MLEM Image Reconstruction Algorithm for Transmission Tomographic Gamma Scanning in Drummed Nuclear Wastes

Abstract

In this paper, 7 different samples and two radioactive isotopes ( 60 Co and 137 Cs) are used to fill a standard industrial waste bucket for simulating the real situation of drummed nuclear wastes. A transmission tomographic gamma scanning (TGS) measurement is carried out based on the TGS system independently developed by the project group for transmission image reconstruction. The data is processed by the MLEM iterative algorithm, it's able to reconstruct the actual distribution of inhomogeneous media within the drum and to correct attenuation coefficients values of media under particular emission energies. The results show: the MLEM iterative algorithm can reconstruct clear TGS transmission images with accurate resolution of different densities which accord with the actual distributions of inhomogeneous media within the drum; the quality of reconstructed images tend to improve with the increase of transmission energy; the corrected attenuation coefficients values of 72 voxels within the drum under emission energy:661.661keV, 1173.238keV and 1332.513keV are consistent with the reference values, which proves the validity of this method.