Multi-species beam hardening calibration device for x-ray microtomography

Evershed, Anthony N. Z.; Mills, David; Davis, Graham

doi:10.1117/12.928933

Cited by 13 publications

(5 citation statements)

References 18 publications

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“…For these reasons, scanning was briefly interrupted approximately every 24 hours to reduce the filament current to the minimum level that provided an acceptable focus and to refresh the reservoir; this took approximately 10 minutes. A calibration carousel was also scanned at the end of each 24-hour period [15]. The voxel size was set to 30 µm, with 927 projections around 360⁰, taking 2.6 hours, allowing 9 scans per day.…”

Section: Methodsmentioning

confidence: 99%

Real-time observations of tooth demineralization in 3 dimensions using X-ray microtomography

Davis

Mills

Anderson

2018

Journal of Dentistry

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Section: Methodsmentioning

confidence: 99%

Real-time observations of tooth demineralization in 3 dimensions using X-ray microtomography

Davis

Mills

Anderson

2018

Journal of Dentistry

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“…Immediately following the scan, a multi‐element calibration carousel (Evershed et al. ) was scanned to characterise the X‐ray spectrum. As direct measurement of the X‐ray spectrum is almost impossible (with the degree of accuracy required), a modelled estimate of the spectrum was made.…”

Section: Methodsmentioning

confidence: 99%

Body wall structure in the starfish Asterias rubens

et al. 2017

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The body wall of starfish is composed of magnesium calcite ossicles connected by collagenous tissue and muscles and it exhibits remarkable variability in stiffness, which is attributed to the mechanical mutability of the collagenous component. Using the common European starfish Asterias rubens as an experimental animal, here we have employed a variety of techniques to gain new insights into the structure of the starfish body wall. The structure and organisation of muscular and collagenous components of the body wall were analysed using trichrome staining. The muscle system comprises interossicular muscles as well as muscle strands that connect ossicles with the circular muscle layer of the coelomic lining. The collagenous tissue surrounding the ossicle network contains collagen fibres that form loop‐shaped straps that wrap around calcite struts near to the surface of ossicles. The 3D architecture of the calcareous endoskeleton was visualised for the first time using X‐ray microtomography, revealing the shapes and interactions of different ossicle types. Furthermore, analysis of the anatomical organisation of the ossicles indicates how changes in body shape may be achieved by local contraction/relaxation of interossicular muscles. Scanning synchrotron small‐angle X‐ray diffraction (SAXD) scans of the starfish aboral body wall and ambulacrum were used to study the collagenous tissue component at the fibrillar level. Collagen fibrils in aboral body wall were found to exhibit variable degrees of alignment, with high levels of alignment probably corresponding to regions where collagenous tissue is under tension. Collagen fibrils in the ambulacrum had a uniformly low degree of orientation, attributed to macrocrimp of the fibrils and the presence of slanted as well as horizontal fibrils connecting antimeric ambulacral ossicles. Body wall collagen fibril D‐period lengths were similar to previously reported mammalian D‐periods, but were significantly different between the aboral and ambulacral samples. The overlap/D‐period length ratio within fibrils was higher than reported for mammalian tissues. Collectively, the data reported here provide new insights into the anatomy of the body wall in A. rubens and a foundation for further studies investigating the structural basis of the mechanical properties of echinoderm body wall tissue composites.

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“…For multi-material objects, this calibration, with additional Segmentation and estimation of the path-length, is required for each material, since they all have unique attenuation-distance curves [17]. For two materials, this can be avoided by assuming the lower attenuating material has zero attenuation [18]. Nevertheless, it is common to choose a single curve to correct the entire dataset even if the correction is only approximate (e.g.…”

Section: Introductionmentioning

confidence: 99%

X-ray attenuation models to account for beam hardening in computed tomography

et al. 2020

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We introduce a beam-hardening correction method for lab-based X-ray computed tomography (CT) by modifying existing iterative tomographic reconstruction algorithms. Our method simplifies the standard Alvarez-Macovski X-ray attenuation model (Physics in Medicine & Biology, 5, 733 [1976]) and is compatible with conventional (i.e. single-spectrum) CT scans. The sole modification involves a polychromatic projection operation which is equivalent to applying a weighting that more closely matches the attenuation of polychromatic X-rays. Practicality is a priority, so we only require information about the X-ray spectrum and some constants relating to material properties. No other changes to the experimental setup or the iterative algorithms are necessary. Using recontructions of simulations and several large experimental datasets, we show that this method is able to remove or reduce cupping, streaking, and other artefacts from X-ray beam hardening and improve the self-consistency of projected attenuation in CT. When the assumptions made in the simplifications are valid, the reconstructed tomogram can even be quantitative.

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Multi-species beam hardening calibration device for x-ray microtomography

Cited by 13 publications

References 18 publications

Real-time observations of tooth demineralization in 3 dimensions using X-ray microtomography

Real-time observations of tooth demineralization in 3 dimensions using X-ray microtomography

Body wall structure in the starfish Asterias rubens

X-ray attenuation models to account for beam hardening in computed tomography

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