Kalaitzidis Philip, Gustafsson Johan, Hindorf Cecilia, Ljungberg Michael
Medical Radiation Physics, Lund, Lund University, Lund, Sweden.
Department of Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Solna, Stockholm, Sweden.
Heliyon. 2022 Apr 21;8(4):e09316. doi: 10.1016/j.heliyon.2022.e09316. eCollection 2022 Apr.
The study aimed to create a pipeline from Monte Carlo simulated projections of a Gate PET system to reconstructed images. The PET system was modelled after the GE Discovery MI (DMI) PET/CT, and the simulated projections were reconstructed with the stand-alone reconstruction software CASToR. Attenuation correction, normalisation calibration, random estimation, and scatter estimation for the simulations were computed with in-house programs. The pipeline was compared in both projection and image space with data acquired on a clinical DMI and reconstructed with GE's off-line PET reconstruction software (PET Toolbox) and CASToR. The simulated and measured data were compared for the number of prompt coincidences, scatter fraction, contrast recovery coefficient (CRC), signal-to-noise ratio (SNR), background variability, residual lung error, and image profiles. A slight discrepancy was noted in the projection space, but good agreements were generally achieved in image space between simulated and measured data. The CRC was found to be 81 % for Gate - CASToR, 84 % for GE - CASToR, and 84 % for GE - PET Toolbox for the largest sphere of the NEMA image quality (IQ) phantom, and the SNR was found to be 98 for Gate - CASToR, 91 for GE - CASToR, and 93 for GE - PET Toolbox. Profiles drawn over the spheres for the NEMA IQ phantom and the Data Spectrum (DS) phantom show a good match between measurement and simulation. The results indicate feasibility to utilise the pipeline as a tool for off-line simulation-based studies. A complete pipeline introduces possibilities to study the impact of single parameters in the whole chain from simulation to reconstructed images.
该研究旨在创建一条从门控正电子发射断层扫描（Gate PET）系统的蒙特卡罗模拟投影到重建图像的流程。PET系统是仿照通用电气公司的Discovery MI（DMI）PET/CT进行建模的，模拟投影通过独立的重建软件CASToR进行重建。模拟的衰减校正、归一化校准、随机估计和散射估计使用内部程序进行计算。该流程在投影空间和图像空间中与在临床DMI上采集并使用通用电气公司的离线PET重建软件（PET Toolbox）和CASToR重建的数据进行了比较。比较了模拟数据和测量数据在真符合计数、散射分数、对比度恢复系数（CRC）、信噪比（SNR）、背景变异性、残余肺误差和图像轮廓方面的情况。在投影空间中发现了轻微差异，但在图像空间中模拟数据和测量数据总体上达成了良好的一致性。对于NEMA图像质量（IQ）体模的最大球体，发现Gate - CASToR的CRC为81%，GE - CASToR为84%，GE - PET Toolbox为84%；Gate - CASToR的SNR为98，GE - CASToR为91，GE - PET Toolbox为93。在NEMA IQ体模和数据谱（DS）体模的球体上绘制的轮廓显示测量值与模拟值匹配良好。结果表明将该流程用作基于离线模拟研究的工具是可行的。完整的流程为研究从模拟到重建图像的整个链条中单个参数的影响提供了可能性。
