Pixel identification for small pitch scintillation crystal arrays

The present invention relates to a calibration method (100) for a gamma ray detector (3, 51) including a scintillator array (5) for emitting scintillation photons at photo conversion positions in response to incident gamma rays and a photodetector array (7) coupled thereto in light-sharing mode for determining a spatial intensity distribution of scintillation photons. The method comprises the steps of recording (S10) spatial intensity distributions of scintillation photons emitted by the scintillator array (5) in response to multiple incident gamma rays, determining (S22) sets of coincidently emitted scintillation photons from the recorded spatial intensity distributions, determining for the sets of coincidently emitted scintillation photons center-of-gravity positions (S24) and cumulative energies (S26), performing (S28) a clustering analysis based on the determined center-of-gravity positions and cumulative energies to obtain clusters (26a, 26b, 33) of gamma ray events attributed to a scintillator array ele