Initial evaluation of the Indiana small animal PET scanner

The Indiana small animal PET scanner is a new generation PET scanner with design goals of 1 microliter volumetric spatial resolution, a point source sensitivity of greater than 5 percent, and an imaging field-of-view suitable for whole body mouse imaging. The scanner design uses 12 planar detector banks each consisting of a 48 × 108 array of 20 mm long LSO crystals with an array pitch of 0.87 mm coupled to two Hamamatsu H8500 large area, 64-anode photomultiplier tubes. The detector modules are mounted on a rotatable gantry and are offset from the center of rotation to give an increased sampling density. Eight detector banks are currently installed in the scanner, and this report presents an initial performance evaluation of the scanner for this configuration. Using a 30 gauge needle (ID=0.15 mm, OD=0.30 mm) positioned near the center of the scanner, the transaxial resolution has been measured to be 1.1 mm FWHM and the axial resolution has been measured to be 1.5 mm FWHM. The sensitivity has been measured to be 4.0% of all decays. The scatter fraction is 0.26 and the peak noise equivalent countrate is 80 kcps at an activity of 0.22 mCi. Sample images demonstrate good imaging capabilities.