Blind X-Ray CT Image Reconstruction From Polychromatic Poisson Measurements

Gu, Rentao; Dogandzic, A.

doi:10.1109/tci.2016.2523431

Cited by 14 publications

(12 citation statements)

References 36 publications

(63 reference statements)

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“…Application of advanced and complicated beam hardening correction (BHC) algorithms, such as the algorithms proposed by Kyriakou et al (2010) and Gu and Dogandžić (2016), is out of scope of this study; hence, a simple way of correcting beam hardening was adopted. According to the maximum and minimum void ratios (Table 1) and Eq.…”

Section: Calibration Of Ct Resultsmentioning

confidence: 99%

Centrifuge modelling of submarine landslides due to static liquefaction

Zhang¹,

Askarinejad²

2019

Landslides

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Sand erosion and scouring caused by waves and marine currents result in gradual increase of local seabed inclination and formation of slopes around hydraulic structures and offshore foundations. During this process, shear stresses in the soil body increase monotonically which may lead to static liquefaction and damage of the adjacent offshore infrastructure. This paper presents the details of a newly developed static liquefaction triggering actuator to be used at an enhanced gravity condition in a geotechnical centrifuge. This actuator simulates the steeping process of submarine sand layers due to scouring and enables the investigation of failure mechanisms in submerged slopes. The details of the centrifuge test setup designed and constructed to simulate the process of triggering static liquefaction in loose sand layers are presented. Furthermore, the performance of the novel integrated model preparation facility using sand fluidization is explained. The setup was used to conduct several centrifuge tests at four different slope steepening rates to investigate the slope steepening rate effects. Moreover, the effect of viscosity of the submerging pore fluid on the behaviour of the slopes at the onset of failure is investigated. The Coriolis effect on loose saturated sand samples during increase of g-level is examined as well. Results show that the built-up of pore pressure due to local shear deformations can be detected and considered as one of the triggering mechanisms of this kind of submarine slope instabilities.

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Section: Calibration Of Ct Resultsmentioning

confidence: 99%

Centrifuge modelling of submarine landslides due to static liquefaction

Zhang¹,

Askarinejad²

2019

Landslides

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“…The X-ray emitter of a computed tomography scanner emits a poly-energetic beam, [3]. Materials have different attenuation coefficients for each energy band, [4], so the beam incident on a receiver can be described as polychromatic, [5].…”

Section: Noisementioning

confidence: 99%

Low-Dose Computed Tomography Filtering Using Geodesic Distances

Góes

Mascarenhas

2020

Anais Estendidos Da Conference on Graphics, Patterns and Images (SIBRAPI Estendido 2020)

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Due to the concerns related to patient exposure to X-ray, the dosage used in computed tomography must be reduced (Low-dose Computed Tomography - LDCT). One of the effects of LDCT is the degradation in the quality of the final reconstructed image. In this work, we propose a method of filtering LDCT sinograms that are subject to signal-dependent Poisson noise. To filter this type of noise, we use a Bayesian approach, changing the Non-local Means (NLM) algorithm to use geodesic stochastic distances for Gamma distribution, the conjugate prior to Poisson, as a similarity metric between each projection point. Among the geodesic distances evaluated, we found a closed solution for the Shannon entropy for Gamma distributions. We compare our method with the following methods based on NLM: PoissonNLM, Stochastic Poisson NLM, Stochastic Gamma NLM and the original NLM after Anscombe transform. We also compare with BM3D after Anscombe transform. Comparisons are made on the final images reconstructed by the Filtered-Back Projection (FBP) and Projection onto Convex Sets (POCS) methods using the metrics PSNR and SSIM.

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“…As a consequence, the same object reacts differently when subjected to X-rays of different energy levels, generating unwanted artifacts in the reconstructed image. These defects can be avoided, but with the adoption of complex models as in [12,13,36] and at a high computational cost. This topic is complex and still subject to change because CT scanners using monoenergetic X-ray sources are beginning to emerge [37].…”

Section: Modeling the Objective Functionmentioning

confidence: 99%

A Soft-Threshold Filtering Approach for Tomography Reconstruction from a Limited Number of Projections with Bilateral Edge Preservation

Wirtti

Salles

2019

Sensors

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In X-ray tomography image reconstruction, one of the most successful approaches involves a statistical approach with l 2 norm for fidelity function and some regularization function with l p norm, 1 < p < 2 . Among them stands out, both for its results and the computational performance, a technique that involves the alternating minimization of an objective function with l 2 norm for fidelity and a regularization term that uses discrete gradient transform (DGT) sparse transformation minimized by total variation (TV). This work proposes an improvement to the reconstruction process by adding a bilateral edge-preserving (BEP) regularization term to the objective function. BEP is a noise reduction method and has the purpose of adaptively eliminating noise in the initial phase of reconstruction. The addition of BEP improves optimization of the fidelity term and, as a consequence, improves the result of DGT minimization by total variation. For reconstructions with a limited number of projections (low-dose reconstruction), the proposed method can achieve higher peak signal-to-noise ratio (PSNR) and structural similarity index measurement (SSIM) results because it can better control the noise in the initial processing phase.

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Blind X-Ray CT Image Reconstruction From Polychromatic Poisson Measurements

Cited by 14 publications

References 36 publications

Centrifuge modelling of submarine landslides due to static liquefaction

Centrifuge modelling of submarine landslides due to static liquefaction

Low-Dose Computed Tomography Filtering Using Geodesic Distances

A Soft-Threshold Filtering Approach for Tomography Reconstruction from a Limited Number of Projections with Bilateral Edge Preservation

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