Radiogram enhancement and linearization using the beam hardening correction method

Vavřı́k, Daniel; Jakůbek, J.

doi:10.1016/j.nima.2009.03.156

Cited by 38 publications

(29 citation statements)

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“…Linearization of the attenuation range (beam hardening correction) was applied to all the data to reduce the noise and improve the contrast in individual projections. 11 Due to high porosity of the samples and the small thickness of the structural elements (approximately 30 μm), the cone-beam reconstruction algorithm 12 was used to eliminate the distortion of the reconstructed data caused by the divergent nature of the X-ray beam.…”

Section: Radiographical Imagingmentioning

confidence: 99%

Time-lapse micro-tomography analysis of the deformation response of a gellan-gum-based scaffold

Kytýř¹,

Fenclová²,

Zlámal³

et al. 2017

Mater. Tehnol.

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The presented work is aimed at a demonstration of modern radiological methods for an investigation of the deformation behaviour of bone scaffolds. Bone scaffold is an artificial structure used for the repairs of trabecular bones damaged by injuries or degenerative diseases. In bone-tissue engineering a proper description of its deformation behaviour is one of the most important characteristics for an assessment of the biocompatibility and bone-integration characteristics of the proposed structure intended to be used as a bone scaffold. According to recent studies bioactive-glass-reinforced gellan-gum (GG-BAG) is a promising material for bone-scaffold production. However, its low specific stiffness and simultaneous low attenuation to X-rays makes both the mechanical and imaging parts of the deformation experiments difficult. As a result a state-of-the-art experimental setup composed of high-precision micro-loading apparatus designed for the X-ray observation of deformation processes and an advanced radiographical device is required for such experiments. Furthermore, the radiographical device has to utilize highly sensitive detectors and corresponding radiation sources with appropriate beam characteristics that provide a high signal-to-noise ratio (SNR) during all the measurements. High-resolution time-lapse micro-focus X-ray computed tomography (micro CT) under loading in three different imaging modes was performed to obtain a precise structural and mechanical description of the observed deforming GG-BAG scaffolds. The digital volumetric correlation (DVC) method was applied on reconstructed data from micro CT measurements to evaluate not only the effective mechanical characteristics but also to enable a detailed inspection of the specimens' internal structure, particularly the deformation modes of the individual struts and joints. The calculated volumetric strain fields demonstrate the suitability of such experimental methodology and devices for the assessment of both the microscopic and macroscopic characteristics of the investigated complex GG-BAG microarchitectures. Keywords: bone scaffold, gellan gum, time-lapse micro CT, digital volume correlation Predstavljeno delo je namenjeno prikazu sodobnih radiolo{kih metod za preiskave obna{anja deformacije kostno-regenerativnih celi~nih ogrodij. Tak{no celi~no ogrodje je tridimenzionalna umetna struktura, ki se uporablja za regeneracijo trabekularne kosti ob po{kodbah ali pri degenerativnih boleznih. Pravilen opis obna{anja ogrodja ob deformaciji je eden od pomembnej{ih faktorjev za dolo~itev biokompatibilnosti ogrodja, in kako se bo to ogrodje vklju~ilo v tkivo, v katerega je vstavljeno. Glede na nedavne {tudije, je kompozit bioaktivno steklo -gelanski gumi (GG-BAG), obetaven material za pripravo kostno-regenerativnih celi~nih ogrodij. Zaradi nizke specifi~ne togosti materiala in slabljenja rentgenskih`arkov, je ote`eno zaznavanje deformacije, tako mehansko kot tudi z rentgenskimi`arki. Zaradi zahtevnosti sistema je za tako preizku{anje potrebna posebna naprava, ses...

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Section: Radiographical Imagingmentioning

confidence: 99%

Time-lapse micro-tomography analysis of the deformation response of a gellan-gum-based scaffold

Kytýř¹,

Fenclová²,

Zlámal³

et al. 2017

Mater. Tehnol.

