Proton Beam Therapy Dose Calculations and Evaluation using MRI

1)研究背景的简要描述，包括潜在的影响UCLH的质子束治疗(PBT)中心已经开始治疗患者。PBT是一种精确的放射治疗，在这种治疗中，高度集中的剂量可以输送到目标。与基于光子的放射治疗(RT)相比，PBT患者应该受益于周围健康组织的剂量减少；这使得PBT成为特别是辐射敏感区域的肿瘤的有利治疗选择，然而，准确和可靠的治疗计划对于实现PBT的好处至关重要。MRI在PBT中的进一步应用潜力明显。后续的MRI扫描提供了一个通过放射相关图像改变(RAIC)来回顾评估PBT治疗的机会。回顾治疗评估对PBT特别有用，因为在治疗过程中不能核实集中剂量的真实位置。在PBT中确定RAIC的特征将能够回顾评估治疗的准确性，并将有助于研究特定结构对辐射剂量的敏感性和反应。由于质子阻止能力受到电子密度的强烈影响，CT被用于治疗计划和剂量计算。CT也比MRI更有效，提供更好的几何精度，然而，CT扫描会给健康组织带来相当大的辐射剂量，因此患者风险更大。针对PBT的单纯MRI治疗计划已经被提出，以减少从CT到辐射敏感区健康组织的剂量。对于PBT，这项技术将利用MRI的组织分类潜力来产生更多关于质子阻止能力的信息地图。两种MRI用例PBT的可行性都受到常规MRI获得的强度和图像对比度的变异性的限制。为了实现仅使用MRI的治疗计划和评估，将需要改进和优化定量MRI技术。2)目的和目的MRI的益处在PBT中有明显的应用潜力。该项目旨在开发在PBT治疗过程中获得的MRI扫描，以改进治疗计划和评估。最初，这个项目将专注于儿童脑癌的治疗；大脑相对自由，神经成像社区有大量可用的软件用于图像配准、分割和校正。具体目标是：-研究图像处理技术和开发定量MRI序列以提高RAIC的可见性-回顾质子阻止能力的物理模型，以了解不同组织属性对剂量分布的影响。-通过后续MRI扫描将观察结果与PBT治疗计划的实际改进联系起来。-评估临床医生和患者仅使用MRI治疗计划的可行性和实用性。改进核磁共振序列和现有的生成质子阻止能力图的技术。3)研究方法的新颖性在这个项目中，将开发新的核磁共振序列用于PBT治疗的计划和评估。以前的研究已经对使用MRI的治疗计划和评估进行了初步调查，然而这些研究是基于常规的MRI序列，而这些序列并不是为这些目的而设计的。该项目将探索和优化定量MRI序列，以优化其用于PBT治疗计划和评估的能力。4)与EPSRC的战略和研究领域保持一致本项目与EPSRC的“医学成像--包括医学图像和视觉计算”研究领域保持一致。5)任何参与的公司或合作者该项目是与伦敦大学学院医院NHS基金会信托基金的NHS质子束治疗服务合作进行的。

1) Brief description of the context of the research including potential impactThe Proton Beam Therapy (PBT) centre at UCLH has started treating patients. PBT is a precise radiation treatment in which a highly concentrated dose can be delivered to the target. Compared to photon-based radiotherapy (RT), PBT patients should benefit from reduced dose to surrounding healthy tissue; this makes PBT a favourable treatment option for tumours in particularly radiosensitive regions, however, accurate and reliable treatment planning is critical for realising the benefits of PBT.There is clear potential for MRI to be further utilised in PBT. Follow up MRI scans present an opportunity to retrospectively evaluate PBT treatment through radiation associated image changes (RAICs). Retrospective treatment evaluation is especially useful for PBT since the true position of concentrated dose can't be verified during treatment. Characterising RAICs in PBT would enable retrospective evaluation of treatment accuracy and would facilitate investigations into the susceptibility and response of specific structures to radiation dose. CT is used for treatment planning and dose calculation since proton stopping power is strongly influenced by electron density. CT is also more efficient and offers better geometric accuracy than MRI, however, CT scans impart considerable radiation dose to healthy tissue so carry greater patient risk. MRI-only treatment planning for PBT has been proposed to reduce dose from CT to healthy tissues in radiosensitive regions. For PBT, this technique would utilise the tissue classification potential of MRI to produce more informed maps of proton stopping power. The feasibility of both MRI use cases PBT is limited by the variability of intensity and image contrast obtained through conventional MRI. To realize MRI-only treatment planning and evaluation, quantitative MRI techniques will need to be refined and optimised.2) Aims and ObjectivesThere is clear potential for the benefits of MRI to be further utilised in PBT. This project aims to develop the MRI scans acquired throughout PBT treatment to improve treatment planning and evaluation. Initially, this project will focus on paediatric brain cancer treatments; the brain is relatively motion-free and there is extensive available software from the neuroimaging community for image registration, segmentation, and correction. The specific objectives are to:- Investigate image processing techniques and develop quantitative MRI sequences to enhance visibility of RAICs- Review physical models of proton stopping power to understand the influence of different tissue properties on dose distribution.- Relate observations through follow-up MRI scans to practical improvements in PBT treatment planning.- Evaluate feasibility and practical utility of MRI-only treatment planning for clinicians and patients. Refine MRI sequences and existing techniques for generating maps of proton stopping power.3) Novelty of Research MethodologyIn this project, novel MRI sequences will be developed for PBT treatment planning and evaluation. Previous studies have performed preliminary investigations into treatment planning and evaluation using MRI, however these studies have been based on conventional MRI sequences which are not designed for these purposes. This project will explore and refine quantitative MRI sequences to optimise their capacity for PBT treatment planning and evaluation.4) Alignment to EPSRC's strategies and research areasThis project is aligned with EPSRC's 'Medical imaging - including medical image and vision computing' research area. 5) Any companies or collaborators involvedThis project is in collaboration with the NHS Proton Beam Therapy service at University College London Hospitals NHS Foundation Trust.