Crystalline phase discriminating neutron tomography using advanced reconstruction methods

Evelina Ametova, Genoveva Burca, Suren Chilingaryan, Gemma Fardell, Jakob Jorgensen, Evangelos Papoutsellis, Edoardo Pasca, Ryan Warr, Martin Turner, William Lionheart, Philip Withers

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Abstract

Time-of-flight neutron imaging offers complementary attenuation contrast to X-ray computed tomography (CT), coupled with the ability to extract additional information from the variation in attenuation as a function of neutron energy (time of flight) at every point (voxel) in the image. In particular, Bragg edge positions provide crystallographic information and therefore enable the identification of crystalline phases directly. Here we demonstrate Bragg edge tomography with high spatial and spectral resolution. We propose a new iterative tomographic reconstruction method with a tailored regularisation term to achieve high quality reconstruction from low-count data, where conventional filtered back-projection (FBP) fails. The regularisation acts in a separated mode for spatial and spectral dimensions and favours characteristic piece-wise constant and piece-wise smooth behaviour in the respective dimensions. The proposed method is compared against FBP and a state-of-the-art regulariser for multi-channel tomography on a multi-material phantom. The proposed new regulariser which accommodates specific image properties outperforms both conventional and state-of-the-art methods and therefore facilitates Bragg edge fitting at the voxel level. The proposed method requires significantly shorter exposure to retrieve features of interest. This in turn facilitates more efficient usage of expensive neutron beamline time and enables the full utilisation of state-of-the-art high resolution detectors.
Original languageEnglish
Article number325502
JournalJournal of Physics D: Applied Physics
Volume54
DOIs
Publication statusPublished - 8 Jun 2021

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