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目的:分析计算机断层扫描(CT)模拟校位过程中的摆位误差,探索提高精确定位的有效措施。方法:随机选取我科2014年1月-12月胸部肿瘤患者15例进行CT模拟校位测量误差并分析(肺癌12例、胸腺肿瘤2例、食道癌1例)。校位过程中进行2次摆位后扫描等中心图像层面,测量图像等中心点至体表坐标数值与放射治疗计划单DRR图像比较,计算x轴(AB)、y轴(GT)、z轴(腹、背)方向的摆位误差。结果:15例第1次与第2次摆位扫描等中心层面图像与计划单DRR图像比较(x、y、z)轴平均误差分别为(2.69±1.15)mm,(3.53±1.74)mm,(1.86±1.67)mm;(1.76±0.86)mm,(2.07±0.13)mm,(1.65±1.13)mm。显示第2次摆位误差在重新调整体位后比第1次减小,以y轴(GT)方向为显著,x轴(AB)方向略小,z轴(腹、背)方向最小,摆位前后相比,差异具有统计学意义(P<0.05)。结论:热塑成型体模固定下CT模拟校位经过2次认真摆位后可以减小误差。
OBJECTIVE: To analyze the setup error during computer-aided calibration of computed tomography (CT) and to explore effective measures to improve the accuracy of positioning. Methods: Fifteen cases of thoracic tumors from January 2014 to December 2014 in our department were randomly selected and analyzed. The errors were measured and analyzed (12 cases of lung cancer, 2 cases of thymus tumor and 1 case of esophageal cancer). In the process of schooling, the images of the center of the center of the scan such as the center of the scan and the coordinate of the body surface were compared with the DRR images of the radiotherapy plan after scanning for 2 times, and the x-axis (AB), y-axis (GT) (Abdominal, back) the orientation of the error. Results: The mean (x, y, z) axis errors of central and axial DR images were (2.69 ± 1.15) mm and (3.53 ± 1.74) mm, respectively, (1.86 ± 1.67) mm; (1.76 ± 0.86) mm, (2.07 ± 0.13) mm, (1.65 ± 1.13) mm respectively. The results show that the error of the second setup is smaller than that of the first one after the readjustment of the posture, which is significant in the direction of the y-axis (GT), slightly smaller in the x-axis (AB) direction and smallest in the z- Before and after comparison, the difference was statistically significant (P <0.05). Conclusion: Thermoplastic molding phantom fixed CT simulated school after two serious positioning error can be reduced.