Previously, we proposed an 8-layer depth-of- interaction (DOI)encoding method for a PET detector and proved its validity. The layer ofinteraction is identified by hybrid method; the scintillation light controlby the original reflector arrangement for 4-layer DOI encoding and the pulseshape discrimination for 2-layer DOI encoding. Four layers then consist ofthe scintillator of different pulse shape from the scintillator for theother four layers. We investigated the effect of crystal arrangement difference ondetector performance to optimize the DOI detector. The two kind layers canbe arranged in two ways; stacked alternately or set in the upper and lowerfour layers respectively. Since the two crystal arrangements are supposed toshow different detector performance, we measured it on each arrangement. Theresults show better performance of the stacked arrangement in pulse shapediscrimination, while inferior in crystal identification among the same kindscintillation crystals composing four layers. There was no particulardifference between the two crystal arrangements in light outputs and energyresolutions of each layer.IEEE 2006 Nuclear Science Symposium and Medical Imaging Conferenc
