Enyu Guo

Temporal sparsity exploiting nonlocal regularization for 4D computed tomography reconstruction.

X-ray imaging applications in medical and material sciences are frequently limited by the number of tomographic projections collected. The inversion of the limited projection data is an ill-posed problem and needs regularization. Traditional spatial regularization is not well adapted to the dynamic nature of time-lapse tomography since it discards the redundancy of the temporal information. In this paper, we propose a novel iterative reconstruction algorithm with a nonlocal regularization term to account for time-evolving datasets. The aim of the proposed nonlocal penalty is to collect the maximum relevant information in the spatial and temporal domains. With the proposed sparsity seeking approach in the temporal space, the computational complexity of the classical nonlocal regularizer is substantially reduced (at least by one order of magnitude). The presented reconstruction method can be directly applied to various big data 4D (x, y, z+time) tomographic experiments in many fields. We apply the proposed technique to modelled data and to real dynamic X-ray microtomography (XMT) data of high resolution. Compared to the classical spatio-temporal nonlocal regularization approach, the proposed method delivers reconstructed images of improved resolution and higher contrast while remaining significantly less computationally demanding.

Anomalous α-Mg Dendrite Growth During Directional Solidification of a Mg-Zn Alloy

Dendritic morphology was investigated in a directionally solidified magnesium-zinc alloy using synchrotron X-ray tomography and electron backscattered diffraction. Unexpectedly, primary dendrites grew along

A 4-D dataset for validation of crystal growth in a complex three-phase material, ice cream

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Fast synchrotron X-ray tomographic quantification of dendrite evolution during the solidification of Mg-Sn alloys

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Model-based iterative reconstruction using higher-order regularization of dynamic synchrotron data

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The Use of In Situ X-ray Imaging Methods in the Research and Development of Magnesium-Based Grain-Refined and Nanocomposite Materials

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