Preliminary performance characterization of DbPET2.1, a PET scanner dedicated to the imaging of the breast and extremities

The combined effort of several laboratories at our institution resulted in the building of the first high-resolution PET/CT prototype dedicated to imaging the extremities of the body. Ongoing clinical trials for breast-cancer diagnosis and assessment of the response to treatment underlined the need for a second-generation prototype with improved electronics and spatial resolution. A preliminary version has been assembled and fully characterized. In this work, we present further improvements in detector performance, as well as the readout electronics for the PET component. The detector consists of a 16 × 16 array of 1.27 × 1.27 × 20 mm 3 lutetium yttrium orthosilicate crystals, the smallest crystal size for completed breast PET prototypes to date, directly coupled to a position-sensitive photomultiplier tube (PSPMT). The scintillator crystals are polished on all six faces and separated by a ∼70 μ m enhanced specular reflector. The readout electronics were redesigned to reduce their footprint and improve timing resolution. We report a detector energy and timing resolution of 12% and 1.0 ns, respectively, and an average intrinsic spatial resolution of 1.29 mm (central row in one detector array). The new PET/CT has been fully assembled, and initial system characterization is being performed. We report a system energy resolution of 15.7%, a timing resolution of 1.5 ns and a filtered back-projection image spatial resolution in the center of the field of view of 1.6 mm.