VrPET/CT: Development of a rotating multimodality scanner for small-animal imaging

This work reports on the development and evaluation of the PET component of a PET/CT system for small-animal in-vivo imaging. The PET and CT subsystems are assembled in a rotary gantry in such a way that the center of rotation for both imaging modalities is mechanically aligned. The PET scanner configuration is based on 2 detector modules, each of which consist of 2 flat-panel type PS-PMTs (Hamamatsu, H8500) and 2 (30 × 30 elements) LYSO arrays. The dimension of the crystal matrix elements are 1.4 × 1.4 mm² in cross section and 12 mm in depth. The VrPET detector modules are positioned in opposite sides of a 140 mm diameter ring, providing a transaxial field of view of 86.6 mm diameter and an axial field of view of 45.6 mm. The experimental results obtained in the performance tests are transaxial resolution of 1.5 mm FWHM in the CFOV, and the axial resolution of 2.3 mm FWHM. The absolute coincidence sensitivity is 2.22 % for a coincidence window of 6 ns (100–700 keV). The imaging capability of the PET unit is demonstrated on phantom and animal studies.