肺癌影像引导放疗摆位误差及配准的对比研究

摘要

Objective To explore the setup error and area registration error during lung cancer radiotherapy by using the on board imager (OBI) of the linear accelerator. Methods Totally 50 lung cancer patients underwent image-guided radiation therapy. Then OBI system was used for the scan validation by electronic portal imaging device (EPID) and cone beam CT (CBCT), and comparative analysis was executed on the setup errors of EPID and CBCT. Results The translation errors of EPID were (-1.62 ±1.58), (2.12 ±1.49) and (4.52 ±2.42)mm respectively at Lat, Vrt and Lng directions, while those of CBCT were (-1.27±1.25), (1.43±1.57) and (3.12±2.62) mm respectively. The registration errors at Lat, Vrt and Lng directions and rotation angle of lung tissue were (-1.27±1.25), (1.43±1.57), (3.12±2.62)mm and (0.5±1.6)° respectively, and those of target area were (-1.56±1.78), (1.68±2.39), (3.42±2.73)mm and (0.8±1.9)° respectively. CBCT and EPID had statistical differences (P<0.05) in setup error validation as well as setup errors at Vrt and Lng directions. There were no significant differences (P>0.05) when CBCT self-registration was involved in selecting different areas. Conclusion CBCT and EPID can both used for the setup validation of lung cancer, while the former behaved better than the latter.%目的:利用直线加速器的OBI(on board imager)影像引导系统对肺癌放疗摆位误差及区域配准误差进行分析研究.方法:选取50例行影像引导放射治疗肺癌患者,应用OBI影像引导系统进行二维电子射野影像(electronic portal imaging device,EPID)和三维锥形束CT(cone beam CT,CBCT)扫描验证,对比分析2种验证方式的摆位误差.利用OBI影像引导系统配准分析软件分别对肺组织和靶体积进行自动配准,对比分析靶中心上各方向的位置误差.结果:EPID和CBCT 2种摆位验证方式下左右(Lat)、上下(Vrt)、头脚(Lng)方向的平移误差分别为(-1.62±1.58)、(2.12±1.49)、(4.52±2.42)mm和(-1.27±1.25)、(1.43±1.57)、(3.12±2.62)mm;在不同区域(肺组织和靶体积)配准中的位置误差左右(Lat)、上下(Vrt)、头脚(Lng)方向的平移误差及旋转角度分别为(-1.27±1.25)、(1.43±1.57)、(3.12±2.62)mm,(0.5±1.6)°和(-1.56±1.78)、(1.68±2.39)、(3.42±2.73)mm,(0.8±1.9)°.CBCT与EPID在肺癌摆位误差验证分析中具有统计学差异(P<0.05),在上下、头脚方向2种方式的摆位误差差别较大,在CBCT自动配准不同区域选择上无统计学意义(P>0.05).结论:在肺癌摆位验证中,2种方法均可用于临床,CBCT优于EPID.