Performance of a 0.4 mm Pixelated Ce:GAGG Block Detector with Digital Silicon Photomultiplier

The intrinsic spatial resolution of the detector is an important aspect to reconstruct high quality nuclear medicine images. In order to realize a high spatial resolution, small pixelated Cerium doped Gd₃Al₂Ga₃O₁₂ (Ce:GAGG) scintillators-known for their high light output, high density and relatively fast decay time, were coupled to a digital silicon photomultiplier (dSiPM) for read out. This detector module consists of a 24×24 Ce:GAGG scintillator block of 0.4 mm×0.4mm ×5mm crystal elements and a 2 mm thick light guide made of acrylic resin. The digital silicon photomultiplier (dSiPM), DPC-3200-22-44, was used to acquire 2-D position histogram, energy resolution and coincidence timing resolution. The 2-dimensional position histogram of the Ce:GAGG block detector irradiated with ²²Na gamma photons showed that most pixels were clearly resolved with an average peak-to-valley (P/V) ratio of 3.4. The average energy resolution of the Ce:GAGG block detector was 17.8%. At trigger scheme 1 (1^st photon trigger), the coincidence timing resolution was 342 ± 7 ps FHWM when acquired in coincidence with a 2 mm×2mm×6mm LSO crystal (after skew correction). This study demonstrates that a pixelated Ce:GAGG block coupled with dSiPM provides good position performance and time resolution. We conclude that the highly pixelated Ce:GAGG detector module may be a good candidate for implementing ultrahigh resolution nuclear medicine systems and applications requiring good timing resolution.