Image reconstruction techniques using projection data from transmission method

This paper gives a brief description of a filter back projection (FBP) and Algebraic Reconstruction techniques (ART), which are used for reconstruction of projected data obtained from transmission measurements. Both techniques are tested by reconstructing a simulated object, showing that the FBP technique yields images with better resolution and higher contrast, thus resulting in more accurate information than obtained by ART. Experimental data has been obtained for unheated and heated ordinary and heavy concrete samples by transmission measurements using a thermal neutron beam emitted from the spallation neutron source SINQ at PSI, Switzerland. The data are used to reconstruct the images of the examined samples using the FBP technique with different filter functions, including the Shepp Logan filter function produces images of higher contract, more smoothing and slightly better resolution than those obtained using the absolute filter function. Based on these images the samples were investigated for water content, cracks, homogeneity, etc. (C) 2004 Elsevier Ltd. All rights reserved.