千伏级CBCT图像引导椎体肿瘤放疗摆位误差分析

目的:研究千伏级CBCT图像引导椎体肿瘤放疗摆位误差的研究。方法:采用瓦里安IX直线加速器机载影像系统对37例椎体肿瘤患者调强放疗前行CBCT，系统自动重建图像并与治疗计划CT图像相匹配，获得患者X轴(左右）、Y轴（头脚）、Z轴（前后）方向摆位误差。结果:椎体肿瘤37例行114次扫描，只考虑误差大小时X轴、Y轴、Z轴方向误差分别为（2.69±2.46） mm、(5.37±4.57) mm、(4.02±3.5) mm。其中胸椎（2.02±2.07） mm、（4.80±4.59） mm、（4.00±3.92） mm，腰椎（3.35±2.65） mm、（5.83±4.54） mm、（4.03±3.08） mm。结论:腰椎患者与胸椎患者相比，摆位误差左右方向较大，在摆位中应加以注意，以减少治疗摆位误差。

Study of set-up errors with kV cone-beam computed tomography images guide radiotherapy for vertebral metastatic carcinoma

Objective:To study the set-up error of vertebral carcinoma radiotherapy guided by kV CBCT scans in our hospital.Methods:37 patients with vertebral carcinoma,were under IMRT(intensity-modulated radiation therapy).All patients were given CBCT scans before treatment by Varian IX linear accelerator airborne imaging system.The system reconstructed image automaticly and matched the CT image of treatment plan.We could achieve the set-up error of right-left(X),anterior-posterior(Y),superior-interferior(Z) directions.Results:37 patients with vertebral carcinoma were underwent 114 times of CBCT scans.When only concerdered the error magnitude,the error at right-left(X),anterior-posterior(Y),superior-interferior(Z) directions were（2.69±2.46） mm,(5.37±4.57) mm,(4.02±3.5) mm,respectly.Among which,the set-up error of thoracic vertebra cancer were （2.02±2.07） mm,（4.80±4.59） mm and（4.00±3.92） mm， lumbar vertebra cancer were（3.35±2.65） mm,（5.83±4.54） mm and（4.03±3.08） mm.Conclusion:During the radiotherapy of vertebral carcinoma patinets,the set-up error of the lumbar vertebra is larger than that of the thoracic vertebra in the right-left(X) direction,so attention should be paid to set-up so as to reduce the treatment error.