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目的:应用电子射野影像系统分析我院行盆腔适形调强放疗病人的摆位误差情况,为临床上计划靶区(PTV)的设定提供参考依据。方法:选取行盆腔适形调强肿瘤病人21例,应用电子射野影像系统对每例患者每周分别拍摄正侧射野图像各1张,共获取210张图像,分别将图像与计划系统所形成的相应数字重建影像(DRR)进行比较,获取上下(X轴)、左右(Y轴)、前后(Z轴)方向的摆位误差。结果:21例患者X轴、Y轴、Z轴各方向的系统误差的标准差分别1.02,2.37,1.94mm,随机误差的标准差分别是1.35,2.24,2.30mm。X轴、Y轴、Z轴的摆位扩边值分别为3.49,7.51,6.46mm。结论:尽管应用真空垫、热塑网膜等体位固定方法,但由于各种原因,盆腔肿瘤放疗仍有一定的摆位误差,在设定盆腔靶区时建议左右、上下、前后分别外扩3.5,8,7mm。
OBJECTIVE: To analyze the placement error of patients with pelvic conformal intensity modulated radiation therapy in our hospital by using electronic radiography imaging system, and to provide reference for the setting of clinical planning target area (PTV). Methods: Twenty-one cases of patients who undergone CRT with pelvic resonance were selected. Each patient was photographed with positive radiographs one by one each week, and 210 images were obtained. The images and planning system The corresponding digital reconstruction images (DRRs) are compared to obtain the setup errors in the up and down (X axis), left and right (Y axis) and fore and aft (Z axis) directions. Results: The standard deviations of systematic errors in X axis, Y axis and Z axis in each of the 21 patients were 1.02, 2.37 and 1.94 mm respectively. The standard deviations of random errors were 1.35, 2.24 and 2.30 mm respectively. X-axis, Y-axis, Z-axis placement expansion values were 3.49,7.51,6.46 mm. CONCLUSIONS: Despite the application of vacuum cushion, thermoplastic net and other body fixation methods, due to various reasons, there are still some errors in setting up pelvic tumor radiotherapy. When setting the pelvic target area, it is suggested to expand it by 3.5 , 8,7mm.