CT在影像引导下放疗中应用的历史与现状

三维适形放疗（3-DCRT）、束流调强放疗（IMRT）以及质子放疗等现代放疗技术的主要优势是肿瘤靶区剂量分布适形性的提高，但这同时也意味着肿瘤靶区与周围正常组织的剂量梯度的增加。在应用这些技术进行放疗时，放疗实施过程中的微小的误差都可能造成肿瘤靶区的低剂量和周围正常组织的高剂量照射，不仅使这些技术本身的优势没有得到发挥，反而会造成正常组织损伤增加，更为严重的是肿瘤靶区的“漏照”。所以，强调精确实施放疗计划的影像引导下放疗成为3-DCRT、IMRT以及质子放疗等现代放疗技术发挥优势的重要保证。CT作为三维影像引导工具，在影像引导下放疗概念的革新和应用中扮演着重要的角色，本文主要回顾和介绍CT在影像引导下放疗中的应用历史及现状，同时也希望对影像引导下放疗的概念作一诠释。

Advances in clinical application of CT in the image-guided radiotherapy

Three-dimensional conformal radiotherapy with intensity-modulated radiation beams significantly enhances the ability to produce sharp dose gradients in the boundaries between a tumor and nearby critical structures. Small uncertainties in the daily repositioning of patients can lead to the overdose of the critical structure and the escape of the target volume. It emphasizes the need to improve the ability to localize the target for treatment. And the image-guided radiotherapy was development. Although steady streams of enhanced new methods of lmaging are being introduced to improve treatment guidance and treatment verification, the development of kilovohage cone-beam CT integrated with the medical linear accelerator for the specific purpose of guiding therapy will permit localization and targeting of soft-tissue structures at the time of treatment. In this review, we focus on the clinical application of CT in the image-guided radiotherapy.