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: 9126689
• 负责人: Rose Schmitt Perea
• 金额: $ 2.82万
• 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/9126689
• 关键词: Algorithms; Animals; Area; Biological; CdZnTe; Charge; Compton radiation; Contrast Sensitivity; Data; Data Set; Detection; Digital Libraries; Discipline of Nuclear Medicine; Electronics; Estimation Techniques; Evaluation; Event; Gamma Cameras; Germanium; Goals; Head; Heart Diseases; Image; Imaging Techniques; Individual; Knowledge; Laboratories; Lead; Lesion; Maps; Measures; Mental disorders; Methods; Morphologic artifacts; Myocardial perfusion; Neurodegenerative Disorders; Noise; Performance; Photons; Positioning Attribute; Process; Property; Pulmonary Embolism; Research Training; Resolution; Scheme; Scientist; Semiconductors; Shapes; Side; Signal Transduction; Source; System; Techniques; Tomography, Computed, Scanners; Width; animal imaging; cancer type; contrast imaging; detector; 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，可用于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，可研究一系列主题，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。我们目前正在建立一个双头SPECT系统，使用双面条，高纯度锗（DSS HPGe）探测器。HPGe提供的能量分辨率（在140 keV下FWHM < 1%）比传统的NaI伽马相机好一个数量级，并且其电荷传输特性使得空间分辨率与CdZnTe像素探测器相似，同时使用更少的读出电子通道。DSS配置允许子像素定位，然而，检测器内的诸如电荷共享、电荷损失和康普顿散射的多个条带效应可能导致事件被错误定位和/或未计数。这降低了检测效率和整体灵敏度，可能导致重建图像中的伪影。替代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/或仅研究小的探测器区域）校正这些影响。这项研究的目的是调查和实施以下后处理技术：波形分析，最大似然（ML）估计，并在整个检测器的电荷损失校正。这将在三个目标中完成：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。利用这些数据集（每种技术一个）和波束位置的知识，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方法而不进行附加的后处理）。将通过测量以下各项对每种技术进行评价：均匀性、能量和空间分辨率，以及投影图像的评价（空间分辨率、信噪比和对比度噪声比、调制传递函数等），目的3）使用新SPECT系统实施新的位置估计技术，并评价新重建图像与我们当前的后处理技术之间的差异。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。