Image reconstruction using multi-energy system matrices with a scintillator-based gamma camera for nuclear security applications.

The system response of a gamma camera is dependent on the photon energy, thus the energy-dependent response function needs to be considered to improve the quality and fidelity of reconstructed images for identifying radionuclides in security applications. In this study, two reconstruction strategies using the maximum-likelihood expectation maximization (MLEM) algorithm with the multi-energy system matrices calculated by Monte Carlo simulations are proposed. The difference between the two is in data acquisition; one uses the sum of all events into a single projection image while the other sorts them into separate energy windows. Various radiation images of gamma-ray sources were simulated with a Monte Carlo code, and an actual image was acquired with a gamma camera. Both simulation and experiment results demonstrated the feasibility of the presented multi-energy reconstruction strategies in the detection of orphan sources.

[1]  Matthew A. Blackston,et al.  Real time depth-of-interaction correction for coded-aperture, gamma-ray images , 2019, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.

[2]  Arun N. Netravali,et al.  Reconstruction filters in computer-graphics , 1988, SIGGRAPH.

[3]  Manhee Jeong,et al.  Comparison of gamma ray localization using system matrixes obtained by either MCNP simulations or ray-driven calculations for a coded-aperture imaging system , 2020 .

[4]  R. Narayan,et al.  Maximum Entropy Image Restoration in Astronomy , 1986 .

[5]  Jack G. M. FitzGerald,et al.  A Modulating Liquid Collimator for Coded Aperture Adaptive Imaging of Gamma-Rays , 2013, IEEE Transactions on Nuclear Science.

[6]  David Ramsden,et al.  The application of pinhole and coded aperture imaging in the nuclear environment , 1999 .

[7]  Peter Marleau,et al.  Demonstration of two-dimensional time-encoded imaging of fast neutrons , 2015 .

[8]  D. Lacour,et al.  Metrological characterization of the GAMPIX gamma camera , 2019, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.

[9]  K. Lange,et al.  EM reconstruction algorithms for emission and transmission tomography. , 1984, Journal of computer assisted tomography.

[10]  A. Dell'Acqua,et al.  Geant4 - A simulation toolkit , 2003 .

[11]  Jean-Marie Rocchisani,et al.  Coded aperture optimization using Monte Carlo simulations , 2010 .

[12]  Wolfgang Enghardt,et al.  Comparison of LSO and BGO block detectors for prompt gamma imaging in ion beam therapy , 2015 .

[13]  D. Loukas,et al.  Imaging of spatially extended hot spots with coded apertures for intra-operative nuclear medicine applications , 2017 .

[14]  E E Fenimore,et al.  New family of binary arrays for coded aperture imaging. , 1989, Applied optics.

[15]  I Buvat,et al.  Fully 3D Monte Carlo reconstruction in SPECT: a feasibility study , 2005, Physics in medicine and biology.

[16]  L. Shepp,et al.  A Statistical Model for Positron Emission Tomography , 1985 .

[17]  C. Mahe,et al.  Development of a portable gamma camera with coded aperture , 2006 .

[18]  Yi-Hwa Liu,et al.  Aperture collimation correction and maximum-likelihood image reconstruction for near-field coded aperture imaging of single photon emission computerized tomography , 2006, IEEE Transactions on Medical Imaging.

[19]  K. Ziock,et al.  Principles and applications of gamma-ray imaging for arms control , 2018 .

[20]  Stephane Normand,et al.  GAMPIX: A new gamma imaging system for radiological safety and Homeland Security Purposes , 2011, 2011 IEEE Nuclear Science Symposium Conference Record.

[21]  Le Gao,et al.  Reconstruction method for gamma-ray coded-aperture imaging based on convolutional neural network , 2019, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.

[22]  E. Caroli,et al.  Coded aperture imaging in X- and gamma-ray astronomy , 1987 .

[23]  Trevor J. Ponman,et al.  Reconstruction of images from a coded-aperture box camera , 1992 .

[24]  Vincent Breton,et al.  GATE (geant4 application for tomographic emission): a PET/SPECT general-purpose simulation platform , 2003 .