目的:比较鼻咽癌精确放疗中应用KV级锥形束CT(kV-CBCT)不同配准方法对治疗中配准偏差的影响，为鼻咽癌图像引导下放疗选择更优的配准方法提供依据。方法：随机选取2021年02月-2021年10月在我科实施精确放疗的鼻咽癌患者10例，应用E1ekta SynergyTMIGRT加速器机载kV-CBCT对其进行位置验证，首次治疗前及之后的每周一次扫描验证，将其与定位时图像进行配准。每次CBCT图像均分别进行骨性与灰度配准，并记录自动配准的结果，最后由医生、物理师共同参与手动调整摆位误差值，确认后发送到机器进行治疗。将两种不同配准方式的结果跟医生确认后的标准数值对比得到各自偏差值再行分析。结果：骨性配准相对于灰度配准在面背方向（Z）相对偏差更小（0.588±0.473 vs 0.885±0.670，P<0.05）；以1 mm偏差值为界区分配准优劣，同样面背方向（Z）骨性配准优的比例高于灰度配准（88% vs 70%，P<0.05）。而左右（X）、头脚（Y）方向差异无统计学意义（P均>0.05）。结论：鼻咽癌精确放疗三维验证时，应用CBCT图像配准中应以骨性配准为主，同时查看GTV或PTV的配准结果，从冠状位、矢状位和横断位等多方面比对微调后才能得到相对满意的配准结果。
关键字：鼻咽肿瘤；放射治疗；图像引导放疗；锥形束CT；图像配准；线性误差
Abstract：
Objective: To investigate the effect of different registration methods on the registration deviation of kilovoltage cone beam CT(kV-CBCT) in precise radiotherapy for nasopharyngeal carcinoma, and to provide a basis for selecting a better registration method for image guided radiotherapy for nasopharyngeal carcinoma. Methods: Ten patients with nasopharyngeal carcinoma who received precise radiotherapy in our department from February 2021 to October 2021 were randomly selected. The E1ekta SynergyTMIGRT accelerator kV-CBCT was used to verify the position of the patients. Each CBCT image was registered with bone and gray scale respectively, and the results of automatic registration were recorded. Finally, doctors and physicists participated in manual adjustment of the setup error value, and then sent to the machine for treatment. The results of the two different registration methods were compared with the standard values confirmed by the doctors to obtain their own deviation values and then analyzed. Results: Compared with gray-scale registration, the relative deviation in the dorsal face direction (Z) was smaller in the bone registration (0.588±0.473 vs 0.885±0.670, P< 0.05); When 1 mm deviation was used as the boundary, the proportion of excellent registration in the same dorsal face (Z) direction was higher in the bone registration than in the gray scale registration (88% vs 70%, P< 0.05). However, there was no significant difference in the left-right (X) and superior-inferior (Y) directions (P > 0.05). 0.05). Conclusions: In the three-dimensional verification of precise radiotherapy for nasopharyngeal carcinoma, the application of CBCT image registration should focus on bone registration, and the registration results of GTV or PTV should be checked at the same time. Only after fine-tuning the alignment from the coronal, sagittal and transverse positions can relatively satisfactory registration results be obtained.
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