局部复发鼻咽癌患者再程放疗技术的剂量学参数比较

目的： 比较容积旋转调强（VMAT）、固定野调强（IMRT）和三维适形（3D-CRT）放疗技术在局部复发鼻咽癌患者治疗中的剂量学参数，分析3种治疗计划的剂量学特性。方法:选择12例局部复发的鼻咽癌患者，采用Pinnacle 9.2和eciseplan 2.03治疗计划系统，每例患者均设计VMAT﹑IMRT和3D-CRT ，比较3组计划的剂量分布及危及器官受量等。结果: MAT及IMRT组适形度指数（CI）相似，但均优于3D-CRT组，组间比较差异有统计学意义（P<0.05）。3组计划的靶区不均匀指数（HI）相近，组间比较差异无统计学意义（P>0.05）。3D-CRT组机器跳数(MU)及出束时间优于其他2组，VMAT组优于IMRT组，组间比较差异均有统计学意义（P<0.05）。危及器官受量，3组计划脑干及晶体受量比较差异无统计学意义（P>0.05）；VMAT组和IMRT组脊髓、视神经、视交叉和大脑颞叶的受量明显优于3D-CRT组，组间比较差异有统计学意义（P<0.05），但VMAT组与IMRT组比较差异无统计学意义（P>0.05）。 结论： 3种放疗技术的治疗计划剂量分布有差异,VMAT与IMRT计划均能较好覆盖靶区，并减少周围正常组织受量，满足临床需求。VMAT计划的靶区适形度、MU和出束时间优于IMRT计划。3D-CRT仅在MU和治疗时间上有优势。

Comparison of dosimetric parameters of re-irradiation in patients with locally recurrent nasopharyngeal carcinoma

Abstract:Objective To compare the dosimetric parameters of volumetric modulated arc therapy（VMAT）,fixed field intensity modulated radiation therapy（IMRT） and three-dimensional conformal radiotherapy（3D-CRT）in the radiotherapy for the patients with locally recurrent nasopharyngeal carcinoma,and to analyze their characteristics.Methods Twelve patients with locally recurrent nasopharyngeal carcinoma were treated with VMAT,IMRT and 3D-CRT plan designed by Pinnacle 9.2 and Preciseplan 2.03 treatment planning system.The dosimetric parameters of targeted volumes and organs at risk were compared between three groups.Results The conformation indexes(CI) of VMAT and IMRT plans were similar,and they were both better than 3D-CRT plan,the difference was significant（P<0.05）.The homogeneity index(HI) in three groups were similar,there were no statistically significant differences between them(P>0.05).The monitor units(MU) and beam time in 3D-CRT group were bettethose in other two groups,and VMRT group was better than IMRT group,the statistical differences were observed between three groups（P<0.05）.There were no statistical differences of organs at risk such as brainstem and lens between three groups（P>0.05）.The doses of the spinal cord,optic nerve,optic chiasm and temporal lobe of brain in VMAT and IMRT groups were better than those in 3D-CRT group,there were statistical differences between them（P<0.05）,and the data in VMAT and IMRT groups were similar,and there were no statistical differences（P>0.05）.Conclusion There are differences of the targeted dose distribution between the three kinds of radiation technology,while VMAT and IMRT plans can cover the targeted areas and reduce the received doses of organs at risk.The CI,MU and beam time of VMAT plan are better than those of IMRT plan.3D-CRT plan only has advantage in the MU and beam time.