Road of PET Image-Based On-line Proton Beam Range Measurement

描述(申请人提供)：质子疗法(PT)是一种最新的最先进的放射疗法，可以将高水平的辐射聚焦到一个小目标。原则上，这种独特的物理特性将使PT成为一种靶向治疗，显著提高治疗效果，同时减少对正常组织的剂量，从而减少治疗并发症。然而，PT存在固有的物理不确定性，如果大剂量没有准确地输送，PT可能会对患者造成伤害。临床医生被迫采取过于保守的治疗方法，限制肿瘤的剂量，以确保保留正常组织。克服这一障碍对于显著提高PT的治疗效果和实现充分的临床益处至关重要。本研究项目旨在研究一种创新的基于PET图像的PT治疗方案在线验证的可行性，以取代目前的离线验证方法。从概念上讲，在线方法将在治疗开始前直接测量实际设置和射束范围(BEAM将停止的位置)与治疗计划的潜在偏差，这将最有效地提高PT的靶向精度，显著提高PT的治疗效果。然而，从技术上讲，实现在线测量是具有挑战性的，因为有两个主要的技术问题没有得到认真的研究：PET能否在这样的质子辐射环境中表现良好？计数统计大大降低的在线测量能否提供与离线测量相同的测量准确度和精密度？本项目试图通过追求三个具体目标来回答这些关键问题：放大现有的PET原型以进行在线成像可行性研究；在不同的质子辐射和PET成像条件下进行体模实验研究，以评估在线测量的可行性和PET的性能；调查在临床相关的辐射和成像条件下实现在线测量的技术要求。这项研究的结果有望为在线测量的可行性提供重要信息，获得其在高影响临床应用的潜力的前景，并有助于未来的技术开发。

DESCRIPTION (provided by applicant): Proton therapy (PT) is a latest state-of-art radiation therapy that can focus high level radiations to a small target. In principle, this unique physical property will allow PT to become a targeted therapy for significantly improved therapy efficacy while simultaneously reduced dose to normal tissues and thus reduced treatment complications. However, there are inherent physical uncertainties with PT which could make PT be harmful to a patient if the high dose were not delivered accurately. Clinicians have been forced to take overly conservative treatment approaches in restricting doses to the tumor in order to ensure sparing of normal tissues. It is critically important to overcome this impediment in order to dramatically enhance PT therapeutic outcomes and achieve the full clinical benefits. This research project aims to study the feasibility of an innovative PET image-based on-line verification of PT treatment plan instead of current off-line method. Conceptually, on-line approach will directly measure the potential deviation of actual setup and beam range (where beam will stop) from the treatment plan before the start of treatment, which will most effectively improve the targeting accuracy of PT and significantly enhance the PT therapy efficacy. Nevertheless, technically, it is challenging to achieve on-line measurement with two major technical questions have not been seriously investigated: Can a PET perform well in such proton radiation environment? Can on-line measurement with substantially lower count statistics provide the same level of measurement accuracy and precision as off-line measurement provides? This project attempts to answer these critical questions by pursuing three specific aims: scaling up an existing prototype PET to enable on-line imaging feasibility study; conducting phantom experimental studies under different proton radiation and PET imaging conditions to assess the feasibility of on-line measurement and PET performance; investigating the technical requirement to achieve on-line measurement under clinically relevant radiation and imaging conditions. The outcome of this research is expected to provide vital information on the feasibility of on-line measurement, gain the perspective of its potential for a high impact clinica application, and assist future technology development.