A high resolution PET for animal studies

A high-resolution positron emission tomography (PET) system for in vivo animal studies was developed. A block detector, which is a position-sensitive photomultiplier tube (Hamamatsu R3941-02) coupled to four arrays of 1.7-mm-wide BGO crystals, was used. There are 15 block detectors positioned to form a 35-cm-diameter ring, with the coupling of four BGO arrays to each photomultiplier tube. This provides four detector rings, giving the system a seven-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 ease of use in subject positioning. A gantry entrance 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 was 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 Si/ml for a 10-cm-diameter cylindrical uniform phantom with a energy threshold of 300 keV.<>