University of Lyon, Université Claude Bernard Lyon 1, CNRS-IN2P3, Institut de Physique Nucléaire de Lyon, F-69622, Villeurbanne, France.
Phys Med Biol. 2017 Nov 9;62(23):8794-8812. doi: 10.1088/1361-6560/aa926a.
Single photon emission computed tomography (SPECT) is at present one of the major techniques for non-invasive diagnostics in nuclear medicine. The clinical routine is mostly based on collimated cameras, originally proposed by Hal Anger. Due to the presence of mechanical collimation, detection efficiency and energy acceptance are limited and fixed by the system's geometrical features. In order to overcome these limitations, the application of Compton cameras for SPECT has been investigated for several years. In this study we compare a commercial SPECT-Anger device, the General Electric HealthCare Infinia system with a High Energy General Purpose (HEGP) collimator, and the Compton camera prototype under development by the French collaboration CLaRyS, through Monte Carlo simulations (GATE-GEANT4 Application for Tomographic Emission-version 7.1 and GEANT4 version 9.6, respectively). Given the possible introduction of new radio-emitters at higher energies intrinsically allowed by the Compton camera detection principle, the two detectors are exposed to point-like sources at increasing primary gamma energies, from actual isotopes already suggested for nuclear medicine applications. The Compton camera prototype is first characterized for SPECT application by studying the main parameters affecting its imaging performance: detector energy resolution and random coincidence rate. The two detector performances are then compared in terms of radial event distribution, detection efficiency and final image, obtained by gamma transmission analysis for the Anger system, and with an iterative List Mode-Maximum Likelihood Expectation Maximization (LM-MLEM) algorithm for the Compton reconstruction. The results show for the Compton camera a detection efficiency increased by a factor larger than an order of magnitude with respect to the Anger camera, associated with an enhanced spatial resolution for energies beyond 500 keV. We discuss the advantages of Compton camera application for SPECT if compared to present commercial Anger systems, with particular focus on dose delivered to the patient, examination time, and spatial uncertainties.
单光子发射计算机断层扫描（SPECT）是目前核医学中用于非侵入性诊断的主要技术之一。临床常规主要基于 Hal Anger 最初提出的准直相机。由于存在机械准直，检测效率和能量接受受到系统几何特征的限制和固定。为了克服这些限制，几年来一直在研究用于 SPECT 的康普顿相机的应用。在这项研究中，我们通过蒙特卡罗模拟（GATE-GEANT4 Application for Tomographic Emission-version 7.1 和 GEANT4 version 9.6）比较了商业 SPECT-Anger 设备，即通用电气医疗保健 Infinia 系统和高能通用目的（HEGP）准直器，以及由法国合作 CLaRyS 开发的康普顿相机原型。考虑到康普顿相机检测原理本身允许更高能量的新放射性示踪剂的引入，两个探测器分别暴露于点状源，伽马射线能量逐渐增加，从已经建议用于核医学应用的实际同位素开始。首先通过研究影响其成像性能的主要参数来对康普顿相机原型进行 SPECT 应用的特征描述：探测器能量分辨率和随机符合率。然后，根据 Anger 系统的伽马透射分析获得的径向事件分布、检测效率和最终图像，以及使用迭代列表模式-最大似然期望最大化（LM-MLEM）算法对康普顿重建进行比较，比较了两种探测器的性能。结果表明，与 Anger 相机相比，康普顿相机的检测效率提高了一个数量级以上，对于超过 500keV 的能量，空间分辨率也得到了提高。我们讨论了与目前商业 Anger 系统相比，康普顿相机应用于 SPECT 的优势，特别关注患者接受的剂量、检查时间和空间不确定性。
