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治疗的内在优势是能够选择性地沉积大量 主要肿瘤部位或感兴趣区域内的剂量，同时将对健康组织的剂量降至最低。充分地 利用这一优势，质子射程必须得到精确控制、监测和验证。中的小错误 微粒输送可导致大剂量输送到健康组织，更重要的是最小剂量 已发送到目标卷。然而，目前尚缺乏质子射程验证的临床解决方案。当前 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)的方法 利用电荷粒子径迹的二次发射的技术。启用了质子范围的PET 由于电荷粒子径迹中产生的正电子发射核的验证。不幸的是，放射性核素 对这项技术的兴趣可以有长达20分钟的半衰期，其中显著的生物清洗可以 发生，降低了湮没光子起源和原始质子径迹位置之间的相关性。PGI 为电荷粒子疗法的实时活体范围验证提供了最有希望的机会，如 这种方法中的二次排放是在很短的时间尺度(皮秒到毫秒)上产生的。 为了满足临床活体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成像系统原型 能量伽马射线与像素化闪烁探测器读数相结合。这个原型提供了两个- 使用这个准直器对PGI轨迹进行三维成像。50 MeV质子成像仪的初步评价 射束通过其迅速的伽马发射显示出非凡的希望来对质子轨迹进行成像，包括亚 质子射程量化的精度，其质子统计数据与 心理治疗。我们建议评估这个原型PGI系统的临床相关束流，束流， 以及在临床环境中展示其性能能力的场景。来自这些评估的数据将 充分表征原型系统的功能，突出临床应用，并指导设计 先进的临床成像系统，可在小型模块化平台中进行实时活体质子射程验证 可放置在患者和机架周围，适用于任何治疗方案。

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.