NEMANU2-2001 guided performance evaluation of four Siemens ECAT PET-scanners

The NEMA NU 2-2001 protocol has been especially designed for the performance evaluation of whole body PET-measurements with scanners operated in the 3D-acquisition mode without septa or with septa retracted. This scanning mode is sensitive to radiation from outside the field of view. We report the comparative NU 2-2001 performance tests in respect to spatial resolution, sensitivity, scatter fraction and count rate capabilities which were done on four different Siemens ECAT PET-scanners, the two BGO scanners HR+ and EXACT and the two LSO scanners ACCEL and EMERGE. The HR+ showed a superior spatial resolution, whereas the ACCEL had the best count rate (NEC) performance above an activity concentration of 2 kBq/cc. Although the partial ring scanner EMERGE yields lower NEC rates than the EXACT for activity concentrations less than 10 kBq/cc, it is favorable beyond this cross over point. The scatter fraction of all four scanners was about 46%. The NU 2-2001 performance tests proved to be an excellent tool for this instrumental comparison.