Euromedim 2006 :1st European Conference on Molecular Imaging Technology

Inter-crystal scatter identification for a depth-sensitive detector using support vector machine for small animal PET

9 May 2006, 14:00

1h

Palais du Pharo, Marseille

poster • Image reconstruction and processing Poster Session :Simulation, Modeling, Reconstruction

Speaker

Dr Eiji Yoshida (National Institute of Radiological Sciences)

Description

In a conventional PET detector, detected events are projected to 2D position histogram with Anger calculation for a crystal identification. However, the measured histogram is affected by inter-crystal scatterings (ICS) which occur in a whole detector. Peaks with projected each crystal in the histogram are blurred, and it causes ICS’s mispositioning. A depth of interaction (DOI) detector has been developed for the small animal PET scanner: jPET-RD. This DOI detector uses 32x32 crystals with four layers and a 256-channel multi-anode flat panel photomultiplier tube (FP-PMT) was developed by Hamamatsu Photonics K.K. Each crystal element is 1.45x1.45x4.5 mm. The FP-PMT has a large useful area (49x49 mm) and small anode pitch (3.04 mm). Therefore, the FP-PMT can extensively trace the behavior of incident gamma rays in the crystals including ICS. We therefore propose a novel method for ICS estimation using a statistical pattern recognition based on the support vector machine (SVM). In this study, we applied the SVM for discriminating photoelectric events from ICS events generated from multiple-anode outputs. The SVM was trained by uniform irradiation events generated from a detector simulator using Monte Carlo calculation. Initial result of ICS identification is about 80 % for non-training data. This method can archive a true subtraction of ICS from measured events, and it is also useful for random correction in PET.