This study proposed and examined a new approach employing the light sharing PET detector configuration with thick light guide and GAPD array having large-area microcells for high effective quantum efficiency.

The number of counted photons was considerably increased and the LCE of 40% could be obtained with the detector configuration. The flood histogram showed good separation and wide margins between the spots of the scintillators. Moreover, a considerable improvement in the energy linearity performance was observed, and severe saturation effects could be clearly avoided.

This study demonstrated that GAPDs with large-area microcells, which have not been actively studied as PET photosensors because of their non-linearity properties, could be utilized for PET applications and even high photon flux regime.