TOF-PET Image Reconstruction With Multiple Timing Kernels Applied on Cherenkov Radiation in BGO

IEEE Transactions on Radiation and Plasma Medical Sciences, vol. 5, pp. 703–711

Abstract

Today Time-of-Flight (TOF), in PET scanners, assumes a single, well-defined timing resolution for all events. However, recent BGO-Cherenkov detectors, combining prompt Cherenkov emission and the typical BGO scintillation, can sort events into multiple timing kernels, best described by the Gaussian mixture models. The number of Cherenkov photons detected per event impacts directly the detector time resolution and signal rise time, which can later be used to improve the coincidence timing resolution. This work presents a simulation toolkit which applies multiple timing spreads on the coincident events and an image reconstruction that incorporates this information. A full cylindrical BGO-Cherenkov PET model was compared, in terms of contrast recovery and contrast-to-noise ratio, against an LYSO model with a time resolution of 213 ps. Two reconstruction approaches for the mixture kernels were tested: 1) mixture Gaussian and 2) decomposed simple Gaussian kernels. The decomposed model used the exact mixture component applied during the simulation. Images reconstructed using mixture kernels provided similar mean value and less noise than the decomposed. However, typically, more iterations were needed. Similarly, the LYSO model, with a single TOF kernel, converged faster than the BGO-Cherenkov with multiple kernels. The results indicate that the model complexity slows down convergence. However, due to the higher sensitivity, the contrast-to-noise ratio was 26.4% better for the BGO model.

Authors 6

1. Nikos Efthimiou

   University of Hull · University of Pennsylvania

   Affiliation as printed

   Department Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 USA

   PET Research Centre, Faculty of Health Sciences, University of Hull, Hull, U.K

   Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA

2. N. Kratochwil

   University of Vienna · European Organization for Nuclear Research

   Affiliation as printed

   University of Vienna, 1010 Vienna, Austria

   European Organization for Nuclear Research, Geneva, Switzerland

   University of Vienna, Vienna, Austria

3. S. Gundacker Aachen Department of Physics of Molecular Imaging Systems Institute for Experimental Molecular Imaging

   University of Milano-Bicocca · European Organization for Nuclear Research · RWTH Aachen University

   Affiliation as printed

   Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, 52062 Aachen, Germany

   European Organization for Nuclear Research, Geneva, Switzerland

   Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, Germany

   University of Milano-Bicocca, Milan, Italy

4. Andrea Polesel

   University of Milano-Bicocca · European Organization for Nuclear Research

   Affiliation as printed

   Physics Department, University of Milano-Bicocca, 20126 Milan, Italy

   European Organization for Nuclear Research, Geneva, Switzerland

   University of Milano-Bicocca, Milan, Italy

5. E. Auffray

   European Organization for Nuclear Research

   Affiliation as printed

   European Organization for Nuclear Research, 1211 Geneva, Switzerland

   European Organization for Nuclear Research, Geneva, Switzerland

6. Marco Pizzichemi

   University of Milano-Bicocca · European Organization for Nuclear Research

   Affiliation as printed

   Physics Department, University of Milano-Bicocca, 20126 Milan, Italy

   European Organization for Nuclear Research, Geneva, Switzerland

   University of Milano-Bicocca, Milan, Italy