Quantitative SPECT with Medium-Energy Radionuclides

描述(由申请人提供)： 拟议研究的长期目标是改进从中能放射性核素SPECT图像中获取、重建和提取定量信息，并使用任务相关标准评估这些改进对成像系统的影响。中能放射性核素在癌症的诊断、分期和治疗中正变得越来越重要。在第一个项目期间，我们专注于改进对Ga-67 SPECT成像的散射和非均匀衰减的准直和校正，以及加强我们对中能光子的蒙特卡罗模拟技术。在这一新的应用中，我们将注意力转向其他中能放射性核素的SPECT成像的类似改进，如In-111、Lu-177和Cu-67，这些核素在癌症诊断和治疗中发挥着越来越大的作用。我们将建造和评估新的准直器，在上一个资金时期为Ga-67设计，并为In-111设计、建造和评估新的准直器。我们在同步双同位素SPECT成像方面的经验将扩展到包括中能光子发射体在内的放射性核素对。我们将开发一种新的联合迭代算法，基于对多个能量窗口中的散射、串扰和铅X射线的非常快速的蒙特卡罗模拟，以在发射多个衰变光子的同位素SPECT图像上同时校正这些现象，并完成双同位素对的同时成像。我们将使用模拟数据，以及体模和患者数据，测量由于改进的成像程序在活动和大小估计方面的改进，并将所取得的性能与理论界限进行比较。我们还将根据完成放射免疫治疗剂量测定的准确性来比较几种伽马/贝塔发射核素(或核素对)的效用。我们同时进行双同位素手术的可行性将根据患者在两项临床任务中的表现进行评估。第一种是利用Ga-67和TI-201的同时成像来预测从低度恶性到高度恶性的NHL的进展，第二种是基于Ga-67和99m-MDP的同时成像来诊断椎体骨髓炎。我们预计，在拟议的项目期间将完成的成像系统改进将导致对患者进行更准确的诊断、分期和/或治疗，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.