Development of magnetic resonance image guided radiotherapy

放射治疗(RT)仍然是治疗原发癌和转移癌的有效方法。现代治疗方法是在影像引导下进行放射治疗。这使得能够更好地控制剂量放置，允许剂量递增到肿瘤，同时减少附近有风险的器官的副作用。目前的护理标准是一套单一的计划扫描，然后是几周的RT。在放射肿瘤学中，磁共振成像(MRI)被用来获得精细的非侵入性软组织图像。然而，计划和治疗之间的基本不确定性、治疗过程中的运动以及几周内肿瘤大小不可避免的变化最终限制了RT的精确度和准确性。可能会出现正常组织的过度治疗或肿瘤剂量不足，这可能会损害患者的生活质量和生存。本提案描述了一个广泛的研究计划，在该计划中，我们将开发必要的新型MRI技术来指导和适应RT交付。我们的目标是使用最近开发的名为MRI-LINAC的先进图像引导RT平台来实现这一点，该平台集成了外部束流直线加速器和诊断性1.5T磁共振扫描仪。这两项技术的结合是协同的：治疗过程中的成像(称为“束上”)能够实现自适应肿瘤跟踪，而治疗后成像功能使医生能够快速评估治疗反应。我们的短期目标是(1)开发用于自适应RT的实时束上成像，(2)优化仅限MR的治疗模拟，(3)在体内，基于MR的剂量学的进展，以及(4)整合用于治疗反应监测的分子成像。这些流的结合旨在提高MRI在放射肿瘤学中的价值，在规划、交付和反应评估的不同领域。从长远来看，可视化肿瘤及其反应的能力将彻底改变放射治疗在临床上的应用方式，但使其成为现实的技术进步尚未开发出来。这项工作的目的是开发MR引导的放射治疗的基本技术，为最终的临床应用奠定基础。这些技术跨越了从脉冲序列到硬件的整个磁共振技术范围，预计不仅在肿瘤学中具有广泛的影响，而且在诊断和介入放射学中也具有广泛的影响。我们还预计，我们计划的硬件开发方面将带来巨大的商业潜力。

Radiotherapy (RT) remains an effective treatment for both primary and metastatic cancers. Modern treatments deliver radiation under image guidance. This enables better control on dose placement, allowing dose escalation to tumours whilst reducing side effects in nearby organs at risk. The current standard of care is a single set of planning scans, followed by several weeks of RT.In radiation oncology, magnetic resonance imaging (MRI) is used to obtain exquisite non-invasive images of soft tissues. However, fundamental uncertainties inaccuracies between planning and treatment, motion during the treatment itself, and inevitable changes in tumour size over several weeks ultimately limit RT precision and accuracy. Potential overtreatment of normal tissue or under-dosing of tumour are possible, which can harm patient quality of life and survival.This proposal describes a broad research program in which we will develop the novel MRI technologies necessary to guide and adapt RT delivery. We aim to do this using a recently developed advanced image-guided RT platform called the MRI-LINAC, which integrates an external beam linear accelerator with a diagnostic 1.5T MRI scanner. The combination of these two technologies is synergistic: imaging during treatment (referred to as “beam-on”) enables adaptive tumour tracking, and the ability to treat and then image function allows the doctor to quickly assess response to treatment.Our short term objectives are (1) development of real-time beam-on imaging for adaptive RT, (2) optimization of MR-only treatment simulation, (3) advances for in vivo, MR-based dosimetry, and (4) integration of molecular imaging for treatment response monitoring. The combination of these streams aims to improve the value of MRI in radiation oncology, in the diverse areas of planning, delivery, and response assessment. In the long run, the ability to visualize tumours and their response will revolutionize the way in which RT is clinically used, but the technical advances to make this a reality have not yet been developed.The aim of this work is to develop the fundamental techniques in MR-guided RT which underlie eventual clinical applications. These techniques span the entire range of MR technology from pulse sequences to hardware, and are anticipated to have wide-ranging implications not only within oncology, but also within both diagnostic as well as interventional radiology. We also anticipate significant commercial potential arising from hardware development aspects of our program.