Pfaehler Elisabeth, De Jong Johan R, Dierckx Rudi A J O, van Velden Floris H P, Boellaard Ronald
Departments of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
Department of Radiology, Section of Nuclear Medicine, Leiden University Medical Center, Leiden, The Netherlands.
EJNMMI Phys. 2018 Sep 18;5(1):16. doi: 10.1186/s40658-018-0215-x.
Positron-emission tomography (PET) simulators are frequently used for development and performance evaluation of segmentation methods or quantitative uptake metrics. To date, most PET simulation tools are based on Monte Carlo simulations, which are computationally demanding. Other analytical simulation tools lack the implementation of time of flight (TOF) or resolution modelling (RM). In this study, a fast and easy-to-use PET simulation-reconstruction package, SiMulAtion and ReconsTruction (SMART)-PET, is developed and validated, which includes both TOF and RM. SMART-PET, its documentation and instructions to calibrate the tool to a specific PET/CT system are available on Zenodo. SMART-PET allows the fast generation of 3D PET images. As input, it requires one image representing the activity distribution and one representing the corresponding CT image/attenuation map. It allows the user to adjust different parameters, such as reconstruction settings (TOF/RM), noise level or scan duration. Furthermore, a random spatial shift can be included, representing patient repositioning. To evaluate the tool, simulated images were compared with real scan data of the NEMA NU 2 image quality phantom. The scan was acquired as a 60-min list-mode scan and reconstructed with and without TOF and/or RM. For every reconstruction setting, ten statistically equivalent images, representing 30, 60, 120 and 300 s scan duration, were generated. Simulated and real-scan data were compared regarding coefficient of variation in the phantom background and activity recovery coefficients (RCs) of the spheres. Furthermore, standard deviation images of each of the ten statistically equivalent images were compared.
SMART-PET produces images comparable to actual phantom data. The image characteristics of simulated and real PET images varied in similar ways as function of reconstruction protocols and noise levels. The change in image noise with variation of simulated TOF settings followed the theoretically expected behaviour. RC as function of sphere size agreed within 0.3-11% between simulated and actual phantom data.
SMART-PET allows for rapid and easy simulation of PET data. The user can change various acquisition and reconstruction settings (including RM and TOF) and noise levels. The images obtained show similar image characteristics as those seen in actual phantom data.
正电子发射断层扫描（PET）模拟器常用于分割方法或定量摄取指标的开发和性能评估。迄今为止，大多数PET模拟工具基于蒙特卡罗模拟，计算量很大。其他分析模拟工具缺乏飞行时间（TOF）或分辨率建模（RM）的实现。在本研究中，开发并验证了一个快速且易于使用的PET模拟重建软件包，即模拟与重建（SMART）-PET，它同时包括TOF和RM。SMART-PET及其文档以及将该工具校准到特定PET/CT系统的说明可在Zenodo上获取。SMART-PET允许快速生成3D PET图像。作为输入，它需要一幅表示活度分布的图像和一幅表示相应CT图像/衰减图的图像。它允许用户调整不同参数，如重建设置（TOF/RM）、噪声水平或扫描持续时间。此外，可以包含随机空间偏移，以表示患者重新定位。为了评估该工具，将模拟图像与NEMA NU 2图像质量体模的实际扫描数据进行比较。扫描以60分钟列表模式进行，并在有和没有TOF和/或RM的情况下进行重建。对于每个重建设置，生成了十幅统计等效图像，分别代表30、60、120和300秒的扫描持续时间。比较了模拟数据和实际扫描数据在体模背景中的变异系数以及球体的活度恢复系数（RC）。此外，还比较了十幅统计等效图像中每一幅的标准差图像。
SMART-PET生成的图像与实际体模数据相当。模拟PET图像和实际PET图像的图像特征随重建协议和噪声水平的变化方式相似。随着模拟TOF设置的变化，图像噪声的变化遵循理论预期行为。模拟体模数据和实际体模数据之间，RC随球体大小的变化在0.3 - 11%范围内一致。
SMART-PET允许快速且轻松地模拟PET数据。用户可以更改各种采集和重建设置（包括RM和TOF）以及噪声水平。获得的图像显示出与实际体模数据相似的图像特征。
