鼻咽癌适形放射治疗不同固定方法对摆位精度的影响

目的]探讨鼻咽癌放射治疗两种不同固定方法摆位误差值的大小 ,为设计PTV提供参考数据。方法]面膜固定组20例 ,泡沫枕尼龙带固定20例 ,按放疗处方规范摆位 ,每周在模拟机下拍片一次 ,与定位片比较误差大小。结果]等中心点误差值面膜组为(0.94±1.47)mm,泡沫枕尼龙带固定组为(1.38±1.94)mm。结论]①面膜组摆位误差明显低于普通组(P<0.01) ;②设计PTV时 ,不同固定方法 ,预留范围应有所区别 ,面膜组可定为3mm ,普通组为5mm。以免漏照射或造成不必要照射

Influence of Setup Error by Different Immobilization Methods in Conformal Radiotherapy for Nasopharyngeal Carcinoma

To study the influence of setup errors by different immobilization methods in conformal radiotherapy for nasopharyngeal carcinoma(NPC).Twenty cases with NPC were immobilized by masque and another 20 cases by nylon ribbon(conventional modality).X film was taken per week with the treatment position in simulator for each patient,then comparing these films with primary simulation film ,and setup errors were measured.The mean setup error for isocenter deviation was 0.94mm in the masque group and 1.39mm in the conventional group,P<0.01.Conclusions]The setup error is significantly lower in masque group than that in conventional group.Using masque system is helpful to determine the appropriate PTV margin in conformal radiotherapy for NPC.