Implementation and Evaluation of a 3D-dependend Energy-Calibration Algorithm, including Interpolation Methods for missing read-out Channels

Abstract

In PET, a clear discrimination of scattered events to non-scattered events is crucial to reconstruct an image with high signal to noise ratio. Therefore, a precise energy estimation for all detected gamma interactions is necessary. In particular, light sharing detectors profit from 3D-dependend energy calibration. This work presents a generic position-dependent energy calibration algorithm exemplary for light sharing detector composed out of eight monolithic LYSO slabs read out by digital SiPMs (DPC 3200-22, PDPC). The algorithm splits the whole scintillation volume into virtual sub-volumes (voxel) and performs an energy calibration for each voxel individually. All 16 DPCs are self-triggering, so it is possible for one gamma interaction to not trigger all DPC located beneath the hit slab. The calibration step only considers events that had a full readout. For events with missing channel information, the missing energy contribution needs to be accounted for. This work presents approaches based on an analytical average light distribution and k-Nearest-Neighbor (kNN) to impute these on voxel level. The overall energy resolution of the uncalibrated photon-spectrum was 13.5%, the presented algorithm improves that to close to 11% in the energy spectrum by applying an 8x13x5 voxelization and using the kNN-interpolation method on the 5% of gamma interactions that have partially missing channel information.

Authors 5

1. M. Bovelett Aachen Department of Physics of Molecular Imaging

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen,Department of Physics of Molecular Imaging,Aachen,North Rhine-Westphalia,Germany

   Department of Physics of Molecular Imaging, RWTH Aachen, Aachen, North Rhine-Westphalia, Germany

2. Yannick Kuhl Aachen Department of Physics of Molecular Imaging

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen,Department of Physics of Molecular Imaging,Aachen,North Rhine-Westphalia,Germany

   Department of Physics of Molecular Imaging, RWTH Aachen, Aachen, North Rhine-Westphalia, Germany

3. Stephan Naunheim Aachen Department of Physics of Molecular Imaging

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen,Department of Physics of Molecular Imaging,Aachen,North Rhine-Westphalia,Germany

   Department of Physics of Molecular Imaging, RWTH Aachen, Aachen, North Rhine-Westphalia, Germany

4. David Schug Aachen Department of Physics of Molecular Imaging

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen,Department of Physics of Molecular Imaging,Aachen,North Rhine-Westphalia,Germany

   Department of Physics of Molecular Imaging, RWTH Aachen, Aachen, North Rhine-Westphalia, Germany

   Hyperion Hybrid Imaging Systems, Aachen, North Rhine-Westphalia, Germany

5. Volkmar Schulz Aachen Department of Physics of Molecular Imaging

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen,Department of Physics of Molecular Imaging,Aachen,North Rhine-Westphalia,Germany

   Department of Physics of Molecular Imaging, RWTH Aachen, Aachen, North Rhine-Westphalia, Germany

   Hyperion Hybrid Imaging Systems, Aachen, North Rhine-Westphalia, Germany