Ptáček Jaroslav, Karhan Pavel, Fiala Petr
Department of Medical Physics and Radiation Protection, University Hospital Olomouc, Olomouc, Czech Republic; Clinic of Nuclear Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, Olomouc, Czech Republic.
Department of Medical Physics and Radiation Protection, University Hospital Olomouc, Olomouc, Czech Republic; Clinic of Nuclear Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, Olomouc, Czech Republic.
Phys Med. 2017 Jul;39:95-99. doi: 10.1016/j.ejmp.2017.06.002. Epub 2017 Jun 7.
The aim of this study was to determine the optimal image matrix and half-width of the Gaussian filter after iterative reconstruction of the PET image with point-spread function (PSF) and time-of-flight (TOF) correction, based on measuring the recovery coefficient (RC) curves. The measured RC curves were compared to those from an older system which does not use PSF and TOF corrections.
The measurements were carried out on a NEMA IEC Body Phantom. We measured the RC curves based on SUV and SUV in source spheres with different diameters. The change in noise level for different reconstruction parameter settings and the relation between RC curves and the administered activity were also evaluated.
With an increasing size of image matrix and reduction in the half-width of the post-reconstruction Gaussian filter, there was a significant increase in image noise and overestimation of the SUV. The local increase in SUV, observed for certain filtrations and objects with a diameter below 13mm, was caused by PSF correction. The decrease in administered activity, while maintaining the same conditions of acquisition and reconstruction, also led to overestimation of readings of the SUV and additionally to deterioration in reproducibility.
This study proposes a suitable size for the image matrix and filtering for displaying PET and SUV measurements. The benefits were demonstrated as improved image parameters for the newer instrument, these even being found using relatively strong filtration of the reconstructed images.
本研究的目的是在基于测量恢复系数（RC）曲线对正电子发射断层显像（PET）图像进行带点扩散函数（PSF）和飞行时间（TOF）校正的迭代重建后，确定最佳图像矩阵和高斯滤波器的半高宽。将测量得到的RC曲线与来自未使用PSF和TOF校正的旧系统的曲线进行比较。
测量在NEMA IEC体模上进行。我们基于不同直径源球体内的标准化摄取值（SUV）和SUV测量了RC曲线。还评估了不同重建参数设置下噪声水平的变化以及RC曲线与注入活度之间的关系。
随着图像矩阵尺寸的增加和重建后高斯滤波器半高宽的减小，图像噪声显著增加且SUV被高估。对于某些滤波以及直径小于13mm的物体观察到的SUV局部增加是由PSF校正引起的。在保持相同采集和重建条件的情况下，注入活度的降低也导致SUV读数被高估，并且还导致重现性变差。
本研究提出了适合显示PET和SUV测量结果的图像矩阵大小和滤波方法。对于更新的仪器，这些方法的益处表现为图像参数得到改善，甚至在对重建图像使用相对较强滤波的情况下也能发现这些益处。
