食管癌影像引导的放射治疗六维配准范围探讨

Study on 6-dimensional registration scope of esophageal cancer during image-guided radiotherapy

目的探讨食管癌在影像引导下进行放射治疗(IGRT)时的六维最佳配准范围。方法20例食管癌病人,其中男性18例,女性2例;年龄27～68岁,平均年龄45岁。病灶部位食管胸上段2例,食管胸中段18例。在IGRT的摆位误差纠正前,行锥形束计算机X线断层摄影术(CBCT)图像扫描,并选取不同的配准范围与计划CT图像进行图像配准。以手动配准为基准,比较使用骨配准方式对4种配准范围:椎体、椎体+棘突、椎体+肺尖、椎体+棘突+肺尖等的配准结果的差异。结果用4种配准范围进行配准与手动配准比较,在平移方向上的Z轴平移中椎体配准最差,其余相似。平均差异的幅度以椎体+棘突+肺尖配准为最小。在旋转方向的X轴旋转中,椎体+棘突+肺尖配准有优势,其余各种方法均相似。差异的幅度从小到大为椎体+棘突>椎体+棘突+肺尖>椎体>椎体+肺尖配准。结论食管癌骨配准时最佳的配准范围是椎体+棘突+肺尖。

Objective To explore the 6-dimensional registration scope of esophageal cancer during image-guided radiotherapy （IGRT）. Methods A total of 20 patients with esophageal cancer were enrolled,male 18 and female 2,aged 27-68 years,mean age 45 years. There were 2 cases in upper thoracic esophagus and 18 cases in middle thoracic esophagus. Cone beam computed tomography（CBCT） images were acquired before IGRT. The registration between CBCT images of 4 different kinds of registration scope and the planned CT images of esophageal cancer were performed and compared by manual match with 4 different kinds of registration scope match eg. vertebra; vertebra and spinous process; vertebra and the apex of lung; vertebra,spinous process and the apex of lung. Results Compared by manual match with 4 kinds of registration scope match,on translational movement,there was statistical difference in vertebra match at Z translational movement,but the other scopes were similar. The average of differences in scopes of translational movement of vertebra,spinous process and the apex of lung match was minimal. On rotational movement,vertebra,spinous process and the apex of lung match had the superiority at X rotational movement,but in the other methods were similar. The difference in scope of translational movement was as follows：vertebra and the apex of lung match 〉 vertebra match 〉 vertebra,spinous process and the apex of lung match 〉 vertebra and spinous process match. Conclusion The best scope of registration for patients with esophageal cancer during IGRT is the registration of the vertebra,spinous process and the apex of lung.