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，可用作核医学应用的直接伽玛射线探测器，特别是正电子发射断层扫描(PET)。它有可能提供非常高的探测效率、优异的空间分辨率、低噪声和高能量分辨率。TlBr具有高Z组分、高密度、宽禁带半导体，基于材料提纯和生长的最新进展，可以在良好的电子电荷输运参数下制备。在室温下工作的小型半导体探测器具有高空间分辨率、高探测效率和良好的能量分辨率，与LSO、BGO和CdTe/CZT相比具有独特的优势，这些材料是小动物PET应用中最常见的g-射线探测器材料。事实上，在511keV时，TlBR的阻挡能力比目前用于PET扫描仪的任何其他材料都要好。高性能的PET探测器模块可以用来建立一种扫描仪，能够对小鼠大脑内的亚结构进行成像，或者对小鼠癌症模型中的肿瘤异质性和微环境进行定量评估。我们相信，这项将开发世界上第一个基于TlBr的PET探测器模块的提案将能够将这项前景光明的技术带到一个可以进行商业开发的地步。这项计划的目标是开发两个高灵敏度的TlBr探测器模块和相关的电子设备，其本征空间定位在两个维度上为0.5 mm，第三个维度为2.5 mm (深度)尺寸。具体目标是解决从现有的高质量检测器级TlBr钢锭中生产检测器模块所需的步骤，这些钢锭是通过流动熔融区方法生长的。这些钢锭足够大(直径分别为30 mm和50 mm)以切割基板，由此可以制造单片20 mm x 20 mm探测器。我们将：(1)优化平面探测器制造的材料工艺；(2)生产和测试单个交叉条探测器；(3)实现多路多路读出并表征该配置下的探测器性能；(4)构建两个堆叠探测器模块，并将其用于台式系统以评估PET成像性能。结合实验测量的探测器数据的蒙特卡罗模拟也将用于预测基于这些TlBr探测器模块的完整小动物PET扫描仪的性能。这些目标将在工艺和设计方面提供必要的开发，以生产有用的大面积和高性能探测器模块，最初的目标是提供小型动物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.