【摘要】 目的:研究胸部肿瘤三维适形放疗的摆位误差大小和影响因素,为胸部肿瘤适形放疗计划设计时CTV外放PTV提供参考数据。方法:21例胸部肿瘤患者接受三维适形放疗。男12例,女9例。其中食管癌9例,肺癌7例,乳腺癌5例。首次摆位后,去掉体膜,在患者体表沿激光十字画出三个等中心点的坐标位置,并以该三个坐标为标准坐标,测量前后、头脚、左右方向摆位误差。每例病例连续测量5次,共计摆位105次。所有病例分为两组,A组11例,测量55次,未在体表标记体膜相对位置。B组10例,测量50次,CT模拟定位时在体表标记体膜相对位置。结果:人与人间以及次与次间均存在一定差别。头脚方向摆位误差最大,腹背方向次之,左右方向最小。B组摆位误差左右方向为(2.2±1.9)mm,头脚方向为(4.3±2.6)mm,腹背方向为(2.6±1.7)mm。与A组比较,误差在Y、Z方向有显著性差异。结论:CT模拟定位时,在体表标记体膜的相对位置可减少三维适形放疗的摆位误差。胸部放疗的CTV-PTV扩边范围(MPTV)应适当扩充为左右方向5.4mm、头脚方向8.3mm和腹背方向5.5mm。更多还原

【Abstract】 Objective:To study the spatial distribution of set-up errors for thoracic neoplasm patients treated with three-dimensional conformal radiation therapy (3DCRT) and to provide referential safe margins out of clinical tumor volume (CTV) in treatment plan design.Methods:Twenty-one thoracic neoplasm patients with 10 cases of esophagus carcinoma,6 cases of lung cancer and 5 cases of breast cancer entered this study,including 12 male and 9 female patients.Removed thermoplastic cast after first set-up,marked the coordinate of isocenter point along the laser lines and measured the distance from the laser lines cross to the coordinate axis five times every patients after treatments,21 patients were divided into group A without the mark of the position of thermoplastic cast and group B with the mark of the position of thermoplastic cast on body surface.There were 55 and 50 measurements in group A and group B respectively.Results:Set-up errors always existed and differ from patients to patients and time to time.The set-up error was the largest in superior-inferior direction,moderate in the anterior-posterior direction,smallest in the left-right direction.The errors of group B were (2.2±1.9)mm in the left-right direction,(4.3±2.6)mm in superior-inferior direction and (2.6±1.7)mm in the anterior-posterior direction.There were significant differences between group A and B in the errors of superior-inferior direction and anterior-posterior direction.Conclusion:Marking the position of thermoplastic cast could reduce the set-up errors greatly.The margin of PTV was suggested 5.4mm in the left-right direction,8.3mm the anterior-posterior direction and 5.5mm in the anterior-posterior direction.更多还原