IN VIVO RADIONUCLIDE QUANTITATION USING EMISSION CT

该项目的长期目标是增强 单光子发射计算机断层扫描(SPECT)活体成像 ~(99)Tc和~(201)Tl-放射性标记药物的分布 改进源分布参数的SPECT量化，例如 体积、活动和浓度。这其中的主要假设是 项目是SPECT可以通过以下方式在质量和数量上得到改进 1)使用会聚束SPECT几何结构，即扇束、锥束， 像散、空间变化或(对于有限的震源大小)超高 分辨率针孔准直；以及2)实施重建 使用先验源信息并说明 源/采集因素，如衰减、散射和几何形状 准直器反应。我们建议通过以下方式来研究这一假设 实现适用于三摄像机的会聚光束几何 SPECT系统和对采集建模的重建算法 震源和周围环境内的过程和伽马射线相互作用 衰减介质。滤波反投影法(FBP)因其优点而得到了广泛的应用 提供了计算速度快的实际优势；然而，使用 最大似然-期望最大化(ML-EM)与贝叶斯 接近任意采集几何形状(锥形波束、像散和 空间变化的准直)可以在 重建算法。贝叶斯重建方法可以 包括先验源分布信息。用于SPECT 心脏成像，对心壁运动的影响也会 调查过了。这些采集几何图形和算法将是 蒙特卡罗模拟的定性和定量评价 和拟人化幻影的实验扫描，以及患者和 动物研究。为了实现我们的科学目标，我们建议 以下是具体目标： A.SPECT心脏成像。实施和评估3D FBP、约束ML-EM 平行束和会聚束的三维贝叶斯重建算法 心脏的SPECT成像。这些算法将考虑到 几何系统响应、非均匀衰减和散射。一种新的 空间变化的聚焦准直器将被设计、建造和 已评估。 B.SPECT脑成像。实施和评估3D FBP、约束ML-EM 会聚束SPECT的三维贝叶斯重建算法 大脑的成像。这些算法将考虑到 几何系统的响应、衰减和散射。一种新型的 会聚光束准直器将被设计、建造和评估。 C.SPECT针孔成像。开发和评估小视场， 毫米分辨率针孔SPECT系统。迭代算法和FBP算法 对于单针孔和多针孔，将实施和评估SPECT。 将设计用于三摄像机SPECT系统的针孔准直器， 构建和评估。

The long term goals of this project are to enhance the capabilities of single photon emission computed tomography (SPECT) to image in vivo distributions of Tc-99m- and Tl-201- radiolabeled pharmaceuticals, and to improve SPECT quantification of source distribution parameters such as volumes, activities and concentrations. The main hypothesis of this project is that SPECT can be improved qualitatively and quantitatively by 1) using converging beam SPECT geometries, i.e. fan beam, cone beam, astigmatic, spatially varying, or (for limited source sizes) ultra-high resolution pinhole collimation; and 2) implementing reconstruction strategies that use a priori source information and account for source/acquisition factors such as attenuation, scatter, and geometric collimator response. We propose to investigate this hypothesis by implementing converging beam geometries appropriate for a triple camera SPECT system and reconstruction algorithms that model the acquisition process and gamma ray interactions within the source and surrounding attenuating medium. Filtered backprojection (FBP) is widely used since it offers the practical advantage of fast computational speed; however, with Maximum Likelihood-Expectation Maximization (ML-EM) and Bayesian approaches arbitrary acquisition geometries (cone beam, astigmatic, and spatially varying collimation) can be implemented appropriately within the reconstruction algorithm. Bayesian reconstruction approaches can integrally include a priori source distribution information. For SPECT cardiac imaging, the effects of heart wall motion also will be investigated. These acquisition geometries and algorithms will be qualitatively and quantitatively evaluated using Monte Carlo simulations and experimental scans of anthropomorphic phantoms, and with patient and animal studies. To achieve our scientific objectives we propose the following specific aims: A. SPECT Cardiac Imaging. Implement and evaluate 3D FBP, constrained ML-EM and 3D Bayesian reconstruction algorithms for parallel and converging beam SPECT imaging of the heart. The algorithms will account for the effects of geometric system response, nonuniform attenuation and scatter. A new spatially varying focusing collimator will be designed, built, and evaluated. B. SPECT Brain Imaging. Implement and evaluate 3D FBP, constrained ML-EM and 3D Bayesian reconstruction algorithms for converging beam SPECT imaging of the brain. The algorithms will account for the effects of geometric system response, attenuation and scatter. A new type of converging beam collimator will be designed, built, and evaluated. C. SPECT Pinhole Imaging. Develop and evaluate small-field-of-view, millimeter-resolution pinhole SPECT system. Iterative and FBP algorithms for single and multiple pinhole SPECT will be implemented and evaluated. Pinhole collimators for a triple camera SPECT system will be designed, built and evaluated.