High-Performance Positron Emission Tomography for brain imaging

摘要 人脑仍然是科学中的谜团之一，许多脑部疾病和障碍，如 阿尔茨海默病给个人、家庭和社会留下了巨大的负担。神经退行性变 疾病的特征是神经元的进行性丧失，导致痴呆。最流行的形式 老年痴呆症是阿尔茨海默病(AD)。预计阿尔茨海默病患者人数将达到1400万 到2050年。虽然今天美国有数以千计的PET扫描仪，但没有设计或 针对大脑成像进行了优化。这些PET扫描仪是全身系统，通常有探测器空间 分辨率为4-6 mm半高宽；然而，该分辨率不足以成像具有精细结构的大脑，即 需要研究阿尔茨海默氏症或其他神经疾病。只有很少的PET系统 致力于商业上可用的或正在FDA批准过程中的脑成像。然而，一个也没有 它们的空间分辨率均优于2 mm FHWM，且均低于最佳吸收效率 对于511keV的伽马射线。本项目的主要目标是开发一种新型的高分辨率和高分辨率的光学系统。 灵敏的PET系统致力于脑成像。主要的创新是一个新的探测器概念，它是 灵活的交互深度和可提供高横向分辨率的单面读出 也是。我们将首先模拟设想的PET系统，并比较其在使用 将GFAG晶体与主流的Lyso闪烁体进行了比较。接下来，我们将通过优化 对GFAG闪烁体进行横向和DOI位置解码以获得1.2 mm的本征探测器分辨率 半高宽和至少4级DOI，单面SiPM读数。我们计划使用以下工具构建一个原型系统 两个完全特征化的探测器模块，并执行基本的体模成像。由于紧凑，成本- 我们建议的PET扫描仪高效、移动的设计，以及其卓越的性能，我们相信 该系统的成功开发可能会对我们对大脑的理解产生革命性的影响 以及包括阿尔茨海默病在内的神经退行性疾病。

Abstract Human brain is still one of the mysteries in science and many brain disease and disorders such as Alzheimer's disease have left a huge burden on individuals, their family, and the society. Neurodegenerative disease is characterized by a progressive loss of neurons that lead to dementia. The most prevalent form of dementia in elderly is Alzheimer disease (AD). The number of people with AD is expected to reach 14 million by year 2050. While there are thousands of PET scanners in the States today, there are not designed or optimized for brain imaging. These PET scanners are whole-body systems that typically have detector spatial resolution of 4-6 mm FWHM; however this resolution is not sufficient to image brain with fine structures that is required to study the Alzheimer's disease or other neurological disorders. There are only few PET systems dedicated to brain imaging that are commercially available or in the process of FDA approval. However, none of them provides better than 2mm FHWM spatial resolution and all have less than optimal absorption efficiency for the 511 keV gamma rays. The main objective of this project is to develop a novel high-resolution and high- sensitivity PET system dedicated to brain imaging. The main innovation is a novel detector concept which is flexible with depth of interaction capability and single-side readout that can provide high transverse resolution as well. We will first simulate the envisaged PET system and compare its expected performance when using GFAG crystals compared to the mainstream LYSO scintillators. We will follow by optimizing both the transverse and DOI position decoding of GFAG scintillators to achieve intrinsic detector resolution of 1.2 mm FWHM and at least 4 levels of DOIs with single-side SiPM readout. We plan to build a prototype system using two fully characterized detector modules and perform basic phantom imaging. Owing to the compact, cost- effective, and mobile design of our proposed PET scanner together with its superior performance, we believe successful development of the system will likely have a transformational impact on our understanding of brain and neurodegenerative diseases including the AD.