Journal ArticleDOI
Penalized-likelihood image reconstruction for x-ray fluorescence computed tomography
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TLDR
A penalized-likelihood image reconstruction strategy that alternates between updating the distribution of a given element and updating the attenuation map for that element's fluorescence X-rays and is guaranteed to increase the penalized likelihood at each iteration.Abstract:
X-ray fluorescence computed tomography (XFCT) allows for the reconstruction of the distribution of elements within a sample from measurements of fluorescence x rays produced by irradiation of the sample with monochromatic synchrotron radiation. XFCT is not a transmission tomography modality, but rather a stimulated emission tomography modality; thus correction for attenuation of the incident and fluorescence photons is essential if accurate images are to be obtained. This is challenging because the attenuation map is, in general, known only at the stimulating beam energy and not at the various fluorescence energies of interest. We make use of empirically fitted analytic expressions for x-ray attenuation coefficients to express the unknown attenuation maps as linear combinations of known quantities and the unknown elemental concentrations of interest. We then develop an iterative image reconstruction algorithm based on penalized-likelihood methods that have been developed for medical emission tomography. Studies with numerical phantoms indicate that the approach is able to produce qualitatively and quantitatively accurate reconstructed images even in the face of severe attenuation. We also apply the method to real synchrotron-acquired data and demonstrate a marked improvement in image quality relative to filtered backprojection reconstruction.read more
Citations
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Proceedings ArticleDOI
Alternating update penalized-likelihood image reconstruction for x-ray fluorescence computed tomography
TL;DR: In this paper, an iterative algorithm that is guaranteed to increase a predefined objective function at each iteration is presented. But the objective function does not necessarily correspond to the maximization of the predefined penalized-likelihood objective function.
Journal ArticleDOI
On the Inversion of the xfct Radon Transform
TL;DR: In this paper, the spectral analysis of a particular partial differential equation yields the inversion formula for the problem of computerized emission tomography, and a similar analysis can be made for the case of X-ray fluorescence tomography.
Journal ArticleDOI
Region of Interest Reconstruction in X-Ray Fluorescence Computed Tomography for Negligible Attenuation
TL;DR: When attenuation is negligible, recent developments in tomographic reconstruction theory can be used to reduce the scanning effort required to reconstruct regions of interest within the slice and provides a backprojection-filtration reconstruction algorithm that averts the truncation artifacts that typically plague filtered backprojections from truncated data.
Journal ArticleDOI
Three-dimensional imaging of grain boundaries via quantitative fluorescence X-ray tomography analysis
Mingyuan Ge,Xiaojing Huang,Hanfei Yan,Doga Gursoy,Yuqing Meng,Jiayong Zhang,Sanjit Ghose,Wilson K. S. Chiu,Kyle S. Brinkman,Yong S. Chu +9 more
TL;DR: In this article , a three-dimensional visualization of material composition within multiple grains and across complex networks of grain boundaries at nanoscales is presented to provide new insight into the structure evolution and emerging functional properties of the material for diverse applications.
Book ChapterDOI
Compact micro-CT/micro-XRF system for non-destructive 3D analysis of internal chemical composition
A. Sasov,X. Liu,D. Rushmer +2 more
TL;DR: In this article, a dual-modality X-ray microfluorescence (micro-XRF) system was developed for non-destructive analysis of internal local chemical composition.
References
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Penalized weighted least-squares image reconstruction for positron emission tomography
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