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 [is less than] 2 mm over its field of view and a sensitivity of 640 cps/[micro]Ci at the centre. The scanner is based on four matrices of 400 YAP:Ce finger crystals (2x2x30 [mm.sup.3] each) coupled to Position Sensitive PhotoMultipliers (Hamamatsu R2486-06.) We have now applied two high resolution collimators to two opposite detectors, 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 0.15 mm septa. The read-out and data acquisition system are handled by NIM-CAMAC standard electronics. The Field Of View (FOV) of the tomograph has a diameter of 4 cm and an axial length of 4 cm in both PET and SPECT configuration which is appropriate for mice and rat studies.