Instrumentation for microSPECT and microPET imaging

国家癌症研究所的分子成像计划（MIP）负责开发与癌症的发展，生长和治疗相关的特定途径的化学探针。放射性核素标记的化合物是此类试剂的重要子集。成功开发的放射性核素标记的化合物提供了用于医学诊断和管理目的的人体受试者的PET、SPECT和平面成像的最终前景，以及当用于小型实验室动物的探针验证时在基础科学中的同样强大的应用。MIP放射性核素仪器组通过探索和实施改进或推进MIP小动物成像状态的新放射性核素成像技术来支持这一基础科学使命。由RIG及其（基本）合作者开展的开发工作基于定向探索的概念，其中技术机会在研究层面上进行检查（面板A，图1），但考虑到特定的系统级目标（面板B，图1）。 图1. (A)：成像系统开发研究领域：（B）：当前重点系统级开发项目：双伽马照相机平面投影成像系统，用于小鼠单光子、高速动态全身生物分布研究。为了说明这种并行性，RIG正在图1A所示的每个领域开展工作：LaBr 3板和NaI（Tl）像素化探测器模块和支持电子开发（CIT-NIH/RIG）;新的模块化数据采集系统的评估（托马斯杰斐逊国家加速器设施（JLAB），纽波特纽斯，VA/RIG）;使用质心事件定位和先进的最大似然（ML）定位（RIG/CIT）创建高速数据处理接口;和评价用于图像显示和分析的商业系统（Nuclear Mac）（RIG/CIT）。这些子系统项目中的每一个都是根据当前系统级目标进行评估的，该目标是创建一个用于成像小鼠的双平面伽马相机设备，同时提供每个技术领域的信息，以便在我们的下一个系统级开发项目中使用。例如，其中一个探测器模块（图1B中的M1或M2）将由一个矩形像素化NaI（Tl）阵列组成，该阵列与两个并排的Hamamatsu H8500位置敏感光电倍增管（PSPMT，面板A，图2）耦合。使用该组合获得的初始成像结果（图2的面板B）需要充分使用JLAB DAQ、CIT开发的电子设备和RIG开发的数据处理软件来采集和分析这些数据。 图2. (A)：NaI（Tl）探测器模块和支持电子设备（CIT/RIG）;（B）：来自该19 x 42（43 mm x 94 mm）像素模块的早期511 keV场泛光图像。注意两个并排PSPMT之间的差距中2 mm x 2 mm像素的清晰标识。一个定制的准直器已被设计为这个阵列，每个像素有自己的个人准直器孔。 我们计划继续这项探索性工作，目标是将完成的双伽马相机系统交给MIP科学家，然后审查累积的技术发现并指定下一个系统级项目。

The Molecular Imaging Program (MIP) of the National Cancer Institute is charged with the task of developing chemical probes specific to pathways associated with the development, growth and treatment of cancer. Radionuclide-labeled compounds are an important subset of such agents. Successfully developed radionuclide-labeled compounds offer the ultimate prospect of PET, SPECT and planar imaging in human subjects for medical diagnostic and management purposes, and equally powerful applications in basic science when used for probe validation in small laboratory animals. The MIP radionuclide instrumentation group supports this basic science mission by exploring and implementing new radionuclide imaging technologies that improve or advance the state of MIP small animal imaging. Development work carried out by the RIG and its (essential) collaborators is based on the notion of directed exploration where technological opportunities are examined at the research level (panel A, Figure 1) but with a particular systems level goal in mind (panel B, Figure 1). Figure 1. (A): Research areas in imaging system development: (B): current focused systems level development project: dual gamma camera planar projection imaging system for single photon, high-speed dynamic whole body bio-distribution studies in mice. To illustrate this parallelism, work is now underway in the RIG in each of the areas shown in Figure 1A: LaBr3 slab and NaI(Tl) pixelated detector modules and support electronics development (CIT-NIH/RIG); evaluation of a new, modular DAQ system (Thomas Jefferson National Accelerator Facility (JLAB), Newport News, VA/RIG); creation of a high speed data processing interface using both centroid event positioning and advanced Maximum Likelihood (ML) positioning (RIG/CIT); and evaluation of a commercial system (Nuclear Mac) for image display and analysis (RIG/CIT). Each of these sub-system projects are evaluated in light of the current systems level goal of creating a dual planar gamma camera device for imaging mice while at the same time providing information in each technical area for potential use in our next systems level development project. For example, one of the detector modules (M1 or M2 in Figure 1B) will be comprised of a rectangular pixelated NaI(Tl) array coupled to two side-by-side Hamamatsu H8500 position-sensitive photomultiplier tubes (PSPMTs, panel A, Figure2). Initial imaging results obtained with this combination (panel B, Figure 2) required full use of the JLAB DAQ, CIT developed electronics and RIG-developed data processing software for acquisition and analysis of these data. Figure 2. (A): NaI(Tl) detector module and supporting electronics (CIT/RIG); (B): early 511 keV field flood image from this 19 x 42 (43mm x 94 mm) pixel module. Note clear identification of the 2 mm x 2 mm pixels in the gap between the two side-by-side PSPMTs. A custom collimator has been designed for this array where each pixel has its own individual collimator hole. We plan to continue this exploratory work with the goal of turning over the completed dual gamma camera system to MIP scientists , followed by a review of accrued technical findings and designation of the next systems level project.