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目的分析比较锥形束CT(CBCT)与MOSAIQ两系统用于测量胸部放射治疗(放疗)摆位误差情况。方法 2011年2月-9月,随机选择21例用热塑模固定的胸部调强治疗患者,进行同次摆位的CBCT图像采集和电子射野影像(EPID)正侧位图像采集。将CBCT图像与定位CT图像进行匹配,图像经iViewGT系统传输至MOSAIQ系统图像处理模块中与计划生成的数字重建图像(DRR)正侧位片进行匹配,分别记录两套系统图像匹配结果在X(左右)方向、Y(头脚)方向、Z(前后)方向的平移误差及CBCT的旋转误差值,计算其均值、标准差,进行统计学处理。结果本研究共获取图像106组,每组内包含一次CBCT图像和EPID图像。CBCT和MOSAIQ系统下EPID匹配结果平移误差在X、Y、Z方向分别为(0.103±0.240)cm、(0.086±0.342)cm、(0.017±0184)cm和(0.005±0.214)cm、(0.004±0.0.315)cm、(0.113±0.239)cm;旋转误差在X、Y、Z方向分别为(0.792±1.173)°、(0.130±1.407)°、(0.793±0.960)°,其中≤3°的概率分别为98.2%、97.2%、99.1%,最大绝对值分别为5°、3.4°、3.3°。两套系统在X、Y、Z三个方向的平移误差经配对样本检验,在Y方向P>0.05,在X和Z方向上P值均<0.05,两系统的测量差值有直线负相关关系。结论 CBCT和EPID在测量胸部放疗靶区中心的平移误差中差异有统计学意义,因此建议在做胸部放疗时有CBCT的情况下应优先使用。
Objective To analyze and compare the errors of chest radiotherapy (radiotherapy) setup by using cone beam CT (CBCT) and MOSAIQ systems. Methods From February to September 2011, 21 patients undergoing thermomechanical fixation of chest twitch were randomly selected for CBCT image acquisition and electronic radiography (EPID) lateral image acquisition. The CBCT images were matched with the CT images. The images were transmitted to the MOSAIQ system image processing module by the iViewGT system for matching with the planned digital reconstruction images (DRR). The results of two images matching were recorded in X ( Left and right) direction, Y (head and foot) direction, Z (front and back) direction of translation error and CBCT rotation error value, calculate the mean value, standard deviation, for statistical analysis. Results A total of 106 images were obtained in this study, each containing a CBCT image and an EPID image. The translational errors of the matching results of EPID under CBCT and MOSAIQ were (0.103 ± 0.240) cm, (0.086 ± 0.342) cm, (0.017 ± 0184) cm and (0.005 ± 0.214) cm in the X, (0.792 ± 1.173), (0.130 ± 1.407) ° and (0.793 ± 0.960) °, respectively, with the rotation error of ≤3 ° The probabilities were 98.2%, 97.2% and 99.1%, respectively. The maximum absolute values were 5 °, 3.4 ° and 3.3 °, respectively. The translational errors of the two systems in the three directions of X, Y and Z were tested by paired samples. P> 0.05 in the Y direction and P <0.05 in the X and the Z directions. The difference between the two systems has a linear negative correlation . Conclusions The CBCT and EPID have statistical significance in the measurement of translational errors in the center of the target area of chest radiotherapy. Therefore, it is suggested that CBCT should be given priority in the case of chest radiotherapy.