中文摘要：

目的分析评价鼻腔NK/T细胞淋巴瘤在螺旋断层放疗（helical tomotherapy,HT）与常规静态调强放疗（IMRT）2种治疗技术中剂量学特点。方法对10例局限性Ⅰ～Ⅱ期鼻腔NK/T细胞淋巴瘤患者,统一给予靶区剂量50Gy/25次,对每例患者分别实施设计HT和IMRT计划。比较靶区、危及器官剂量分布情况。结果 HT组平均适形度指数为0.81,平均均匀性指数为1.08,均明显好于IMRT组（平均适形度指数为0.71,平均均匀性指数为1.12）（t=8.22,t=-4.81,P〈0.05）。HT组晶体、腮腺和脑干的最大剂量与平均剂量均小于IMRT组,HT组腮腺的V5、V10和V15低于IMRT组,而HT组视神经的最大剂量、平均剂量、V20、V30和V40均高于IMRT组,但无统计学意义。结论 HT和IMRT计划均有较好的靶区剂量分布,但HT技术较IMRT技术明显改善了靶区剂量分布适形度,降低了晶体等正常组织受照剂量,可使患者从中获益,其临床意义有待进一步研究。

英文摘要：

Objective To compare the dosimetric characteristics of helical tomotherapy（HT） and step-and-shoot intensity modulated radiotherapy（IMRT） for nasal T/NK-cell lymphoma.Methods Ten patients with stage I and II nasal T/NK-cell lymphoma were enrolled in this study.HT and IMRT plans were developed for each patient with CT images.The prescribed dose was 50 Gy/25f for PTV.The dose distributions of targets,organs at risk（OARs） were analyzed and compared.Results The mean conformity index（CI） and the mean homogeneity index（HI） in HT group（0.81 and 1.08） were better than those in IMRT group（0.71 and 1.12）（respectively,t=8.22,t=-4.81,P〈0.05）.The Dmax and Dmean of lens,parotids and brainstem in HT were lower than those in IMRT.The V5、V10 and V15 of parotids were lower in HT than in IMRT group.The Dmax,Dmean,V20,V30 and V40 of left and right optical nerves in HT were higher than in IMRT,and they were not statistically significant.Conclusion HT plans have a better homogeneity,steeper dose gradient,and a better protection for lens and other normal tissues,comparing with IMRT plans.So it would benefit patients.The clinical significance of the dosimetric differences needs further study.