Mapping HPGe double-sided strip detector with x-rays for improved detector performance and position estimation

使用 X 射线映射 HPGe 双面条形探测器，以提高探测器性能和位置估计

• 批准号: 9353656
• 负责人: Rose Schmitt Perea
• 金额: $ 2.87万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9353656
• 关键词: Algorithms; Animals; Area; Biological; CdZnTe; Charge; Compton radiation; Data; Data Set; Detection; Digital Libraries; Dimensions; Discipline of Nuclear Medicine; Electronics; Estimation Techniques; Evaluation; Event; Gamma Cameras; Germanium; Goals; Heart Diseases; Image; Imaging Techniques; Individual; Injectable; Knowledge; Laboratories; Lesion; Maps; Measures; Mental disorders; Methods; Morphologic artifacts; Myocardial perfusion; Neurodegenerative Disorders; Noise; Performance; Photons; Positioning Attribute; Property; Pulmonary Embolism; Research Training; Resolution; Roentgen Rays; Scheme; Scientist; Semiconductors; Shapes; Side; Signal Transduction; Source; System; Techniques; Width; animal imaging; cancer type; contrast imaging; detector; high resolution imaging; improved; interest; public health relevance; radiotracer; response; signal processing; single photon emission computed tomography; tumor

 DESCRIPTION (provided by applicant): Single Photon Emission Computed Tomography (SPECT) is a nuclear medicine imaging technique that allows for the mapping of the biological distribution of an injected radiotracer; depending on the type of radiotracer a range of topics may be studied, such as: mental and neurodegenerative disorders, various types of cancers, pulmonary embolisms, and heart disease. We are currently building a dual-headed SPECT system that uses double-sided strip, high-purity germanium (DSS HPGe) detectors. HPGe offers an energy resolution (FWHM < 1% at 140 keV) an order of magnitude better than conventional NaI gamma cameras, and its charge transport properties enable spatial resolutions similar to that of CdZnTe pixel detectors while using far fewer channels of readout electronics. The DSS configuration allows for sub-pixel positioning, however, multiple strip effects such as charge sharing, charge loss and Compton scattering within the detector can cause the events to be mis- positioned and/or uncounted. This decreases detection efficiency and overall sensitivity, possibly leading to artifacts in the reconstructed image. Alternative, advanced post-processing techniques have been shown to correct for these effects in limited cases (specific detector configurations and/or only small detector areas investigated). The goal of this proposed study is to investigate and implement the following post-processing techniques: waveform analysis, Maximum-Likelihood (ML) estimation, and charge loss correction across the whole detector. This will be done in three aims: Aim 1) Carefully measure the detector system response using the Advanced Photon Source (APS) at Argonne National Laboratory, Aim 2) Perform the position estimation techniques on the data obtained in aim 1. With these data sets (one for each technique) and knowledge of the beam position the three-dimensional position of each event may be determined using the ML estimation (note that one technique is to try the ML method without additional post-processing). Each technique will be evaluated by measuring: uniformity, energy and spatial resolution, and evaluation of a projected image (spatial resolution, signal- and contrast-to-noise ratio, modulation transfer function, etc), and Aim 3) Implement the new position estimation technique with the new SPECT system and evaluate the differences between the new reconstructed image compared to our current post-processing technique. We expect to obtain reconstructed SPECT images that have higher resolution, sensitivity, and contrast, as well as fewer artifacts, leading to better detectability.

 描述（由申请人提供）：单光子发射计算机断层扫描（SPECT）是一种核医学成像技术，可以绘制注射放射性示踪剂的生物分布图；根据放射性示踪剂的类型，可以研究一系列主题，例如例如：精神和神经退行性疾病、各种类型的癌症、肺栓塞和心脏病。我们目前正在构建使用双面带、高纯度锗的双头 SPECT 系统。 (DSS HPGe) 探测器的能量分辨率（140 keV 时 FWHM < 1%）比传统 NaI 伽玛相机高一个数量级，其电荷传输特性可实现与 CdZnTe 像素探测器相似的空间分辨率，同时使用的数量少得多。 DSS 配置允许子像素定位，但是，探测器内的电荷共享、电荷损失和康普顿散射等多重条带效应可能会导致这些事件。错误定位和/或未计数这会降低检测效率和整体灵敏度，可能导致重建图像中出现伪影。替代性的先进后处理技术已被证明可以在有限的情况下（特定的探测器配置和）纠正这些影响。 /或仅研究小探测器区域）。这项研究的目标是研究和实施以下后处理技术：波形分析、最大似然（ML）估计和整个探测器的电荷损失校正。分三步完成目标： 目标 1) 使用阿贡国家实验室的高级光子源 (APS) 仔细测量探测器系统响应，目标 2) 对目标 1 中获得的数据执行位置估计技术。使用这些数据集（每种技术一个）和光束位置的知识可以使用 ML 估计来确定每个事件的三维位置（注意，一种技术是尝试 ML 方法，无需额外的后处理）每种技术将通过测量来评估：均匀性、能量。和空间分辨率，投影图像的评估（空间分辨率、信噪比、对比度、调制传递函数等），目标 3) 使用新的 SPECT 系统技术实现新的位置估计，并评估新重建的图像之间的差异与我们当前的后处理技术相比，我们期望获得具有更高分辨率、灵敏度和对比度以及更少伪影的重建 SPECT 图像，从而获得更好的可检测性。