A small diameter positron emission tomograph (PET) dedicated to animal imaging using BaF2 crystals and a photosensitive wire chamber with tetrakis-dimethylamine-ethylene (TMAE), has been designed and built. It consists of a cylindrical ring with an internal diameter of 20 cm containing 2958 BaF2 crystals. The lack of septa in the design allows for 3-dimensional data aquisition and reconstruction.
The physical characteristics are as follows:
the detection efficiency for one 511 keV photon is 38%;
the sensitivity as measured with a 68 Ge point source at the centre is 32000 cps per MBq;
the tangential resolution (FWHM) varies from 2.6 mm at the centre to 4.5mm at a position 50 mm radially off centre;
the radial resolution (FWHM) varies from 2.6 mm at the centre to 6.4 mm at 50 mm radially off centre and the axial resolution is 3.5 mm;
the coincidence time resolution (FWHM) is 19 ns, which allows the use of a time window of 25 ns.
Good quality of tumour bearing rats have been recorded.