Sadremomtaz Alireza, Telikani Zeinab
Department of Physics, Faculty of Science, University of Guilan, Namjoo Avenue, P.O. Box 41635-1914, Rasht, Iran.
Nucl Med Mol Imaging. 2018 Aug;52(4):303-310. doi: 10.1007/s13139-018-0530-0. Epub 2018 Jun 21.
This study aims to compare Monte Carlo-based codes' characteristics in the determination of the basic parameters of a high-resolution single photon emission computed tomography (HiReSPECT) scanner.
The geometry of this dual-head gamma camera equipped with a pixelated CsI(Na) scintillator and lead hexagonal hole collimator were accurately described in the GEANT4 Application for the Tomographic Emission (GATE), Monte Carlo N-particle extended (MCNP-X), and simulation of imaging nuclear detectors (SIMIND) codes. We implemented simulation procedures similar to the experimental test for calculation of the energy spectra, spatial resolution, and sensitivity of HiReSPECT by using Tc sources.
The energy resolutions simulated by SIMIND, MCNP-X, and GATE were 17.53, 19.24, and 18.26%, respectively, while it was calculated at 19.15% in experimental test. The average spatial resolutions of the HiReSPECT camera at 2.5 cm from the collimator surface simulated by SIMIND, MCNP-X, and GATE were 3.18, 2.9, and 2.62 mm, respectively, while this parameter was reported at 2.82 mm in the experiment test. The sensitivities simulated by SIMIND, MCNP-X, and GATE were 1.44, 1.27, and 1.38 cps/μCi, respectively, on the collimator surface.
Comparison between simulation and experimental results showed that among these MC codes, GATE enabled to accurately model realistic SPECT system and electromagnetic physical processes, but it required more time and hardware facilities to run simulations. SIMIND was the most flexible and user-friendly code to simulate a SPECT camera, but it had limitations in defining the non-conventional imaging device. The most important characteristics like time and speed of simulation, preciseness of results, and user-friendliness should be considered during simulations.
本研究旨在比较基于蒙特卡罗方法的代码在确定高分辨率单光子发射计算机断层扫描（HiReSPECT）扫描仪基本参数方面的特性。
在GEANT4断层发射应用程序（GATE）、蒙特卡罗N粒子扩展程序（MCNP-X）和成像核探测器模拟程序（SIMIND）中准确描述了这款配备像素化碘化铯钠（CsI(Na)）闪烁体和铅六边形孔准直器的双头伽马相机的几何结构。我们通过使用锝源实施了类似于实验测试的模拟程序，以计算HiReSPECT的能谱、空间分辨率和灵敏度。
SIMIND、MCNP-X和GATE模拟的能量分辨率分别为17.53%、19.24%和18.26%，而实验测试中计算得出的能量分辨率为19.15%。SIMIND、MCNP-X和GATE模拟的HiReSPECT相机在距准直器表面2.5厘米处的平均空间分辨率分别为3.18毫米、2.9毫米和2.62毫米，而实验测试中该参数报告为2.82毫米。SIMIND、MCNP-X和GATE在准直器表面模拟的灵敏度分别为1.44 cps/μCi、1.27 cps/μCi和1.38 cps/μCi。
模拟结果与实验结果的比较表明，在这些蒙特卡罗代码中，GATE能够准确地对实际的单光子发射计算机断层扫描（SPECT）系统和电磁物理过程进行建模，但运行模拟需要更多时间和硬件设施。SIMIND是模拟SPECT相机最灵活且用户友好的代码，但在定义非常规成像设备方面存在局限性。在模拟过程中应考虑诸如模拟时间和速度、结果精度以及用户友好性等最重要的特性。