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show abstract

“…10 Linearization of the attenuation range (a beamhardening correction) was applied to reduce the noise and improve the contrast of individual projections. 11 Due to a high porosity of the samples and a small thickness of the trabeculae (approximately 200 μm), the cone-beam reconstruction algorithm 12 was used to eliminate the distortion of the reconstructed data caused by the divergent nature of the X-ray beam.…”

Section: Microtomography Measurementmentioning

confidence: 99%

Deformation behaviour of a natural-shaped bone scaffold

Kytýř¹,

Doktor²,

Jiroušek³

et al. 2016

Mater. Tehnol.

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The study aims at mechanical testing of an artificial bone structure in the form of a scaffold for the application in the repairs of trabecular bones after wounds or degenerative diseases. Such artificial construct has to conform to many requirements including biocompatibility, permeability properties and bone-integration characteristics. Recently, self-degradable bone scaffolds suitable for natural-bone-tissue ingrowth optimized with respect to mechanical properties and body-fluid flow have been considered as an alternative to allografts and autografts. Here, an analysis of deformation behaviour of a scaffold with a morphology identical to the natural bone is the first step in this task. In this work, the geometry and morphology of scaffold specimens produced with direct 3D printing were based on a 3D model derived from the X-ray-computed micro-tomography measurement of a real trabecular bone. The geometrical model was upscaled four times in order to achieve the optimum ratio between its resolution and the resolution of the 3D printer. For its biocompatibility and self-degradability, polylactic acid was used as the printing material. The mechanical characteristics were obtained from a series of uniaxial compression tests, with an optical evaluation of the strain field on the surfaces of the specimens. The acquired stress-strain curves were compared with the characteristics of a real trabecular bone obtained with time-lapse microtomography measurements, evaluated with the digital volumetric correlation method. The results show good correspondence of the stiffness values for both the natural and artificial bone specimens. Keywords: bone scaffold, polylactic acid, additive manufacturing, compression loading, microtomography Namen {tudije je mehansko preizku{anje umetnega ogrodja kosti za obnovo trabekularnih kosti po po{kodbah ali degenerativnih boleznih. Tako umetno ogrodje mora ustrezati mnogim zahtevam, kot so biokompatibilnost, prepustnost in mo`nost vra{~anja kostnega tkiva. Samo razgradljivo ogrodje kosti, primerno za naravno vra{~anje kostnega tkiva, optimirano glede na mehanske lastnosti in toka telesnih teko~in, je bilo prou~evano kot nadomestek za presajanje tujega ali lastnega tkiva. Prvi korak pri tej nalogi je analiza obna{anja ogrodja, z morfologijo podobno naravni kosti. V tem delu je bila geometrija in morfologija vzor~nega ogrodja izdelana z neposrednim tridimenzionalnim tiskanjem, na osnovi tridimenzionalnega modela, dobljenega z meritvami s pomo~jo rentgenske tomografije realne trabekularne kosti. Geometrijski model je bil pove~an {tirikrat, da bi dobili optimalno razmerje med njegovo resolucijo in resolucijo tridimenzionalnega tiskalnika. Za biokompatibilnost in sâmo razgradljivost, je bila za tiskanje uporabljena polilakti~na kislina. Mehanske zna~ilnosti so bile dobljene z vrsto enoosnih tla~nih preizkusov in z opti~no oceno napetostnega polja na povr{ini vzorcev. Pridobljene krivulje napetost-raztezek so bile primerjane z zna~ilnostmi realne trabekularne kosti, ki so bile dobljene z zaporedn...

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“…The application of the Pixelman software furthermore enables also direct application of previously developed tools, e.g. for beam hardening effect correction [15] and tomographic reconstruction.…”

Section: Redesigned Systemmentioning

confidence: 99%

X-ray micro-CT scanner for small animal imaging based on Timepix detector technology

Dudák

Žemlička

Krejci

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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Radiogram enhancement and linearization using the beam hardening correction method

Cited by 38 publications

References 1 publication

Time-lapse micro-tomography analysis of the deformation response of a gellan-gum-based scaffold

Time-lapse micro-tomography analysis of the deformation response of a gellan-gum-based scaffold

Deformation behaviour of a natural-shaped bone scaffold

X-ray micro-CT scanner for small animal imaging based on Timepix detector technology

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