直肠癌静态调强与容积旋转调强放疗计划的剂量学对比研究  

Dosimetric comparison of the VMAT and IMRT planning in rectal carcinoma

作　　者：李润霄[1] 迟子锋[1] 曹彦坤[1] 景仲昊 王京[1] 张若辉 韩春[1] 李振生[1] 

机构地区：[1]河北医科大学第四医院放疗科,石家庄050011

出　　处：《中华放射医学与防护杂志》2015年第2期123-127,共5页Chinese Journal of Radiological Medicine and Protection

摘　　要：目的 对比研究直肠癌术后患者应用静态调强放疗（IMRT）和容积旋转调强放疗（VMAT）的计划质量、治疗效率和剂量精度,为临床治疗技术的选择提供参考依据.方法 选择10例直肠癌术后调强放疗患者,行CT模拟定位并勾画靶区及危及器官,在同一计划系统上给予相同处方剂量和目标优化条件,分别设计5野IMRT计划和双弧VMAT计划.比较两种计划的靶区（PTV/CTV）受量、适形指数（CI）、均匀指数（HI）、危及器官（OAR）的受量、机器跳数、治疗计划执行时间,以及剂量验证通过率.结果 两种治疗计划均能满足临床剂量要求,VMAT计划的靶区剂量覆盖率略低于IMRT计划.VMAT和IMRT计划的HI分别为0.095和0.101,差异无统计学意义（t=2.61,P＞0.05）;而IMRT计划的CI（0.737）优于VMAT计划（0.614）（=4.94,P＜0.05）,考虑为VMAT计划优化过程中对周围正常组织低剂量区受量限制过于严格,从而造成计划的适形度受到影响.VMAT计划中正常组织如膀胱、股骨头的低剂量区较之IMRT计划均有不同程度增加.VMAT和IMRT计划的平均机器跳数（MUs）分别为599和515（t=4.72,P＜0.05）,相应的治疗时间分别为201和304 s（=5.83,P＜0.05）.使用Delta4对两种计划进行验证,y通过率（选用3％/3 mm标准）分别为VMAT 93.13％和IMRT 96.00％（t=3.75,P＜0.05）.结论 直肠癌VMAT和IMRT计划均可满足临床要求,VMAT计划可以显著降低治疗时间,提高治疗效率,但其疗效还需进一步临床评估.Objective To compare the plan quality and dose precision of volumetric modulated arc therapy（VMAT） plans with intensity modulated radiation therapy （IMRT） plans in rectal carcinoma.Methods In 10 patients,five-field IMRT plans were compared to two dual arcs VMAT plans.All the patients underwent surgery and CT simulation orientation,target volumes and normal tissues were drawn in the images.Plans were optimized by Oncentra 4.3 planning system and designed with the same optimize parameters.Plans were normalized so that 95% of PTV would receive the prescription dose of 50 Gy in 25 fractions.Dose-volume histograms and isodose distributions were evaluated.Conformity indices （CI）,homogeneous indices （HI）,total segments,monitor units （MUs）,delivery time were also compared.Measurements of the plan dose distribution were performed and analyzed with Delta4 detector array by γ method.Results Both plans could meet target dose specifications and normal tissue constraints.VMAT plan achieved better CI than IMRT plans,CIVMAT =0.614,CIIMRT =0.737,the differences were statistically significant （t =4.94,P 〈 0.05）.The HI of the VMAT plan was 0.095 compared to 0.101 of IMRT plans,without statistically significant differences （t =2.61,P 〉 0.05）.In the normal tissue including bladder and femurs,there was an increase in the volume receiving low dose radiation in VMAT.The number of MU was reduced from 599 in VMAT plans to 515 in IMRT plans（t =4.72,P 〈 0.05）,but VMAT plan had a significantly shorter delivery time （201 s） compared with 304 s in IMRT plans （t =5.83,P 〈 0.05）.In the dose verification,an average of 93.13% of the detector points passed the 3%/3 mm γ criterion for VMAT plans,while in IMRT plans the dose verification was 96% （t =3.75,P 〈 0.05）.Conclusions VMAT and IMRT techniques can both achieve a good PTV coverage,HI and CI.VMAT offers shorter treatment delivery time than IMRT for rectal carcinoma,enhances the efficiency of treatment.Further clinical evaluation of VMAT wou

关 键 词：直肠癌 静态调强 容积调强 剂量验证 危及器官 Delta4探测阵列 

分 类 号：R735.37[医药卫生—肿瘤]