High spatial resolution small animal YAP-PET

We are assembling a high resolution small animal PET scanner. The detector module is composed of a YAP : Ce matrix, consisting of 400 crystals 2×2×30 mm3 glued together, and optically isolated by a 5 μm thick reflective layer. The matrix is directly coupled to a position sensitive photomultiplier Hamamatsu mod. R2486-06 (PSPMT). Two detector modules are mounted on a rotating gantry. The opposite detectors can be positioned at a distance ranging from 5 to 25 cm so that the scanner transaxial FOV (Fiel Of View) is variable in the 2.5–15 cm range. The scanner axial FOV is 4 cm. The positron test source was 22Na. The system will operate in 3D data acquisition mode. The measured axial spatial resolution at the center using a simple back-projection planar reconstruction algorithm is 2.3 mm FWHM after correction for the PSPMT position nonlinearities and for source dimension. By eliminating the full-absorption events (mainly due to multiple interactions in the multi-crystals) the spatial resolution was improved to 1.8 mm. This result is very appropriate for small animal PET studies.