High quality radiation therapy requires highly accurate and precise dose delivery. MR-guided radiotherapy (MRgRT), integrating an MRI scanner with a linear accelerator, offers excellent quality images in the treatment room without subjecting patient to ionizing radiation. MRgRT therefore provides a powerful tool for intrafraction motion management. This paper summarizes different sources of intrafraction motion for different disease sites and describes the MR imaging techniques available to visualize and quantify intrafraction motion. It provides an overview of MR guided motion management strategies and of the current technical capabilities of the commercially available MRgRT systems. It describes how these motion management capabilities are currently being used in clinical studies, protocols and provides a future outlook.

高质量的放射治疗需要高度准确和精确的剂量输送。 MR 引导放射治疗 (MRgRT) 将 MRI 扫描仪与直线加速器集成在一起，可在治疗室中提供高质量的图像，而无需使患者受到电离辐射。因此，MRgRT 为分次内运动管理提供了强大的工具。本文总结了不同疾病部位的分次内运动的不同来源，并描述了可用于可视化和量化分次内运动的 MR 成像技术。它概述了 MR 引导运动管理策略以及商用 MRgRT 系统的当前技术能力。它描述了这些运动管理功能目前如何在临床研究、协议中使用，并提供了未来的展望。