Improving image quality in fast, time-resolved micro-CT by weighted back projection

Heyndrickx, Marjolein; Bultreys, Tom; Goethals, Wannes; Hoorebeke, Luc Van; Boone, Matthieu

doi:10.1038/s41598-020-74827-x

Cited by 7 publications

(6 citation statements)

References 41 publications

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“…Despite our use of GPUs, there is certainly a speed‐up to be gained from optimizing the code toward high‐performance computing. Moreover, we also suspect that there could be considerable room for reducing the computation load by directing the reconstruction efforts to regions within the sample that de facto exhibit significant changes at the given time step (Heyndrickx et al., 2020). As briefly discussed in the Introduction, machine learning is under rapid development and will prove a highly important tool also for measuring and understanding transport in porous media in the coming years.…”

Section: Discussionmentioning

confidence: 99%

4D Imaging of Two‐Phase Flow in Porous Media Using Laboratory‐Based Micro‐Computed Tomography

Tekseth,

Breiby

2024

Water Resources Research

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Dynamic three‐dimensional computed tomography (CT) imaging of liquid transport in porous media has primarily been conducted at high brilliance synchrotrons thus allowing fast, sometimes sub‐second, temporal resolution to be obtained. University laboratory CT instruments lack the photon flux available at synchrotrons, limiting the obtainable spatiotemporal resolution. Here, we discuss our experiences with instrumentation and software methods to conduct time‐resolved micro‐computed tomography (4D‐CT) experiments of flow in porous media, based on a conventional CT instrument operated with a highly undersampled number of projections. An experimental stage outfitted with syringe pumps placed on a slip ring allowed two‐phase flow experiments to be carried out with continuous unidirectional rotation and without obstruction of the liquid supply lines. An iterative reconstruction algorithm based on a priori information was used to provide high image quality and ∼30 s time resolution despite the few and low‐exposed projections compared to standard protocols. The experimental technique was demonstrated with imbibition and drainage in glass bead‐pack and Bentheimer sandstone samples with sub‐minute temporal resolution, allowing the liquid configurations just before and after fast dynamic phenomena such as cooperative pore‐filling events and Haines jumps to be captured. Power law scaling exponents for burst volumes associated with imbibition and drainage were estimated and compared with the literature. That 4D‐CT experiments can be carried out using conventional CT instruments to challenge contemporary permeability models is of high importance for many geo‐, bio‐ and environmental physics challenges.

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Section: Discussionmentioning

confidence: 99%

4D Imaging of Two‐Phase Flow in Porous Media Using Laboratory‐Based Micro‐Computed Tomography

Tekseth,

Breiby

2024

Water Resources Research

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“…This way, the particle positions were calculated for each radiograph time step in 7 consecutive CT scans of 360 and 700 radiographs each, matching the experimental acquisition. Each of these radiographs was then calculated by raytracing using the in-house developed CTRex code (Heyndrickx et al, 2020;Schryver et al, 2018). Poisson noise was added on the radiographs to match the noise level in the experiment.…”

Section: Simulated Ct Data Sets For Methods Validationmentioning

confidence: 99%

X-ray tomographic micro-particle velocimetry in porous media

et al. 2022

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Fluid flow through intricate confining geometries often exhibits complex behaviors, certainly in porous materials, e.g., in groundwater flows or the operation of filtration devices and porous catalysts. However, it has remained extremely challenging to measure 3D flow fields in such micrometer-scale geometries. Here, we introduce a new 3D velocimetry approach for optically opaque porous materials, based on time-resolved x-ray micro-computed tomography (CT). We imaged the movement of x-ray tracing micro-particles in creeping flows through the pores of a sandpack and a porous filter, using laboratory-based CT at frame rates of tens of seconds and voxel sizes of 12 μm. For both experiments, fully three-dimensional velocity fields were determined based on thousands of individual particle trajectories, showing a good match to computational fluid dynamics simulations. Error analysis was performed by investigating a realistic simulation of the experiments. The method has the potential to measure complex, unsteady 3D flows in porous media and other intricate microscopic geometries. This could cause a breakthrough in the study of fluid dynamics in a range of scientific and industrial application fields.

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“…All high-speed/in-situ publications included in figure 13 use FBP for fair comparative purposes, but there were 9 out of the 596 studies from the literature search that used iterative reconstruction methods that typically require a lower numbers of projections [55,[110][111][112][113][114][115][116][117]. For example Myers et al [113] experiments with two-phase fluid flow, used an iterative algorithm that exploits the a priori knowledge of the sample.…”

Section: Number Of Projectionsmentioning

confidence: 99%

Review of high-speed imaging with lab-based x-ray computed tomography

Zwanenburg

Williams

Warnett

2021

Meas. Sci. Technol.

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X-ray computed tomography (CT) is frequently used for non-destructive testing with many applications in a wide range of scientific research areas. The difference in imaging speeds between synchrotron and lab-based scanning has reduced as the capabilities of commercially available CT systems have improved, but there is still a need for faster lab-based CT both in industry and academia. In industry high-speed CT is desirable for inline high-throughput CT at a higher resolution than currently possible which would save both time and money. In academia it would allow for the imaging of faster phenomena, particularly dynamic in-situ testing, in a lab-based setting that is more accessible than synchrotron facilities. This review will specifically highlight what steps can be taken by general users to optimise scan speed with current equipment and the challenges to still overcome. A critical evaluation of acquisition parameters across recent high-speed studies by commercial machine users is presented, indicating some areas that could benefit from the methodology described. The greatest impacts can be achieved by maximising spot size without notably increasing unsharpness, and using a lower number of projections than suggested by the Nyquist criterion where the anecdotal evidence presented suggests usable results are still achievable.

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Improving image quality in fast, time-resolved micro-CT by weighted back projection

Cited by 7 publications

References 41 publications

4D Imaging of Two‐Phase Flow in Porous Media Using Laboratory‐Based Micro‐Computed Tomography

4D Imaging of Two‐Phase Flow in Porous Media Using Laboratory‐Based Micro‐Computed Tomography

X-ray tomographic micro-particle velocimetry in porous media

Review of high-speed imaging with lab-based x-ray computed tomography

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