Quantitative SPECT with Medium-Energy Radionuclides

描述（由申请人提供）： 拟议的研究的长期目标是提高收购，重建和提取定量信息的SPECT图像的中等能量放射性核素，并评估这些改进的成像系统使用任务相关的标准。中能放射性核素对于癌症的诊断、分期和治疗变得越来越重要。在第一个项目期间，我们把注意力集中在改善准直和校正的散射和不均匀衰减的Ga-67 SPECT成像，以及提高我们的技术蒙特卡罗模拟中等能量的光子。在此更新申请中，我们将注意力转向其他中等能量放射性核素（如In-111，Lu-177和Cu-67）的SPECT成像的类似改进，这些核素在癌症诊断和治疗中发挥着越来越重要的作用。我们将建造和评估在上一个资助期内为Ga-67设计的新准直器，并设计、建造和评估In-111的新准直器。我们的经验，同时双同位素SPECT成像将扩展到放射性核素对，包括中等能量的光子发射器。我们将开发一种新的联合迭代算法，非常快速的蒙特卡罗模拟的基础上的散射，串扰，并导致X射线在几个能量窗口，同时纠正这些现象的SPECT图像的同位素发射多个衰变光子，以及完成同时成像的双同位素对。我们将使用模拟数据以及体模和患者数据来测量由于改进的成像程序而导致的活动和尺寸估计的改进，并将所实现的性能与理论界限进行比较。我们还将比较几种γ/β发射核素（或核素对）的实用性的基础上，可以完成放射免疫治疗剂量测定的准确性。我们的同时双同位素程序的可行性将进行评估的基础上，在两个临床任务的性能，使用患者的图像。第一个是使用Ga-67和TI-201的同时成像预测从低级到高级NHL的进展，第二个是基于Ga-67和Tc-99 m-MDP的同时成像诊断脊椎骨髓炎。我们预计，在拟议项目期间完成的成像系统改进将导致更准确的诊断、分期和/或患者治疗，从而改善患者护理。

DESCRIPTION (provided by applicant): The long-term goals of the proposed research are to improve the acquisition, reconstruction, and extraction of quantitative information from SPECT images of medium-energy radionuclides, and to assess these improvements to the imaging system using task-dependent criteria. Medium-energy radionuclides are becoming increasingly important for the diagnosis, staging, and treatment of cancer. During the first project period, we focused our attention on improving collimation and corrections for scatter and nonuniform attenuation for Ga-67 SPECT imaging, as well as on enhancing our techniques for Monte Carlo simulation of medium-energy photons. In this renewal application, we turn our attention to similar improvements to SPECT imaging of other medium-energy radionuclides, such as In-111, Lu-177, and Cu-67, that are playing an increasing role in cancer diagnosis and therapy. We will construct and evaluate new collimators, designed for Ga-67 during the previous funding period, and design, construct, and evaluate new collimation for In-111. Our experience in simultaneous dual-isotope SPECT imaging will be extended to radionuclide pairs that include medium-energy photon emitters. We will develop a new joint iterative algorithm, based on very rapid Monte Carlo simulation of scatter, crosstalk, and lead x-rays in several energy windows, to correct simultaneously for these phenomena on SPECT images of isotopes emitting multiple decay photons, as well as to accomplish simultaneous imaging of dual-isotope pairs. We will measure, using simulated data, as well as phantom and patient data, the improvements in activity and size estimation due to improved imaging procedures, and compare the performance achieved to theoretical bounds. We will also compare the utility of several gamma/beta-emitting nuclides (or nuclide pairs) on the basis of the accuracy with which radioimmunotherapy dosimetry can be accomplished. The feasibility of our simultaneous dual-isotope procedures will be evaluated on the basis of performance in two clinical tasks using patient images. The first is prediction of progression from low-grade to higher-grade NHL using simultaneous imaging of Ga-67 and TI-201, and the second is diagnosis of vertebral osteomyelitis based on simultaneous imaging of Ga-67 and Tc-99m-MDP. We expect that the imaging system improvements that will be accomplished during the proposed project period will lead to more accurate diagnosis, staging, and/or treatment of patients and, consequently, improved patient care.