肿瘤快速旋转调强放疗摆位误差的测量与分析

摘要

Objective: To investigate the set-up errors in the treatment of different regions by using kilovoltage cone-beam computed tomography scanning technique of linear accelerator airborne. Methods: 180 patients were treated with the Varian RapidArc linear accelerator,including 53 head and neck tumors、58 thoracic tumors and 69 Pelvic tumors.All the patients were scanned by kilovoltage cone-beam computed tomography before the first radiotherapy and afterward once a week.The acquired CBCT images were co-registered with planning CT and setup errors of iso-center positions on the axes of x,y and z were obtained for statistical analyses.Corresponding CTV to PTV margins were also calculated. Results: The systemic± random errors on lateral (x),veitical(y)and longitudinal (z)directions were(0.55±0.79)mm, (0.81±1.00)mm,( 1.21±1.12)mm for the head and neck tumors; (1.13±1.26)mm, (1.03±1.09)mm, (2.12±2.15)mm for the thoracic tumors; (0.94±1.16)mm, (0.87±1.08) mm, (2.02±1.78)mm for the Pelvic tumors,respectively. The systemic± random errors on the rotational deviations were (0.39±0.48)° for the head and neck tumors ;(0.47±0.54)° for the thoracic tumors ;(0.44±0.51)° for the Pelvic tumors,respectively. Conclusions: Using CBCT can decrease positioning errors and ensure high radiotherapy precision.%目的:采用直线加速器机载的千伏级锥形束CT扫描技术对不同部位肿瘤患者的摆位误差进行探讨.方法:应用瓦里安RapidArc直线加速器治疗肿瘤患者180例,其中头颈部患者53例,胸部患者58例,盆腔患者69例.所有患者在首次放疗前行KV-CBCT扫描,以后每周扫描1次.将CBCT扫描图像和计划CT图像及其靶中心匹配,分析靶中心在x、y、z方向上的误差值及其误差分布情况,探讨我科CTV-PTV外放边界大小.结果:系统误差(均数)±随机误差(标准差)在平移误差Lateral左右(x)方向、Vertical背腹(y)方向、Longitudinal头脚(z)方向分别为头颈部x(0.55±0.79)mm,y(0.81±1.00)mm,z(1.21±1.12)mm;胸部x(1.13±1.26)mm,y(1.03±1.09)mm,z(2.12±2.15)mm;盆腔x(0.94±1.16)mm,y(0.87±1.08)mm,z(2.02±1.78)mm;绕y轴方向旋转(Rtn)误差分别为头颈部(0.39±0.48)°,胸部(0.47±0.54)°,盆腔(0.44±0.51)°.结论:CBCT可以减少分次治疗间的摆位误差,保证放疗摆位精度.