Objective To investigate the accuracy of two different image registration algorithms for the setup errors in treatment of head and neck tumor with image- guided radiation therapy (IGRT). Methods Forty nine head and neck cancer pa-tients underwent radiation therapy with Elekta Synergy linear accelerator. KV- CBCT was applied to investigate the setup discrep-ancy before treatment, after online correction and at the end of delivery. Translational and rotational setup errors in the direction of X, Y, Z, and GX, GY, GZ were analyzed by applying two different image registration methods:the bone- based registration and grey- based registration. Statistical analysis was conducted to compare the difference between two imaging registration methods. Results Total of 109 sets of CBCT images were scanned for 49 patients with head and neck cancer. The setup errors with bone- based registration and grey- based registration in the translational direction of the X, Y, and Z axis were (0.127 ± 0.143) cm and (0.002 ± 0.147) cm, (- 0.086 ± 0.169) cm and (0.084 ± 0.183) cm, (- 0.057 ± 0.175) cm and (- 0.060 ± 0.158) cm, re-spectively. The setup in rotational direction of GX, GY, and GZ for bone- based and grey- based registration were (0.751 ± 1.390)°and (0.534 ± 1.374)°, (0.033 ± 1.870)°and (0.064 ± 1.870)°, (- 0.079 ± 1.486)°and (0.028 ± 1.147)°, respective-ly. Except in the rotational GX direction, there were no significant differences between bone- based and grey- based registration algorithm. Conclusion Both bone- based and grey- based registration can be selected in image- guided radiation therapy (I-GRT) for patients with head and neck cancer. It is suggested that the bone alignment be selected first and gray registration can be auxiliary if necessary.%目的探讨头颈部肿瘤图像引导放射治疗（IGRT）不同图像配准方法对摆位误差的影响。方法利用Elekta Syner-gy直线加速器放射治疗49例头颈部肿瘤患者，利用机载锥形束CT(CBCT)XVI系统对患者进行治疗前摆位扫描、在线调整后扫描和治疗结束后扫描。对重建获得的CBCT图像与治疗计划系统CT图像进行骨性和灰度两种模式匹配，分析X、Y、Z轴水平方向的误差及GX、GY、GZ的旋转方向误差，比较两种匹配模式之间的差异。结果49例患者分别进行109次CBCT扫描，其中骨性配准和灰度配准在X轴水平方向的误差分别为（0.127±0.143）、（0.002±0.147）cm；在Y轴水平方向的误差为（-0.086±0.169）、（0.084±0.183） cm；在Z轴水平方向的误差为（-0.057±0.175）、（-0.060±0.158）cm。骨性配准和灰度配准在X轴旋转方向的误差分别为（0.751±1.390）°、（0.534±1.374）°；在Y轴旋转方向的误差为（0.033±1.870）°、（0.064±1.870）°；在Z轴旋转方向的误差为（-0.079±1.486）°、（0.028±1.147）°。两种配准方式除了在X轴旋转方向有统计学差异（P＜0.05）外，其他5个方向的误差数据均无统计学差异（均P＞0.05）。结论头颈部肿瘤进行IGRT时，两种配准方式均可选择，建议首先使用骨性配准，必要时灰度配准辅之。
展开▼
