右乳腺癌术后放疗中VMAT和dIMRT的剂量学比较

Dosimetric Comparison Between VMAT and dIMRT for Right Breast Carcinoma Postoperation Radiotherapy

目的:比较VMAT(快速旋转容积调强)和dIMRT(固定野动态调强)在右乳腺癌术后放疗计划中的剂量学差异。方法:利用瓦里安Eclipse 10.0计划系统对6例右乳腺癌术后患者,分别设计单弧与双弧VMAT计划和4野dIMRT计划,在计划满足临床要求的前提下,利用剂量体积直方图(DVH)统计比较GTV和PTV的相关剂量参数、适形指数(CI),肺、脊髓、正常组织的剂量体积参数,以及机器总跳数(MU)、总治疗时间(T)。结果:本研究中单弧与双弧VMAT计划和4野dIMRT计划的GTV和PTV的相关剂量参数D2、D98、Dmean、CI均无统计学差异(P>0.05),但是VMAT计划的靶区适行度略高于dIMRT计划;右肺的V5、V10、V20、V30均有统计学差异(P<0.05,其中V5的P值小于0.001);左肺的V5有统计学差异(P<0.05),V10、V20、V30无统计学差异(P>0.05);心脏的V10、V30均无统计学差异(P>0.05);脊髓的D1、Dmean均有统计学差异(P<0.05,其中D1的P值小于0.001);机器总跳数(MU)、总治疗时间(T)均有统计学差异(P<0.001)。结论:三种治疗计划均能满足临床要求,VMAT计划靶区适行度略高于dIMRT计划,肺的V5、V10有所增加,V20、V30有所降低,同时脊髓D1、Dmean也有所增加,但是在右乳腺癌术后放疗计划中脊髓的剂量整体在一个较低的水平,不用优先考虑;此外VMAT计划能够明显减少机器总跳数和总治疗时间,单弧计划的平均机器总跳数和总治疗时间分别为dIMRT计划的59.7%、31.6%,双弧计划的平均机器总跳数和总治疗时间分别为dIMRT计划的61.0%、57.8%。综合考虑,笔者认为单弧VMAT计划应该是右乳腺癌术后放疗的首选。

Objective： To compare the dosimetric difference between VMAT （RapidArc）and dlMRT （fixed gantry angle dynamic IMRT）for right breast carcinoma postoperation radiotherapy. Methods： Therapy For 6 right breast carcinoma postoperation cases, RapidArc plan （single arc and double arc） and dlMRT plaza （four fields） were generated by Varian Eclipse 10.0 treatment planning system.Comparative endpoints were planning target volume （PTV and GTV）dose,doses to surrounding structures,number of monitor units （MU） ,and treatment delivery time. Results： In the study of RapidArc plan （single arc and double arc） and dIMRT plan, there were significant differences（GTV and PTV dose parameters）in D2,D98,Dmean,CI （P〉0.05）, But VMAT plans target conformal was slightly higher than dlMRT plan; Right lung V5,V10,V20,V30 were statistically significant （P〈0.05） ; Left lung V5 were significantly different （P〈0.05）, V10 ,V20、V30 no significant difference （P〉0.05）;Heart V10,V30 were not statistically different （P〉 0.05） ;Spinal cord D1, Dmean were statistically significant （P〈 0.05）;Number of monitor units （MU） and treatment delivery time were statistically significant （P〈0.001）. Conclusions： Three treatment plans can meet the clinical requirements, VMAT plans target conformal was slightly higher than dIMRT, lung V5,V10 increased, V20,V30 decreased, spinal cord D1,Dmean also increased, but the spinal cord at a lower dose level in the whole of the Right breast cancer radiotherapy planning, do not give priority; VMAT plans can significantly reduce the number of monitor units and treatment delivery time,comparison with dlMRT plans,the average of single arc in planned the number of monitor units and treatment delivery time was 59.7%, 31.6%, the average of double arc in planned the number of monitor units and treatment delivery time was 61.0%, 57.8%. Overall, I believe that single arc VMAT plans should be the right choice for right breast carcinoma postoperation radiotherapy.