文章：

影像引导放射治疗的创新

Innovations in image-guided radiotherapy

原文发布日期：2007-12-01

DOI: 10.1038/nrc2288

类型: Review Article

开放获取: 否

要点：

1. In order to assure proper coverage of the clinical target volume (CTV) by radiation, a margin needs to be added to compensate for daily positioning errors and internal motion of organs, resulting in the planning target volume (PTV). The PTV therefore includes normal tissues near the tumour, to which radiation is intentionally delivered.
2. The dose of radiotherapy that is necessary to control a tumour is often not delivered because of a high probability of complications in nearby normal tissues. This problem can be tackled by the generation of conformal dose distributions that tightly match the volume of the PTV and/or by decreasing the amount of normal tissue in the PTV.
3. Image-guided radiotherapy (IGRT) is defined as frequent imaging in the treatment room that allows treatment decisions to be made on the basis of these images. IGRT aims at decreasing CTV-to-PTV margins from centimetres to millimetres.
4. The synergy between conformal radiotherapy (CRT) and IGRT has drastically improved the quality of radiotherapy and has broadened its possibilities and indications. Clinical implementations of CRT–IGRT have enabled dose escalation, conformal sparing and non-uniform dose distributions, and initiated a revision of fractionation schedules.
5. Research to improve image quality in radiotherapy is not new, but developments of software to quantify target localization errors, on the basis of in-room imaging and hardware allowing automated set-up, have stimulated mainstream clinical application of IGRT.
6. IGRT makes use of many different imaging techniques, using modalities ranging from planar imaging to fluoroscopy to cone-beam CT, and following procedures as simple as using a single set-up image or as complex as intra-fraction tumour tracking.
7. IGRT can be applied for managing of inter-fraction as well as intra-fraction geometric set-up uncertainties and for adapting treatments to tumour responses.

要点翻译：

1. 为确保临床靶区（CTV）得到充分的放射覆盖，需设定一个边界以补偿日常摆位误差和器官内部运动，从而形成计划靶区（PTV）。因此PTV包含了肿瘤附近的正常组织，这些组织会被有意纳入照射范围。
2. 由于邻近正常组织发生并发症的风险较高，常无法施以控制肿瘤所需的放射剂量。该问题可通过以下方式解决：生成与PTV体积紧密匹配的适形剂量分布，和/或减少PTV内的正常组织含量。
3. 图像引导放疗（IGRT）指在治疗室内进行频繁成像，并基于这些图像制定治疗决策。IGRT旨在将CTV至PTV的边界从厘米级缩减至毫米级。
4. 适形放疗（CRT）与IGRT的协同作用显著提升了放疗质量，并拓展了其应用范围与适应症。CRT–IGRT的临床实施实现了剂量递增、适形保护和非均匀剂量分布，并推动了分次放疗方案的革新。
5. 提升放疗图像质量的研究并非新课题，但基于室内成像量化靶区定位误差的软件开发及实现自动化摆位的硬件进步，共同推动了IGRT的临床主流应用。
6. IGRT采用多种成像技术，包括从平面成像到透视成像再到锥形束CT等模式，其流程既可采用单次摆位图像这样的简单操作，也可实施如分次内肿瘤追踪般的复杂程序。
7. IGRT既可用于管理分次间与分次内的几何摆位不确定性，也能根据肿瘤反应调整治疗方案。

英文摘要：

The limited ability to control for the location of a tumour compromises the accuracy with which radiation can be delivered to tumour-bearing tissue. The resultant requirement for larger treatment volumes to accommodate target uncertainty restricts the radiation dose because more surrounding normal tissue is exposed. With image-guided radiotherapy (IGRT) these volumes can be optimized and tumoricidal doses can be delivered, achieving maximal tumour control with minimal complications. Moreover, with the ability of high-precision dose delivery and real-time knowledge of the target volume location, IGRT has initiated the exploration of new indications for radiotherapy, some of which were previously considered infeasible.

摘要翻译： 

对肿瘤位置的控制能力有限，削弱了放疗照射肿瘤组织的精准性。由此需扩大治疗体积以涵盖靶区不确定性，导致周围正常组织受量增加，从而限制了放疗剂量。借助影像引导放疗（IGRT），可优化这些体积并实施肿瘤致死剂量，实现最大肿瘤控制与最小并发症。此外，凭借高精度剂量输送和对靶区位置的实时掌握，IGRT 已开启对放疗新适应证的探索，其中一些此前被视为不可行。

原文链接：

Innovations in image-guided radiotherapy