32例鼻咽癌调强放疗摆位误差的简单分析

摘要

目的:利用电子射野影像验证系统(electronic portal imaging device,EPID)监测鼻咽癌调强放射治疗的摆位误差,为临床医生的计划靶区(planning target volume,PTV)勾画与外放提供参考数据.方法:随机选取32例接受调强放疗的鼻咽癌患者,利用电子射野影像验证系每周一次统获取患者正侧位图像(electronic portal image,EPI),在iView GT系统下与患者首次计划设计时的数字化重建图像(digitally reconstructed radiograph,DRR)进行对照比较,计算摆位误差.结果:左右x轴方向误差为1.36 mm±1.02 mm,前后y轴方向误差为1.23 mm±1.05 mm,上下z轴方向误差为:1.34 mm±1.08mm.结论:32例鼻咽癌患者治疗时三个方向的摆位误差均小于5mm,严格执行摆位质量控制前提下,这个数据可以用于指导临床医生从内靶区放外5mm产生PTV,这样既能保证患者的肿瘤受到完全的照射,同时也能保护更多的正常组织避免不必要的照射.%Objective: To investigate setup errors during intensity modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) and provide setup margin reference to clinic by EPID (electronic portal imaging device). Methods: Thirty-two NPC patients were enrolled in this study, whose electronic portal images were acquired weekly, patient's setup errors were analyzed by iVewGT software. Results: The average setup errors of NPC patients' were 1.36 mm±1.02 mm in left-right direction, 1.23 mm±1.05 mm in superior-inferior direction and 1.34 mm±1.08 mm in anterior-posterior direction. Conclusions: Thirty-two patients setup errors in this study are all less then 5 mm. The data can be used for guidance to expand from ITV to PTV, this can ensure that the patient's target is totally irradiated and protect the more normal tissue to avoid unnecessary irradiation.