Process Control For Composites Using Computed Tomography

Engler, P.; Friedman, W. D.; Santana, M. W.; Chi, Frank

doi:10.1557/proc-217-123

Cited by 7 publications

(8 citation statements)

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“…Hawkes and Jackson (1980) showed that the linear attenuation coefficient cannot be factorized into separable functions of E and Z and encouraged the pursuit of energy and atomic number independent parameters. Use of the effective atomic number and effective electron density has been quite common in the past (Rutherford et al 1976, Isherwood et al 1977, White 1977, Brownell 1984, Engler and Friedman 1990.…”

Section: Semi-empirical Parametrizationsmentioning

confidence: 99%

“…Mass density can be measured using single photon absorptiometry and dual energy x-ray absorption (DEXA) with reference to a calibration phantom. In dual energy CT, measurements taken at two x-ray energies can provide sufficient information to resolve the density and compositional contributions, given that the two energies are sufficiently different, that attenuation at one energy is due primarily to photoelectric absorption and attenuation at the second energy is due primarily to Compton scattering (Engler andFriedman 1990, Alvarez andMacovski 1976). These results are characterized by an effective atomic number and effective mass electron density.…”

Section: Photon Absorptiometry and Dual Energy Ctmentioning

confidence: 99%

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Extracting material parameters from x-ray attenuation: a CT feasibility study using kilovoltage synchrotron x-rays incident upon low atomic number absorbers

et al. 2003

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The work reported here is a feasibility study of the extraction of material parameters from measurements of the linear x-ray attenuation coefficient of low atomic number absorbers. Computed tomography (CT) scans of small samples containing several liquids and solids were carried out with synchrotron radiation at the Australian National Beamline Facility (BL 20B) in Japan. Average values of the x-ray linear attenuation coefficient were extracted for each material for x-ray energies ranging from 11 keV to 20.5 keV. The electron density was estimated by applying results derived from a parametrization of the x-ray linear attenuation coefficient first developed by Jackson and Hawkes and extended for this work. Average estimates for the electron density of triethanolamine and acetic acid were made to within +5.3% of the actual value. Other materials examined included furfuraldehyde, perspex and teflon, for which average estimates of the electron density were less than 10% in excess of the calculated value.

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Section: Semi-empirical Parametrizationsmentioning

confidence: 99%

Section: Photon Absorptiometry and Dual Energy Ctmentioning

confidence: 99%

Extracting material parameters from x-ray attenuation: a CT feasibility study using kilovoltage synchrotron x-rays incident upon low atomic number absorbers

et al. 2003

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“…In recent years there has been substantial interest in dual-or multienergy CT systems, in which measurements are made either with differing x-ray energy spectra [1,2], or using energy-resolving detectors [3]. By exploiting the energy-dependence of x-ray attenuation, these systems can provide additional, valuable information regarding object material properties [4,5].…”

Section: Inverse Problemsmentioning

confidence: 99%

Stabilizing dual-energy x-ray computed tomography reconstructions using patch-based regularization

Tracey¹,

Miller²

2015

Inverse Problems

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Recent years have seen growing interest in exploiting dual-and multi-energy measurements in computed tomography (CT) in order to characterize material properties as well as object shape. Materials characterization is performed by decomposing the scene into constitutive basis functions, such as Compton scatter and photoelectric absorption functions. While well motivated physically, the joint recovery of the spatial distribution of photoelectric and Compton properties is severely complicated by the fact that the data are several orders of magnitude more sensitive to Compton scatter coefficients than to photoelectric absorption, so small errors in Compton estimates can create large artifacts in the photoelectric estimate. To address these issues, we propose a model-based iterative approach which uses patch-based regularization terms to stabilize inversion of photoelectric coefficients, and solve the resulting problem though use of computationally attractive Alternating Direction Method of Multipliers (ADMM) solution techniques. Using simulations and experimental data acquired on a commercial scanner, we demonstrate that the proposed processing can lead to more stable material property estimates which should aid materials characterization in future dual-and multi-energy CT systems.

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“…Compared to conventional CT based on the ideal case, it takes into account the polychromaticity of x-ray beam and the energy-dependence of attenuation coefficient in the imaging model, and is able to obtain more properties of the scanned object, which makes it a potential advantage in substance identification. Therefore, it has a wide range of applications in both medical and industrial fields, such as soft tissue discrimination (Zachrisson et al 2010), bone mineral analysis (Genant and Boyd 1977), security inspection (Roder 1979, nondestructive testing (Engler and Friedman 1990), etc.…”

Section: Introductionmentioning

confidence: 99%

A model-based direct inversion network (MDIN) for dual spectral computed tomography

Zhou,

Zhang,

Zhao

et al. 2024

Phys. Med. Biol.

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Dual spectral computed tomography (DSCT) is a very challenging problem in the field of imaging. Due to the nonlinearity of its mathematical model, the images reconstructed by the conventional CT usually suffer from the beam hardening artifacts. Additionally, several existing DSCT methods rely heavily on the information of the spectra, which is often not readily available in applications. To address this problem, in this study, we propose a Model-based Direct Inversion Network (MDIN) for DSCT, which can directly predict the basis material images from the collected polychromatic projections. The all operations are performed in the network, requiringneither the conventional algorithms nor the information of the spectra. It can be viewed as an approximation to the inverse procedure of DSCT imaging model. The MDIN is composed of projection pre-decomposition module (PD-module), domain transformation layer (DT-layer), and image post-decomposition module (ID-module). The PD-module first performs the pre-decomposition on the polychromatic projections that consists of a series of stacked one-dimensional convolution layers. The DT-layer is designed to obtain the preliminary decomposed results, which has the characteristics of sparsely connected and learnable parameters. And the ID-module uses a deep neural network (DNN) to further decompose the reconstructed results of the DT-layer so as to achieve higher-quality basis material images. Numerical experiments demonstrate that the proposed MDIN has significant advantages in substance decomposition,artifact reduction and noise suppression compared to other methods in the DSCT reconstruction.

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Process Control For Composites Using Computed Tomography

Cited by 7 publications

References 0 publications

Extracting material parameters from x-ray attenuation: a CT feasibility study using kilovoltage synchrotron x-rays incident upon low atomic number absorbers

Extracting material parameters from x-ray attenuation: a CT feasibility study using kilovoltage synchrotron x-rays incident upon low atomic number absorbers

Stabilizing dual-energy x-ray computed tomography reconstructions using patch-based regularization

A model-based direct inversion network (MDIN) for dual spectral computed tomography

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