Objective:To study the dosimetry discrepancy for thoracic cervical esophageal cancer intensity modulated radiation therapy (IMRT) treatment planning with different energy X rays on tumor target and normal tissue,and search more suitable energy X rays for thoracic cervical esophageal cancer intensity modulated radiation therapy (IMRT).Methods:42 cases with esophageal cancer were selected,the Pinnacle3 8.0 m treatment planning system were used respectively to design treatment plan with different energy X ray:6 MV and 10 MV,while the optimization parameters and other treatment planning parameters was constant.The Compare parameters were:95％ volume dose(D95),5％volume dose(D5),Conformal index(CI),homogeneity index (HI) for PTV,maximum dose(Dmax) of spine cord,500 cGy、1000 cGy、2000 cGy、3000 cGy dose volume(V5,V10,V20,V30) and mean dose(Dmean)of lungs,mean dose(Dmean) and 3000 cGy、4000 cGy volume dose(V30、V40) of the heart.Results:There was a different for dosimetry discrepancy of PTV's Dmean,HI,CI,D95 and D5 (P＞0.05) between 6 MVX group and 10 MVX group There was no statistically significant for dosimetry discrepancy of heart's Dmean and V~.spinal cord's Dmax,V20 and V30 double lung(P＜0.05); the dosimetry discrepancy for normal tissue (CT scan covers body minus PTV,namely B-P),V20,V31.5have statistical significance.Conclusions:The dose distribution between 10 MVX planning group and 6 MVX planning group are similar,however the dose to organs at risk like heart、spine cord、lungs and skin were inferior to which in 6 MVX planning group.%目的:研究在胸中上段食管癌调强计划(IMRT)设计中不同能量的X线对肿瘤计划靶区PTV及危及器官的影响,探寻更适合的能量.方法:选择42例胸中上段食管癌患者,采用Pinnacle3 8.0 m治疗计划系统,对每例患者分别采用6MVX线和10MVX线两种能量,在相同布野方案和优化参数情况下分别进行IMRT计划设计并进行剂量学比较.比较的参数有:PTV的95％体积的剂量(D95)和5％体积的剂量(D5)、适形指数(CI)、均匀指数(HI)和脊髓的最大剂量(Dmax),双肺的500 cGy、1000 cGy、2000 cGy、3000 cGy剂量体积(V5,V10,V20,V30)和平均剂量(Dmean),心脏的平均剂量(Dmean)和3000 cGy、4000 cGy剂量体积(V30V40)等.结果:在靶区剂量参数方面,6MVX线计划组与10MVX线计划组PTV的Dmean、HI、CI、D95、D5差异无统计学意义(P＞0.05)；对于危及器官,心脏的Dmean、V30,脊髓的Dmax,双肺的V20、V30差异有统计学意义(P＜0.05)；对于正常组织B-P的V20、V31.5差异有统计学意义(P＜0.05).结论:胸中上段食管癌调强计划中,采用10MVX线计划组的调强计划与6MVX线计划组的靶区剂量分布相似,但心脏、脊髓、肺和皮肤等危及器官的受照剂量较低.
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