HIGH-SPATIAL-RESOLUTION SMALL ANIMAL YAP-PET

We are assembling a high resolution small animal PET scanner. The dete ctor module is composed of a YAP:Ce matrix, consisting of 400 crystals 2 x 2 x 30 mm(3) glued together, and optically isolated by a 5 mu m t hick reflective layer. The matrix is directly coupled to a position se nsitive photomultiplier Hamamatsu mod. R2486-06 (PSPMT). Two detector modules are mounted on a rotating gantry. The opposite detectors can b e 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 Na-22. The sy stem will operate in 3D data acquisition mode. The measured axial spat ial resolution at the center using a simple back-projection planar rec onstruction algorithm is 2.3 mm FWHM after correction for the PSPMT po sition nonlinearities and for source dimension. By eliminating the ful l-absorption events (mainly due to multiple interactions in the multi- crystals) the spatial resolution was improved to 1.8 mm. This result i s very appropriate for small animal PET studies. (C) 1998 Elsevier Sci ence B.V. All rights reserved.