Department of Physics, Royal Institute of Technology (KTH), Albanova University Center, SE-106 91 Stockholm, Sweden.
IEEE Trans Med Imaging. 2010 Jul;29(7):1390-400. doi: 10.1109/TMI.2010.2047113. Epub 2010 Apr 8.
The pinhole camera in single photon emission computed tomography (SPECT) has an inherent trade-off between resolution and sensitivity. Recent systems overcome this to some extent by utilizing multiple pinholes distributed around the imaging object. The present work is a theoretical study on how to optimally construct such systems. We use an analytic model to analyze the multipinhole SPECT geometry and identify the underlying trade-offs. One of the results is the derivation of the upper bound for the sensitivity, given the geometric resolution and field-of-view (FOV). Reaching this bound requires an infinitely large detector. However, a sensitivity very close to the upper bound can be achieved by a system with realistic proportions. We show that it is usually possible to get a sensitivity that is 95%-99% of the upper bound. Further analysis reveals a trade-off between sensitivity, magnification, and the number of pinholes. Based on this new theory, we develop a strategy for multipinhole SPECT design, from which a number of example systems are computed. Penetration in the pinhole knife edge is accounted for by using the resolution and sensitivity equivalent apertures.
单光子发射计算机断层扫描 (SPECT) 中的针孔相机在分辨率和灵敏度之间存在固有权衡。最近的系统通过利用分布在成像物体周围的多个针孔在某种程度上克服了这一问题。本工作是对如何最优地构建此类系统的理论研究。我们使用解析模型来分析多针孔 SPECT 几何形状并确定潜在的权衡。结果之一是在给定几何分辨率和视野 (FOV) 的情况下，灵敏度的上限。达到这个上限需要一个无限大的探测器。然而，通过具有现实比例的系统可以实现非常接近上限的灵敏度。我们表明，通常可以获得灵敏度为上限的 95%-99%。进一步的分析揭示了灵敏度、放大率和针孔数量之间的权衡。基于这一新理论，我们开发了一种多针孔 SPECT 设计策略，并计算了一些示例系统。通过使用分辨率和灵敏度等效孔径来考虑针孔刀边缘的穿透。
