Experimental Validation of a Rodent PET Scanner Prototype Based on a Single LYSO Crystal Tube

Improving sensitivity and spatial resolution in small animal positron emission tomography imaging instrumentation constitutes one of the main goals of nuclear imaging research. These parameters are degraded by the presence of gaps between the detectors. The present manuscript experimentally validates our prototype of an edge-less preclinical PET system based on a single LYSO:Ce annulus with an inner diameter of 62 mm and ten outer facets of
$26\times52$
mm
²
. Scintillation light is read out by arrays of
$8\times8$
SiPMs coupled to the facets, using a projection readout of the rows and columns signals. The readout provides an accurate depth of interaction (DOI). We have implemented a calibration that mitigates the DOI-dependency of the transaxial and axial impact coordinates, and the energy photopeak gain. An energy resolution of 23.4 ± 1.8% was determined. The average spatial resolution of 1.4 ± 0.2 and 1.3 ± 0.4 mm FWHM were achieved for the radial and axial directions, respectively. We found a peak sensitivity of 3.8% at the system center, and a maximum NECR at 40.6 kcps for 0.27 mCi. The image quality (IQ) was evaluated using reconstructed images of an array of sources and the NEMA IQ phantom was also studied.