肺癌图像引导放疗不同配准方式对摆位误差的影响

目的：探讨图像引导肺癌放射治疗（以下简称放疗）时不同图像配准方法对摆位误差的影响。方法：利用Elekta Synergy直线加速器对43例肺癌患者进行基于锥形束CT（CBCT）的图像引导放疗（IGRT）。将重建获得的CBCT图像与原计划系统CT图像进行骨性和灰度两种模式匹配,分析X、Y、Z轴水平方向的摆位误差及旋转方向摆位误差,比较两种匹配模式之间的差异。结果：43例肺癌放疗共进行114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（-0.297±3.137）mm、（0.377±2.958）mm;在Y轴水平方向的误差为（-1.415±5.313）mm、（0.719±5.451）mm;在Z轴水平方向的误差为（0.632±3.033）mm、（-0.679±2.982）mm。骨性配准和灰度配准在X轴旋转方向的误差分别为（-0.469±1.605）°、（-0.493±1.461）°;在Y轴旋转方向的误差为（-0.203±1.431）°、（0.35±1.424）°;在Z轴旋转方向的误差为（0.134±1.478）°、（0.196±1.348）°。将6个方向摆位误差计量数据配对进行统计学处理,骨性配准和灰度配准两种配准方式除了在X轴旋转和Z轴旋转差异无统计学意义（均P〉0.05）外,其他4个方向的摆位误差计量数据差异均有统计学意义（P〈0.05）。结论：肺癌行IGRT时,两种配准方式均可选择,建议首先使用灰度配准,骨性配准辅之。

Comparative study on set-up errors with different registration algorithm for lung cancer undergone image guided radiation therapy

Objective： To investigate the accuracy of two different image registration algorithms for the set-up error study in the treatment of lung cancer with image-guided radiation therapy （IGRT） technique.Methods：Forty-three lung cancer patients were treated with cone beam CT （CBCT） undergone image guided. Elekta Syner-gy linear accelerator radiation （KV-CBCT） was applied to investigate the setup discrepancy before the treatment, after online correction and the end of delivery. The difference in bone alignment, and grey value alignment were compared between CBCT images obtained by the reconstruction and original plan system CT images. The rota-tional error of the X, Y, Z-axis in the horizontal direction and the error of X, Y, Z in rotation direction were ana-lyzed.Results： Total of 114 sets of CBCT images were scanned for 43 patients with lung cancer. The setup errors with bone-based registration and grey-based registration in the translational direction of the X, Y, and Z axis were （-0.297±3.137） mm and （0.377±2.958） mm, （-1.415±0.5.313） mm and （0.719±5.451） mm, （0.632±3.033）mm and （-0.679±2.982） mm. The setup in rotational direction of GX, GY, and GZ for bone-based and grey-based registration were （-0.469±1.605） ° and （-0.493±1.461） °, （-0.203±1.4 31） ° and （0.35±1.424） °, （0.134±1.478） ° and （0.196±1.348） °. Except in the rotational X and Z direction, there was signiifcant difference between bone-based and grey-based registration algorithm.Conclusion： The two registrations all can be selected in lung cancer treatment with image guided radiation therapy （IGRT）. It is suggested that the bone registration auxiliary after gray alignment is necessary.