An integrated PET-SPECT small animal imager: preliminary results

We have successfully built and characterised a small animal PET based on 4 rotating detectors with a spatial resolution < 2 mm over its field of view and a sensitivity of 640 cps/mu Ci at the centre. The scanner is based on f our matrices of 400 YAP:Ce finger crystals (2x2x30 mm(3) each) coupled to P osition Sensitive PhotoMultipliers (Hamamatsu R2486-06.) We have now applied two high resolution collimators to two opposite detecto rs, hence realising an integrated PET-SPECT scanner for small animals. The collimators are made of lead with 20 mm long, 0.6 mm hexagonal holes with 0 .15mm septa. The read-out and data acquisition system are handled by NIM-CA MAC standard electronics. The Field Of View (FOV) of the tomograph has a di ameter of 4 cm and an axial length of 4 cm in both PET and SPECT configurat ion which is appropriate for mice and rat studies.