滑轨CT图像引导技术在胸中上段食管癌放疗中的应用研究

Application of CT image-guided technology in radiotherapy of the mid-and upper-thoracic esophageal carcinoma

目的 将滑轨CT图像引导技术应用于胸中上段食管癌放疗，计算在线CT图像引导和非在线CT引导这两种因素各自的靶区外扩边距。方法 100例胸中上段食管癌计划进行调强放疗的患者，每次放疗前进行CT扫描并与计划CT图像配准比较分析，获得分次间摆位误差数据，并在线修正；根据系统选样法选取50例患者，增加治疗后的CT扫描以分析修正后的误差、治疗中的位移、分次内肿瘤（GTV）位移。结果 与非在线CT图像引导相比，采用在线CT图像引导使得靶区外扩边距在左右、头脚、腹背方向由8.8、9.1和6.1 mm降低到4.1、4.5和4.3 mm。结论 应用在线 CT 图像引导能显著提高靶区精准度，缩小靶区外扩边距。

Objective To compare the clinical target volume （CTV） expanding margins in the mid-and upper-thoracic esophageal carcinoma during radiotherapy measured with and without online image guidance technique by CT on rail. Methods100 patients with mid-and upper-thoracic esophageal carcinoma undergoing intensity modulated radiotherapy received CT scanning.Image registration was conducted between the scanning results and the planned CT images, thus set-up error data were acquired and got on-line correction. Fifty patients were randomly selected to undergo additional post-treatment CT scanningso as to analyze the revised residuals, displacement during treatment, and infra-fraction GTV shifts. Results Compared to the radiotherapy without CT-based image guidance, the CTV expanding margins obtained with CT-based image guidance was reduced significantly from 9.1, 8.8 and 6.1 mm to 4.1, 4.5 and 4.3 mm in the left-right, head-feet, and belly-back directions respectively. Conclusions The on-line image-guided technology significantly improves the accuracy of target and reduces the CTV expanding margins.