMAT reduce ipsilateral lung（Ipsi-L） average V20,V30,V40 as 8.0 %,10.0 %,11.0 %,respectively.VMAT increase Ipsi-L average V5 from 47 % to 63 %,and increase contralateral lung（Cont-L） V2.50 from 2.0 % to 13.0 % compare to CRT.A larger volume of low irradiated dose levels in normal tissue which included lung and heart generated in the VMAT plans.The VMAT improved treatment efficiency by treatment time 152 s（107～214 s）,and monitor units 450 MU compared with CRT 231 s（152～434 s）,and 489 MU.Conclusion：The VMAT plans generate more uniformity in the target dose and spare more higher dose level in normal tissue compared to the 3-D CRT.VMAT application to radiotherapy of breast cancer after modified radical surgery is feasible.

关 键 词：容积旋转调强 三维适形 放射治疗 乳腺癌 剂量学 

分 类 号：R472[医药卫生—护理学]