Characterization of a Large Volume Cadmium Zinc Telluride Preclinical PET System

Abstract

This work focuses on the performance characterization of a large volume CZT preclinical PET system. Two full heads of the final four-headed box-shaped system have been constructed with each head composed of 24 CZT crystals; each crystal is of size 40 x 40 x 5 mm3. Crystals are paired to form modules with an anode-cathode-cathode-anode configuration. Each CZT crystal has 39 anode strips, and 38 electrodes. Anode strips are 100 μm wide with a 1 mm pitch and steering electrode are 400 μm wide. The cathode side of the detector module is composed of 8 strips which are 4.9 mm wide with a pitch of 5 mm. Photons enter the crystal in an edge-on orientation and pass through the 5x40 mm2 edge, which results in a detection efficiency equivalent to that of 2 cm of LSO scintillator. The readout of the cathode and anode strips are supported by custom front end electronics designed around a readout ASIC. This configuration has 3456 readout channels with an effective 1872 anode channels and 384 cathode channels. We have begun characterizing the energy, coincidence timing, and spatial performance of the system. Results indicate that 70% of the anode channels in the system are producing energy resolvable photopeaks with an average percent energy resolution after charge trapping correction at 11.79 % ± 3.19 %.