OPTIma: Optimising Proton Therapy through Imaging

英国每年诊断出超过35万例癌症病例，其中约40%的患者接受放射治疗作为其治愈性治疗的一部分。大多数放射治疗采用由直线加速器产生的外部x射线束。然而，人们对使用高能质子束进行放射治疗越来越感兴趣。在英国，两个NHS中心和几个私人中心将在未来几年内开放。质子束治疗对头颈部肿瘤、某些脑肿瘤、危险器官附近的肿瘤和儿童癌症最有用。质子以与X射线（光子）非常不同的方式失去能量，因为它们在组织中具有有限的范围，其大部分能量沉积在该范围的末端附近。因此质子可以以集中的剂量靶向肿瘤，而健康组织受到的辐射较少。显然，挑战在于准确预测质子将存款其大部分能量的位置--在靶肿瘤中，而不是在邻近的健康组织中。治疗计划目前基于X射线CT图像，但这在从基于低能X射线的图像转换到高能质子的范围时引起不可避免的不确定性。答案是使用相同的辐射类型进行治疗和成像-“相同规则”的概念。质子成像已被证明是困难的，因为当单个质子穿过患者或体模时，需要跟踪单个质子并记录每个质子的相应剩余能量。我们之前的项目PRaVDA为宽质子束奠定了基础。当前的质子束治疗设施使用在目标区域上电磁扫描的小直径束。这意味着一个完全不同的仪器概念和设计，但基于我们的经验与PRaVDA。该项目的理念是提供一个强大的、交钥匙的（尽可能是一个尖端仪器），可以被更广泛的社区利用。该项目将在曼彻斯特科视Christie质子束治疗中心的独特研究室提供一个国家设施，用于探索质子成像与最先进的扫描质子束传输系统。这将为研究界开辟一种新的医学成像模式-放射治疗中的带电粒子成像。项目的主要目标是：探索质子CT和X线摄影在将范围不确定性降低到不影响最佳治疗计划的水平方面的能力;开发复杂生物样本的算法，以计算高效的方式提供令人满意的可量化图像;结合质子CT和其他图像（X射线CT，PET等）的不同模式，以提供更多的临床信息和改进的图像;为其他质子治疗中心提供精确校准体模的设备和方法;了解质子CT如何成功地整合到从计划到治疗监测的治疗工作流程中。进一步开发用于机架系统的质子成像，并鼓励商业开发。

Over 350,000 cancer cases are diagnosed annually in the UK with some 40% of patients receiving radiotherapy as part of their curative treatment. Most radiotherapy treatments employ external x-ray beams generated by linacs. However, there is a growing interest in the use of high-energy proton beams for radiotherapy. Within the UK, two NHS centres and several private ones will open in the next few years. Proton Beam Therapy is most useful for tumours in the head/neck region, some brain tumours, tumours near to organs at risk and childhood cancers. Protons lose their energy in a very different way to x-rays (photons) as they have a finite range in tissue with most of their energy being deposited near the end of this range. So protons can target a tumour with a focused dose with less exposure of healthy tissue to radiation. The challenge is, clearly, predicting accurately where the protons will deposit the bulk of their energy - in the target tumour and not in neighbouring healthy tissue. Treatment planning is currently based on x-ray CT imagery but this gives rise to unavoidable uncertainties in translating from images based on low energy x-rays to the ranges of high energy protons. The answer is to use the same radiation type to treat and to image - the concept of the 'same ruler'. Imaging with protons has proved difficult as it is necessary to track individuals protons as they pass through a patient or phantom and record the corresponding residual energy of each proton. Our previous project, PRaVDA, laid the foundations of this for a broad beam of protons. Current Proton Beam Therapy facilities use small diameter beams that are electromagnetically scanned over the target region. This implies a radically different instrument concept and design, but based on our experience with PRaVDA. The philosophy is to provide a robust, turn-key (as far as feasible for a cutting-edge instrument) that can be exploited by a wider community.This project will provide a national facility in the unique Research Room at The Christie Proton Beam Therapy Centre, Manchester, for exploring proton imaging with a state-of-the-art scanning pencil-beam delivery system. This will open up to the research community a new medical imaging modality - charged-particle imaging in radiotherapy. The main project aims are:Explore the capabilities of proton CT and radiography in reducing range uncertainties to a level that do not influence optimum treatment planning.Develop algorithms for complex biological samples that provide in a computationally efficient manner satisfactory and quantifiable imagery.Combining different modes of proton CT and other imagery (x-ray CT, PET, etc) to provide more clinical information and improved imagery.Providing a facility and a methodology for the accurate calibration of phantoms for other proton therapy centres.Understanding how proton CT can be successfully integrated in treatment workflows from planning to in and between treatment monitoring. Further the development of proton imaging for gantry systems and encourage commercial exploitation.