伽玛刀、IMRT、VMAT治疗复发高级别胶质瘤剂量学分析

Dosimetric Analysis of Gamma Knife,IMRT and VMAT in Treatment of Recurrent High-Grade Gliomas

目的通过分析复发高级别脑胶质瘤患者行伽玛刀、固定野调强放疗(Intensity Modulated Radiation Therapy,IMRT)、容积弧形调强放疗(Volumetric Modulated Arc Therapy,VMAT)的剂量学差异,探讨3种放疗方式的优缺点。方法选取中国人民解放军海军第九七一医院2020年1月至2022年1月进行放疗的19例复发性高级别脑胶质瘤患者为研究对象,在治疗计划系统中设计伽玛刀、固定野IMRT和VMAT治疗计划,其中固定野IMRT和VMAT分别设计靶区均匀剂量计划和靶区同步增量(Simultaneous Integrated Boost,SIB)计划(SIB-IMRT、SIB-VMAT),且要求处方剂量包含95%体积。评价参数包括低剂量区V5、脑部放射坏死指标V12、靶区适形指数(Conformity Index,CI)、靶区均匀指数(Homogeneity Index,HI)、靶区最大剂量(Dmax)、平均剂量(Dmean)以及梯度指数。结果5种治疗计划中,SIB-IMRT的V5低于固定野IMRT和SIB-VMAT(P值均<0.05);伽玛刀的V12最低(P值均<0.05),SIB计划比常规计划(SIB-IMRT vs.固定野IMRT、SIB-VMAT vs.VMAT)的V12低(P值均<0.05)。固定野IMRT与VMAT、SIB-IMRT与SIB-VMAT靶区的CI差异无统计学意义(P值均>0.05),均优于伽马刀(P<0.05)。伽玛刀与SIB-IMRT、SIB-VMAT靶区的HI和Dmean差异无统计学意义(P值均>0.05)。结论伽玛刀对正常脑组织的保护作用更好,对于复杂靶区适形度稍差。固定野IMRT和VMAT适形度更高,其中,SIB-IMRT、SIB-VMAT能达到类似伽玛刀的靶区剂量分布,且正常脑组织受量较常规调强放疗更低。

Objective By analyzing the dosimetric differences of gamma knife,fixed field intensity modulated radiation therapy(IMRT)and volumetric modulated arc therapy(VMAT)in patients with recurrent high-grade glioma,to discuss the advantages and disadvantages of the three radiotherapy methods.Methods A total of 19 patients with recurrent high-grade gliomas who received radiotherapy in No.971 Hospital of The People’s Liberation Army Navy from January 2020 to January 2022 were selected as the study objects.The gamma knife,fixed field IMRT and VMAT treatment plans were designed in treatment planning system.Fixed field IMRT and VMAT were designed target uniform dose plan and target simultaneous integrated boost(SIB)plan(SIB-IMRT,SIB-VMAT)respectively,requiring the prescription dose to contain 95%volume.The evaluation parameters included low-dose area V5,brain radiation necrosis index V12,target conformal index(CI),target homogeneity index(HI),target maximum dose(Dmax),average dose(Dmean)and gradient index.Results Among the five treatment plans,the V5 of SIB-IMRT was lower than that of fixed field IMRT and SIB-VMAT(both P<0.05);The V12 of gamma knife was the lowest(all P<0.05),and The V12 of SIB plan were lower than that of conventional plan(SIB-IMRT vs.fixed field IMRT,SIB-VMAT vs.VMAT)(all P<0.05).There was no statistically significant difference in CI between fixed field IMRT and VMAT,SIB-IMRT and SIB-VMAT(all P>0.05),and all better than gamma knife(all P<0.05).There was no statistically significant difference in HI and Dmean between gamma knife and SIB-IMRT,SIB-VMAT(both P>0.05).Conclusion The protective effect of gamma knife on normal brain tissue is better,but the conformal degree of complex target area is slightly worse.The conformal degree of fixed field IMRT and VMAT is higher,and SIB-IMRT and SIB-VMAT can reach the target dose distribution similar to gamma knife,and the dose of normal brain tissue is lower than that of conventional IMRT.