螺旋断层和旋转调强技术在小细胞肺癌脑预防放射治疗海马保护的剂量学研究

摘要

Objective: To explore and discuss the dosimetric characteristic of TOMO and Rapid Arc technique on prophylactic cranial irradiation of hippocampal avoidance for small cell lung cancer so as to provide basis for choosing ideal radiotherapy technique in clinical practice.Methods: 8 patients with small cell lung cancer in limited stage were enrolled,and the planning target volume(PTV)was whole brain except hippocampi decrement region(external expansion 5mm from hippocampi region),and the prescription dose was 25 Gy/10F,and two kinds of plan(TOMO and RapidArc)were designed.Through the statistics of dose volume histogram(DVH)to analyze dose parameter of target region and each organ at risk(OAR),and evaluate machine hop count and treatment time of treatment plan.The pair t test was adopted to analyze between group comparison.Results: The Dmean and HI of TOMO were significantly better than that of Rapid Arc,respectively(t=3.512,t=3.594,P＜0.05).And the Dmaxand Dmean of left and right hippocampal of TOMO planning were significantly lower than that of Rapid Arc planning(t=13.254,t=4.545,t=19.656,t=4.533,P＜0.05),respectively.And the Dmax of left and right crystal,Dmax of left and right optic nerve,Dmax of left and right optic chiasma,Dmaxof brainstem and Dmax of left inner ear of TOMO planning were significantly lower than that of Rapid Arc planning(t=16.912,t=26.043,t=4.495,t=3.451,t=4.495,t=3.378,t=3.444,P＜0.05),respectively.While the differences of Dmax of left and right eyeball and Dmax of right inner ear between two plans were no significant(t=0.256,t=0.496,t=1.289,P＞0.05),respectively.On the curative efficiency,the curative time of TOMO was longer than that of Rapid Arc.Conclusion: Both of TOMO and Rapid Arc can achieve clinical requirement on prophylactic cranial irradiation about hippocampal-avoidance,and TOMO has advantages on dose distribution of target region and hippocampal and normal tissue-avoidance.And the advantages of RapidArc are shorter curative time and higher efficiency.%目的:探讨螺旋断层(TOMO)和旋转调强(RapidArc)技术在小细胞肺癌脑预防放射治疗海马保护的剂量学特点,为临床选择理想的放射治疗技术提供依据.方法:选取8例局限期小细胞肺癌患者,计划靶区(PTV)为全脑避开海马减量区(海马外扩5 mm),处方剂量为25 Gy/10 F,分别设计TOMO和RapidArc两种计划,通过剂量体积直方图(DVH)统计分析靶区和各危及器官的剂量参数,并评估治疗计划的机器跳数和治疗时间.组间对比采用配对t检验.结果:TOMO计划靶区PTV的Dmean及靶区剂量均匀指数(HI)优于RapidArc计划,且差异有统计学意义(t=3.512,t=3.594;P＜0.05);TOMO计划左右海马的Dmax和Dmean明显低于RapidArc计划,差异有统计学意义(t=13.254,t=4.545,t=19.656,t=4.533;P＜0.05);TOMO计划的左右晶体Dmax、左右视神经Dmax、视交叉Dmax、脑干Dmax及左内耳Dmax均低于RapidArc,差异有统计学意义(t=16.912,t=26.043,t=4.495,t=3.451,t=4.495,t=3.378,t=3.444;P＜0.05);左右眼球Dmax和右内耳Dmax差异无统计学意义(t=0.256,t=0.496,t=1.289;P＞0.05);在治疗效率上,TOMO治疗时间长于RapidArc.结论:TOMO和RapidArc计划在海马保护脑预防放射治疗均可达到临床要求,TOMO计划在靶区剂量分布、海马和正常组织保护具有一定的优势;而RapidArc计划治疗时间短,效率高.