IN VIVO RADIONUCLIDE QUANTITATION USING EMISSION CT

该项目的长期目标是提高 单光子发射计算机断层扫描（SPECT），用于体内成像 Tc-99 m和Tl-201放射性标记药物的分布，以及 改进源分布参数SPECT量化， 数量、活动和浓度。主要的假设是 该项目是SPECT可以提高定性和定量， 1)使用会聚束SPECT几何形状，即扇形束，锥形束， 光谱、空间变化或（对于有限的源尺寸）超高 分辨率针孔准直; 2）重建 使用先验源信息的策略， 源/采集因素，例如衰减、散射和几何 准直器响应。我们建议调查这一假设， 实现适合于三重照相机的会聚光束几何形状 SPECT系统和重建算法对采集进行建模 源和周围环境中的过程和伽马射线相互作用 衰减介质滤波反投影（FBP）被广泛使用，因为它 提供了快速计算速度的实际优势;然而， 最大似然-期望最大化（ML-EM）和贝叶斯 采用任意采集几何形状（锥形束、双光束和 空间变化的准直）可以适当地在 重建算法贝叶斯重建方法可以 整体地包括先验源分布信息。用于SPECT 心脏成像，心脏壁运动的影响也将是 研究了这些采集几何结构和算法将是 定性和定量评价使用蒙特卡罗模拟 和拟人幻影的实验扫描，并与病人和 动物研究。为了实现我们的科学目标，我们建议 具体目标如下： A. SPECT心脏成像。实施和评估3D FBP、约束ML-EM 平行光束和会聚光束的三维贝叶斯重建算法 心脏的SPECT成像。算法会考虑到 几何系统响应、非均匀衰减和散射。一个新 空间变化聚焦准直器将被设计，建造， 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 大脑成像。算法会考虑到 几何系统响应、衰减和散射。一种新型 将设计、建造和评估会聚束准直器。 C. SPECT针孔成像。开发和评估小视场， 毫米分辨率针孔SPECT系统。 迭代和FBP算法 单针孔和多针孔SPECT将实施和评价。 将设计用于三相机SPECT系统的针孔准直器， 建立和评估。

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.