Department of Nuclear, Plasma, and Radiological Engineering, The University of Illinois at Urbana Champaign, Urbana-Champaign, IL 61801, USA.
Phys Med Biol. 2013 May 7;58(9):3037-59. doi: 10.1088/0031-9155/58/9/3037. Epub 2013 Apr 15.
In this paper, we present an analytical approach for optimizing the design of a static SPECT system or optimizing the sampling strategy with a variable/adaptive SPECT imaging hardware against an arbitrarily given set of system parameters. This approach has three key aspects. First, it is designed to operate over a discretized system parameter space. Second, we have introduced an artificial concept of virtual detector as the basic building block of an imaging system. With a SPECT system described as a collection of the virtual detectors, one can convert the task of system optimization into a process of finding the optimum imaging time distribution (ITD) across all virtual detectors. Thirdly, the optimization problem (finding the optimum ITD) could be solved with a block-iterative approach or other nonlinear optimization algorithms. In essence, the resultant optimum ITD could provide a quantitative measure of the relative importance (or effectiveness) of the virtual detectors and help to identify the system configuration or sampling strategy that leads to an optimum imaging performance. Although we are using SPECT imaging as a platform to demonstrate the system optimization strategy, this development also provides a useful framework for system optimization problems in other modalities, such as positron emission tomography and x-ray computed tomography (Moore et al (2009 IEEE Nucl. Sci. Symp. Conf. Rec. pp 4154-7), Freed et al (2008 Med. Phys. 35 1912-25)).
在本文中，我们提出了一种分析方法，用于针对任意给定的系统参数集优化静态 SPECT 系统的设计或优化具有可变/自适应 SPECT 成像硬件的采样策略。该方法有三个关键方面。首先，它被设计为在离散化的系统参数空间中运行。其次，我们引入了虚拟探测器的人工概念作为成像系统的基本构建块。通过将 SPECT 系统描述为虚拟探测器的集合，可以将系统优化任务转换为在所有虚拟探测器上找到最佳成像时间分布（ITD）的过程。第三，优化问题（找到最佳 ITD）可以通过块迭代方法或其他非线性优化算法来解决。从本质上讲，所得最佳 ITD 可以提供虚拟探测器相对重要性（或有效性）的定量度量，并有助于识别导致最佳成像性能的系统配置或采样策略。虽然我们使用 SPECT 成像作为平台来演示系统优化策略，但这一发展也为正电子发射断层扫描和 X 射线计算机断层扫描等其他模态中的系统优化问题提供了有用的框架（Moore 等人，2009 IEEE Nucl. Sci. Symp. Conf. Rec. pp 4154-7，Freed 等人，2008 Med. Phys. 35 1912-25）。
