A Mohymen Ahmed, Farag Hamed I, Reda Sameh M, Monem Ahmed S, Ali Said A
Nuclear Medicine and Radiation Therapy Department, National Cancer Institute, Cairo University, Cairo, Egypt.
Nuclear Medicine and Radiation Therapy Department, National Cancer Institute, Cairo University, Cairo, Egypt.
Appl Radiat Isot. 2025 Jun;220:111761. doi: 10.1016/j.apradiso.2025.111761. Epub 2025 Feb 27.
Using National Electrical Manufacturers Association (NEMA) phantom, the behavior of four distinct Positron Emission Tomography/Computed Tomography (PET/CT) reconstruction algorithms was investigated. These reconstruction algorithms were (Ordered Subset Expectation Maximization (OSEM), OSEM+ (Point Spread Function) PSF, OSEM + Time of Flight (TOF), and OSEM + TOF + PSF), and the focus was on sphere sizes and SBRs using recovery coefficients as a quantitation method. The obtained results demonstrated the significant effect of TOF on Gibbs artifact and Partial Volume Effect (PVE) at various Sphere-to-Background Ratios (SBRs). TOF-based algorithms improved quantification accuracy and mitigated the influence of Gibbs artifact, particularly at higher SBRs. Compared to PSF algorithm, TOF- based algorithms effectively mitigated the impact of PVE on small-sized spheres and less dependent on SBRs. In terms of Standardized Uptake Value (SUV) quantification, SUVmean was better when utilizing TOF-based algorithms at lower SBRs, whereas SUVmax at higher SBRs. The combination of TOF and PSF produced a promising outcomes in quantifying and detecting a small-sized spheres across various SBRs, ultimately resulting in a more reliable and precise diagnostic information.
使用美国国家电气制造商协会（NEMA）体模，研究了四种不同的正电子发射断层扫描/计算机断层扫描（PET/CT）重建算法的性能。这些重建算法分别是（有序子集期望最大化算法（OSEM）、OSEM+（点扩散函数）PSF、OSEM + 飞行时间（TOF）以及OSEM + TOF + PSF），并且以恢复系数作为定量方法，重点研究了球体大小和标准化摄取值比（SBR）。所得结果表明，在不同的球体与背景比值（SBR）下，飞行时间（TOF）对吉布斯伪影和部分容积效应（PVE）有显著影响。基于TOF的算法提高了定量准确性，并减轻了吉布斯伪影的影响，尤其是在较高的SBR值时。与PSF算法相比，基于TOF的算法有效减轻了PVE对小尺寸球体的影响，且对SBR的依赖性较小。在标准化摄取值（SUV）定量方面，在较低SBR值时使用基于TOF的算法时，SUV均值表现更好，而在较高SBR值时SUV最大值表现更好。TOF和PSF的组合在量化和检测不同SBR值下的小尺寸球体方面产生了良好的结果，最终得到了更可靠、精确的诊断信息。
