A high resolution PET for animal studies

A new high resolution positron emission tomography (PET) system dedicated to in vivo animal studies has been developed. A block detector, which is a position-sensistive photomultiplier tube (Hamamatsu R3941-02) coupled to 4 arrays of 1.7 mm wide BGO crystals has been adopted to the system. There are 15 block detectors positioned to form a 35 em diameter ring, with the coupling of 4 BGO arrays to each PMT. This provides 4 detector rings, giving the system a 7 slice imaging capability. The gantry head tilts up to [+ or - ]90 [degrees], and is capable of moving up and down by 30 cm. These positioning capabilities allow flexibility and great ease of use in subject positioning. Also, a gantry entrance size of 22 cm in diameter allows studies ranging from rats and mice to primates such as Rhesus and squirrel monkeys. The physical performance of the system has been evaluated. The spatial resolution in the center of the field of view (FOV) is 3.0 mm at full width at half maximum (FWHM) in the transaxial plane. The axial resolution at the center of the FOV is 4.8 mm FWHM in the direct plane, and 4.1 mm FWHM in the cross plane. The total system sensitivity is 20.7 kcps/[mu]Ci/ml for a 10 cm diameter cylindrical uniform phantom with an energy threshold of 300 keV.