PERFORMANCE-CHARACTERISTICS OF A WHOLE-BODY PET SCANNER

Methods: This study characterizes the performance of a newly developed whole-body PET scanner (Advance, General Electric Medical Systems, Mi lwaukee, WI). The scanner consists of 12,096 bismuth germanate crystal s (4.0 mm transaxial by 8.1 mm axial by 30 mm radial) in 18 rings, giv ing 35 two-dimensional image planes through an axial field of view of 15.2 cm. The rings are separated by retractable tungsten septa Intrins ic spatial resolution, scatter fraction, sensitivity, high count rate performance and image quality are evaluated. Results: Transaxial resol ution (in FWHM) is 3.8 mm at the center and increases to 5.0 mm tangen tial and 7.3 mm radial at R = 20 cm. Average axial resolution decrease s from 4.0 mm FWHM at the center to 6.6 mm at R = 20 cm. Scatter fract ion is 9.4% and 10.2% for direct and cross slices, respectively. With septa out, the average scatter fraction is 34%. Total system sensitivi ty for true events (in kcps/(mu Ci/cc)) is 223 with septa in and 1200 with septa out. Dead-time losses of 50% correspond to a radioactivity concentration of 4.9 (0.81) mu Ci/cc and a true event count rate of 48 9 (480) kcps with septa in (out). Noise-equivalent count rate (NECR) f or the system as a whole shows a maximum of 261 (159) kcps at a radioa ctivity concentration of 4.1 (0.65) mu Ci/cc with septa in (out). NECR is insensitive to changes in lower gamma-energy discrimination betwee n 250-350 keV. Conclusions: The results show the performance of the ne wly designed PEI scanner to be well suited for clinical and research a pplications.