Design and characterization of IndyPET-II:A high-resolution, high-sensitivity dedicated research scanner

The IndyPET-II scanner has been developed as a high-resolution, high-sensitivity research PET scanner for use in small animal, intermediate sized animal, and small field of view human (brain, breast) imaging applications. The system consists of four, approximately plane detector banks mounted on a rotatable gantry. Overall these detectors cover a transaxial field of view (FOV) of 23 cm and an axial FOV of 15 cm. This configuration gives reduced parallax and approximately uniform resolution throughout the FOV. The two pairs of opposing detector banks are offset to give increased sampling density and increased resolution. Characterization measurements using the NEMA-2001 and NEMA-1994 standards are reported. In an axial plane, the averaged (radial and transverse) FWHM resolution is 2.5 mm at the center of the FOV and increases to less than 3.5 mm at the edge of the FOV. The NEMA-2001 sensitivity is 9030 cps/MBq at the center of the scanner and 4250 cps/MBq at r=10cm. The NEMA-1994 sensitivity is 23.0 cps/MBq/ml. Using the NEMA-2001 procedures, the peak true count rate is 95 kcps at an activity concentration of 10.4 kBq/ml and the peak NEC count rate is 31 kcps at an activity concentration of 5.4 kBq/ml. For the NEMA-1994 measurements, the peak true count rate is 130 kcps at a concentration of 18.6 kBq/ml. All measurements were performed using a 350-650 keV energy window.