CR在全身照射定位和肺部挡铅的摆位误差

Set-up error of CR in total body irradiation localization and lung shielding

目的探讨计算机x射线成像（CR）在全身照射（TBI）定位和肺部挡铅验证中的摆位误差。方法使用TOR18FG测量其相同条件下kV级和MV级x射线能量的图像质量，建立其临床应用流程，并分析摆位误差。结果在TBI治疗条件下，MV级的x射线图像的低对比度分辨率和空间分辨率远较kV级的差，但可以比较清晰地识别高对比度组织，并应用于TBI治疗。头脚方向误差为：腹背（AP）方向，左肺（0．50±1．65）cm，右肺（1．16±1．56）cm；（背腹）PA方向，左肺（1．12±2．22）cm，右肺（0．41±2．16）cm。左右两侧方向误差为：AP方向，左肺（0．81±1．19）cm，右肺（0．43±1．20）cm；PA方向，左肺（0．31±1．64）cm，右肺（0．55±1．49）cm。结论通过CR的应用，提高了TBI的治疗摆位精度。

Objective To investigate the set-up error of CR in total body irradiation localization and lung shielding. Methods TOR 18FG software was employed to measure the image quality of images at kV and MV levels. The clinical processes were established and the positioning error was analyzed. Results The low contrast resolution and spatial resolution of MV level images were much worse than those at kV level in the condition of total body irradiation, but the image at MV level could be used to identify the high contrast tissues and employed in total body irradiation. The longitudinal errors were （0. 50 ±1.65） cm for left lung and （ 1.16 ±1.56）cm for right lung in AP direction, while （ 1.12 ±.22）cm and （0. 41 ±. 16） cm respectively in PA direction. The errors of lateral were （0.81 ±1.19）cm for left lung and （0. 43 ±1.20）era for right lung in AP direction, while （0. 31 ±1.64）cm and （0. 55 ±1.49）cm respectively in PA direction. Conclusions Application of CR in total body irradiation could make positioning in treatment much easily and reduce the localization errors.