Feasibility of single-view coded source neutron transmission tomography

Abstract

In a simulation experiment, we study the feasibility of single-view coded source neutron transmission tomography for imaging water density in fuel cells at the NIST neutron imaging facility. In standard two-dimensional transmission tomography, one reconstructs a spatially varying attenuation image based on many projections or views of an object. Here, we consider the limiting case where only one view is available. Rather than parallel beam sources, the projection data are produced by multiple pinhole sources. For a high-count case where the object is near the sources and the object magnification is approximately 200, and attenuation varies very smoothly in the object, we demonstrate that a penalized maximum likelihood method yields a reconstruction of attenuation that has a fractional root-mean-square prediction error of 5.8%. We determine the regularization parameter in the penalized likelihood method using a statistical learning method called two-fold cross-validation. As the object-to-source distance increases and object magnification in the detector plane decreases, the quality of the reconstruction deteriorates. At the NIST neutron imaging facility, the object magnification in a single-view coded source neutron imaging experiment would be only about 4. Due to this low magnification, even for the favorable case considered where attenuation varies very smoothly and we observe high-count projection data, we conclude that single-view coded source neutron transmission tomography is not a promising method for quantifying the spatial distribution of water in a fuel cell. (Contributions by staff of NIST, an agency of the US Government, are not subject to copyright.)