DST and DCT-based Depth of Interaction (DOI) Determining Techniques for LSO and LuYAP Scintillation Detectors in PET

The absorption of radiation in multicrystal PET detectors results in different decay-time pulses. The differences between these pulse decay time constants are used to discriminate between different scintillator materials. In this paper, pulse shape discrimination (PSD) techniques based on the discrete sine transform (DST) and discrete cosine transform (DCT) are proposed. These transformations are used to extract frequencydomain features for discrimination. Comparison of the proposed PSD techniques was performed on digitized pulses from the LSO/LuYAP phoswich detector. The comparison between different DSTand DCT-types turned out that DST-type 3 gives the best PSD efficiency of 98.79%, while DCT-type 2 gives 98.12%. General Terms Positron Emission Topography, algorithms.