NEMA NU-4 Performance Evaluation of the IRIS PET/CT Preclinical Scanner

This paper presents the performance assessment study of the PET component of the IRIS PET/CT according to the National Electrical Manufacturers Association NU 4-2008 standard. The IRIS PET/CT is a high-resolution integrated system for PET and CT imaging of small animals. We evaluated the performance of the PET system, carrying out the following measures: spatial resolution, sensitivity, counting rate capabilities, and image quality parameters. Furthermore, two examples of in vivo experiments are shown. The average energy resolution for a whole module is 14% at 511 keV. The maximum absolute sensitivity for a point source at the center of the field-of-view is 8.0 ± 1.1% for 250-750 keV energy window and 6.6 ± 1.0% for 350-750 keV. The scatter fraction for mouse-like and rat-like phantoms are 15.6% (250-750 keV) and 22.4% (350-750 keV), respectively. Recovery coefficients were measured with the image-quality phantom, providing good results with an image uniformity of 7%. The imaging performance of the IRIS PET are confirmed in the animal experiments. With the IRIS PET/CT, it was possible to derive the time activity curve for various regions of interest with time frame duration down to 5 s, thus enabling the possibility to derive the tracer input function.