PHYSICAL CHARACTERISTICS OF TTV03, A NEW HIGH SPATIAL-RESOLUTION TIME-OF-FLIGHT POSITRON TOMOGRAPH

We present TTV03, a new high spatial resolution TOF-PET system. The machine consists of four 89 cm diameter rings made of 7 mm wide, 18 mm high and 45 mm deep BaF2 crystals (324 per ring) individually coupled to 11 mm diameter phototubes. The transaxial resolution (FWHM) in the reconstructed image is 5.7 mm at center, 5.7 mm (tangential) and 6.5 mm (radial) at 10 cm. The axial resolution is 8.8 mm (direct plane) and 6.7 mm (crossplane) at center, 10.3 mm (direct) and 11.2 mm (cross) at 10 cm from center. With a 150 keV threshold, the time-of-flight resolution is 750 psec (FWHM), and, with a 4.18 nsec coincidence window, the sensitivity (true evts/sec per µCi/cc) is 9800 (direct plane) and 14300 (crossplane). At 1µCi/cc, the ratio of random events to true events is.20 for the total and.03 per image element, and the scatter fraction is 22%. Dead time losses are 8.3% at 2.5 µCi/cc (4 rings) but the tomograph can handle activities over 50 µCi/cc in small regions with negligible losses. These characteristics make TTV03 particularly suitable for dynamic brain and heart H215O bolus studies. Copyright © 1990 by The Institute of Electrical and Electronics Engineers, Inc.