三种照射技术在髓母细胞瘤放射治疗中的剂量学分析

摘要

Objective We aimed to explore the difference of dosimetry among intensity modulated radia-tion therapy(IMRT),volumetric modulated arc therapy(VMAT)and helical tomotherapy(TOMO)in the radio-therapy of medulloblastoma.Methods Ten children's patients with the medulloblastoma were selected and de-signed in this study.A clinically feasible radiotherapy plan was designed for IMRT(5 fields),VMAT and TOMO. Conformality index(CI),homogeneity index(HI),V107,maximum dose(Dmax),organ at risk(OAR)dose-volume level,monitor units and treatment time were used to analyze in these groups.Results CI,HI,V107,Dmaxand OAR of target areas were significantly superior to VMAT and IMRT in the TOMO group of target PTV for whole brain full radiotherapy.The organ at risk dose-volume level in the TOMO group was lower than that in VMAT and IM-RT(5 fields)groups(P<0.05).The TOMO group also had the most monitor units and the longest treatment time (P<0.05).Hence,the patients in the TOMO group could irradiate completely the whole brain and full spinal cord without moving treatment couch to avoid the error from the man-made movement in VMAT and IMRT(5 fields)treatments.Conclusion In the radiotherapy of medulloblastoma,the dose distribution of patients in the TOMO group are superior to the VMAT and IMRT groups(5 fields).However,the number of monitor units and treatment time is significantly increased during treatment,and its clinical effect needed to be further studies.%目的 探讨调强放射治疗(Intensity modulated radiation therapy,IMRT)、容积调强弧形放疗(Volumetric modulated arc therapy,VMAT)和螺旋断层放射治疗(Helical tomotherapy,TOMO)在髓母细胞瘤放射治疗中的剂量学差异.方法 选取10例髓母细胞瘤儿童患者,设计出IMRT(等分5野)、VMAT(双弧)、TOMO三组放疗计划.分析三种计划靶区的适形指数(CI)、均匀指数(HI)、1.07倍处方剂量线所包含的靶区体积(V107)、靶区内最大剂量点剂量值(Dmax)、危及器官(OAR)受量情况、机器跳数和治疗时间.结果 对于全脑全脊髓放疗,TOMO组计划靶区PTV的CI、HI、V107、Dmax和OAR受量都优于VMAT组和IMRT(5野)组计划(P<0.05);TOMO组计划机器跳数最多(P<0.05),且其治疗时间最长(P<0.05);TOMO组可以一次完成全脑全脊髓照射,避免了VMAT和IMRT(5野)治疗时人为移床误差.结论 在髓母细胞瘤放射治疗中,TOMO组在剂量分布上优于VMAT组和IMRT(5野)组,但其治疗时机器跳数和治疗时间明显增加,它对临床上的影响有待于进一步观察与研究.