鼻咽癌放疗摆位重复性分析

Research on Set-up Repeatability in Radiotherapy for Nasopharyngeal Carcinoma

目的:研究病人在放疗中的误差情况及技术员在摆位重复性及摆位误差范围,确定CTV与PTV间扩边大小。方法:选择鼻咽癌(NPC)采用IMRT治疗的患者50名,利用EPID验证系统进行每周一次机下误差验证,共300次摆位,获得600张机下验证片,并通过iViewGT系统下验证片与PLATO.PTSV2.6.4系统下重建所得的DRR片进行对照得出综合误差。结果:综合摆位误差范围0-4mm;1mm以内占55%,2mm以内占89%,3mm以内占98%,3mm以上2%。结论:鼻咽癌放疗摆位误差基本可以控制在3mm以内,CTV与PTV扩边范围至少3mm,符合我院NPC照射野设计要求。

Objective：To investigate the set -up error in intensity modulated radiotherapy （IMRT） and the repeatability of positioning, analye the range of set - up error and estimate the margin required for CTV - PTV. Methods：Selecting 50 NPC patients treated by IMRT and check the set - up error weekly using EPID for a total of 300 times, got 600 pictures. Then calculated the set - up error by comparing the pictures with the DRR using the iViewGT system. Results：The range of set- up errors was 0 -4mm, .55% ≤1mm, 89% ≤2mm, 98%≤3mm, 2% 〉 3 mm. Conclusion：The set -up errors of NPC patients are controlled in 3 nun, the margin required for CTV -PTV is 3mm.