TlBr Detectors for High Resolution PET Imaging

描述（由申请人提供）：溴化铊（TlBr）是一种很有前途的半导体，可用作核医学应用，特别是正电子发射断层扫描（PET）的直接g射线探测器。它具有提供非常高的检测效率、优异的空间分辨率、低噪声和高能量分辨率的潜力。TlBr具有高Z组分、高密度、宽半导体带隙，并且基于材料纯化和生长的最新进展，可以产生具有良好的电子电荷传输参数的TlBr。在室温下工作的具有高空间分辨率、高检测效率和良好能量分辨率的紧凑型半导体检测器将提供优于LSO、BGO和CdTe/CZT的独特优势，LSO、BGO和CdTe/CZT是小动物PET应用中最常见的g射线检测器材料。事实上，TlBr在511 keV处具有比目前用于PET扫描仪的任何其他材料更好的阻止能力。高性能PET探测器模块可用于构建能够对小鼠大脑内的子结构进行成像的扫描仪，或定量评估小鼠癌症模型中的肿瘤异质性和微环境。我们相信，这一提案将开发世界上第一个基于TlBr的PET探测器模块，将能够使这一有前途的技术达到商业开发的程度。该提案的目标是开发两个高灵敏度TlBr探测器模块和相关电子器件，其内在空间定位在二维中为0.5 mm，在三维中为2.5 mm （深度）维度。具体目标解决了从通过移动熔融区法生长的现有高质量探测器级TlBr锭生产探测器模块所需的步骤。晶锭足够大（30 mm和50 mm直径）以切割衬底，由此可以制造单片20 mm x 20 mm检测器。我们将：（1）优化平面探测器制造的材料处理;（2）生产和测试单个交叉条带探测器;（3）实现多路复用多通道读出并表征该配置中的探测器性能;（4）构建两个堆叠探测器模块并将其用于台式系统中以评估PET成像性能。蒙特卡罗模拟，结合实验测量的探测器数据，也将被用来预测完整的小动物PET扫描仪的性能的基础上，这些TlBr探测器模块。这些目标将在工艺和设计方面提供必要的发展，以生产由TlBr制成的有用的大面积和高性能探测器模块，最初旨在提供小动物PET应用所需的亚毫米空间分辨率和高探测效率。

DESCRIPTION (provided by applicant): Thallium bromide (TlBr) is a promising semiconductor for use as a direct g-ray detector for nuclear medicine applications, especially for positron emission tomography (PET). It has the potential to provide very high detection efficiency, excellent spatial resolution, low noise and high-energy resolution. TlBr has high-Z constituents, high density, a wide semiconducting bandgap, and based on recent progress with material purification and growth, can be produced with good charge transport parameters for electrons. A compact semiconductor detector operating at room temperature with high spatial resolution, high detection efficiency and good energy resolution would offer unique advantages over LSO, BGO, and CdTe/CZT, which are the most common g-ray detector materials in small animal PET applications. Indeed, TlBr has better stopping power at 511 keV than any other material currently used in PET scanners. High performance PET detector modules could be utilized to build a scanner able to image substructures within the mouse brain, or to quantitatively assess tumor heterogeneity and microenvironment in a mouse cancer model. We believe that this proposal, which will develop the world's first TlBr-based PET detector modules, will be able to bring this promising technology to a point where its commercial exploitation will be possible. The goal of this proposal is to develop two high-sensitivity TlBr detector modules and associated electronics with intrinsic spatial localization of 0.5 mm in two dimensions and 2.5 mm in the third (depth) dimension. The specific aims address steps needed to produce detector modules from existing high quality detector grade TlBr ingots grown by the travelling molten zone method. The ingots are large enough (30 mm and 50 mm diameter) to cut substrates from which monolithic 20 mm x 20 mm detectors can be fabricated. We will: (1) optimize material processing for planar detector fabrication; (2) produce and test single cross-strip detectors; (3) implement multiplexed multi-channel readout and characterize detector performance in that configuration; (4) build two modules of stacked detectors and use them in a benchtop system to evaluate PET imaging performance. Monte Carlo simulations, incorporating experimentally-measured detector data, will also be used to predict the performance of complete small-animal PET scanners based on these TlBr detector modules. These aims will provide the necessary developments in process and design to produce usefully large-area and high-performance detector modules made from TlBr, aimed initially at providing the sub-mm spatial resolution and high detection efficiency needed for small-animal PET applications.