Performance evaluation of the PET sub-systems of two PET/CT imagers according to NEMA standard NU 2-2001

Performance and image quality of PET scanners are mainly determined by the choice of the detector material and the realised design of the scanner. The aim of this study was to measure the PET performance characteristics of two state-of-the-art PET/CT Systems.

Performance measurements following the NEMA NU 2-2001 standard were performed on a GSO-based system and on a system with LSO detectors. The following parameters were determined: spatial resolution, scatter fraction, sensitivity and count rate behaviour A body phantom was used to determine the image quality as well as the influence of differently performed attenuation corrections (low dose CT vs. 137Cs transmission source).

Both scanners have partly different, but altogether good performance characteristics. The differences can be explained mostly by different physical properties of the detectors and by a different design of the scanners including the implemented electronics.

If the data are to be compared quantitatively, the modality of the attenuation correction has to be taken into account, especially in regions with reduced uptake or reduced density. Both scanners achieve a very good image quality rich in contrast within short acquisition times which allows easy detection of small lesions.