Clinical Imaging Performance Evaluation of a Multi-Knife-Edge Slit Collimator-based Prompt Gamma Ray Imaging System

项目摘要 质子治疗相对于传统放射疗法的内在优势是能够选择性地存款大的放射性粒子。 在原发性肿瘤部位或感兴趣区域内的剂量的量，同时最小化对健康组织的剂量。充分 利用这一优势，必须精确控制、监测和核实质子射程。中的小误差 颗粒递送可导致递送到健康组织的显著剂量 输送至目标体积。然而，缺乏用于质子范围验证的临床解决方案。电流 方法采用基于正电子发射断层扫描（PET）或基于即时伽马成像（PGI 技术，其利用来自带电粒子轨迹的二次发射。PET已启用质子范围 由于在带电粒子轨道中产生的正电子发射核，不幸的是， 对该技术感兴趣化合物的半衰期可长达20分钟，其中显著的生物清除可 发生，降低湮灭光子起源和原始质子轨道位置之间的相关性。PGI 为带电粒子治疗的实时体内范围验证提供了最有希望的机会， 这种方法中的二次发射在非常短的时间尺度（皮秒到毫秒）上产生。 为了满足临床体内范围验证系统的需求，劳伦斯伯克利国家实验室 （LBNL）开发了一种基于新型多刀口狭缝准直器的原型成像系统， 能量伽马射线与像素化闪烁检测器读出的组合。这个原型提供了两个- 使用该准直器对PGI轨迹进行三维成像。50MeV质子成像仪的初步评价 光束显示出特殊的承诺，成像质子轨道通过其即时伽马发射，包括亚， 质子范围定量的精确度为mm，质子统计与 疗法我们建议在临床相关射束能量、射束电流 和场景，以证明其在临床环境中的性能。这些评价的数据将 充分表征原型系统的功能，突出临床实用性，并指导设计 先进的临床成像系统，用于在小型模块化平台中进行实时体内质子范围验证， 可以定位在患者和机架周围，用于任何治疗方案。

Project Summary Proton therapy’s intrinsic advantage over conventional radiotherapy is the ability to selectively deposit large amounts of dose within a primary tumor site or region of interest while minimizing dose to healthy tissue. To fully leverage this advantage, proton range must be precisely controlled, monitored, and verified. Small errors in particle delivery can result in significant dose delivered to healthy tissue and more importantly minimal dose delivered to target volume. However, there is a lack of clinical solutions for proton range verification. Current approaches employ either positron emission tomography (PET)-based or prompt gamma imaging (PGI)-based techniques, which exploit the secondary emissions from charge particle tracks. PET is enabled for proton range verification due to positron emitting nuclei created in the charge particle tracks. Unfortunately, radionuclides of interest for this technique can have a half-life as long as 20 minutes, wherein significant biological washout can occur, degrading the correlation between annihilation photon origin and the original proton track location. PGI presents the most promising opportunity for real-time, in vivo range verification for charge particle therapies, as the secondary emissions in this approach are produced on very short time scales (picoseconds-to-milliseconds). To address the need for a clinical in vivo range verification system, Lawrence Berkeley National Laboratory (LBNL) has developed a prototype imaging system based on a novel multi-knife-edge slit collimator for high energy gamma-rays in combination with pixelated scintillation detector readout. This prototype provides two- dimensional imaging of PGI tracks using this collimator. Preliminary evaluations of the imager with 50 MeV proton beams showed exceptional promise for imaging proton tracks via their prompt gamma emissions, including sub- mm precision for proton range quantification with proton statistics commensurate to those present during therapy. We propose to evaluate this prototype PGI system in clinically relevant beam energies, beam currents, and scenarios to demonstrate its performance capabilities in a clinical setting. Data from these evaluations will fully characterize the prototype system’s capabilities, highlight clinical utility, and also guide the design of an advanced clinical imaging system for real-time, in vivo proton range verification in a small modular platform that can be positioned about the patient and gantry for any treatment regimen.