论文部分内容阅读
[目的]应用医科达Synergy系统的锥形束CT(cone beam computed tomography,CBCT)研究腹盆部肿瘤患者在放疗分次内的摆位误差变化情况。[方法]对17例腹盆部肿瘤患者进行治疗,每次照射前进行首次摆位的CBCT扫描,然后与计划CT图象进行匹配,获得平移方向(x、y、z)和旋转方向(u、v、w)的摆位误差,通过完全由计算机控制的全碳素纤维六足遥控床进行自动的摆位误差纠正,误差调整后再次获取CBCT图像,分析并记录误差纠正后的残留误差。当患者治疗结束后,第三次获取CBCT图象,分析治疗后的体位误差,并与治疗前误差纠正后的残留误差相比较,从而得出患者在治疗过程中的分次内摆位误差情况。[结果]17例患者进行CBCT扫描672次,每次治疗开始前首次摆位、误差纠正后和治疗结束后的CBCT扫描均为224次。治疗前误差纠正后的系统误差(均数)±随机误差(标准差)在x、y、z、u、v、w六自由度方向上分别为(0.01±0.36)mm、(-0.40±0.65)mm、(-0.01±0.63)mm、(0.1±0.5)°、(0.1±0.5)°、(0.0±0.4)°,患者治疗结束后测量的误差分别为(-0.01±0.51)mm、(-0.77±0.84)mm、(-0.10±0.70)mm、(0.1±0.6)°、(0.1±0.5)°、(0.0±0.4)°;配对t检验y、z方向差异显著,P值分别为:0.000、0.041。[结论]腹盆部肿瘤在治疗过程中存在一定的分次内摆位误差,这在临床上设计PTV的摆位扩边应予以考虑。
[Objective] To study the change of setting error of radiotherapy and radiotherapy in patients with abdomen tumor using cone beam computed tomography (CBCT) of Synergy system. [Method] Seventeen patients with abdominal pelvic tumors were treated. The first CBCT scan was performed before each irradiation and then matched with the planned CT images to obtain the translational directions (x, y, z) and the rotation direction (u , V, w). The error was corrected and the CBCT image was acquired again. The residual error after the error correction was analyzed and recorded. CBCT images were obtained for the third time after the patient’s treatment was completed, the position error after treatment was analyzed and compared with the residual error after the correction of the error before treatment, so as to obtain the position error during the treatment . [Result] Sixteen times CBCT scans were performed in 17 patients. The first time before each treatment, CBCT scans after error correction and after treatment were both 224 times. The systematic error (mean) after correction of pre-treatment error ± standard deviation was (0.01 ± 0.36) mm and (-0.40 ± 0.65) respectively in the six degrees of freedom directions of x, y, z, ), (-0.01 ± 0.63) mm, (0.1 ± 0.5) °, (0.1 ± 0.5) ° and (0.0 ± 0.4) ° respectively. The measured errors after treatment were (-0.01 ± 0.51) mm and -0.77 ± 0.84 mm, (-0.10 ± 0.70) mm, (0.1 ± 0.6) °, (0.1 ± 0.5) ° and (0.0 ± 0.4) ° respectively. Paired t test showed significant difference between y and z directions, P values were : 0.000,0.041. [Conclusion] Abdominal pelvic tumors have some errors during the treatment, which should be taken into account in clinical design of PTV.