|
|
CT X-ray quantitative evaluation
Novotný, Lukáš ; Malínský, Miloš (referee) ; Drastich, Aleš (advisor)
X-Ray Computed Tomography is irreplaceable medical imaging system. Quantitative evaluation is day to day routine used for clean run of this imaging system. The master’s thesis is focused on quantitative evaluation of first and third generation X-Ray CT. First of all is about subjective and objective evaluation of space and energetic resolution. Space resolution is evaluated in space and frequency domain. Energetic resolution is represent by low contrast resolution method. Application “Kvantitativní hodnocení kvality CT RTG zobrazení” created for this thesis is used for creation of reconstruction image and quantitative evaluation. This application was created with consideration of its usage in subjects about image processing. The master’s thesis contains results of quantitative evaluation X-Ray CT created with this application and proposal of lab work.
|
|
|
Scientific report. X-ray tomography of a steel weld
Vopálenský, Michal
X-ray computed tomography was used for visualization of the contact areas in a welded steel joint. The purpose of the tomography was to inspect the joint and analyse possible causes of cracks. The used method proved itself as a suitable one, since the crack was clearly visible on the reconstructed virtual model of the measured part.
|
|
|
Fast continuous in-situ XCT of additively manufactured carbon fiber reinforced tensile test specimens
Glinz, J. ; Maurer, J. ; Holzleitner, M. ; Pace, F. ; Stamopoulos, A. ; Vopálenský, Michal ; Kumpová, Ivana ; Eckl, M. ; Kastner, J. ; Senck, S.
The reinforcement of fused filament fabricated (FFF) components with continuous fibers allows for high versatility in the design of mechanical properties for a specific application’s needs. However, the bonding quality between continuous fibers and the FFF matrix material has high impact on the overall performance of the composite. In a recent study [1], additively manufactured (AM) continuous fiber reinforced tensile test specimens have been investigated regarding the effect of amount and material of the embedded continuous fibers on tensile strength and AM build quality. During these tensile tests, a sudden reduction in tensile stress, which most likely was not related to actual rupture of continuous fibers, was noticeable. Since X-ray computed tomography (XCT) scans were performed only prior to and after the tensile testing, a detailed investigation on the origin of these drops in tensile stress was not possible. Within this work, we will expand upon these findings and present results of fast on-the-fly in-situ investigations performed on continuous carbon fiber reinforced specimens of the same AM build. During these investigations, specimens are loaded under the same conditions while fast XCT scans, with a total scan time of 12 seconds each, were performed consecutively. The resulting three-dimensional image data reveals internal meso- and macro-structural changes over time/strain to find the cause of the aforementioned reduction in tensile stress.
|
|
|
Tomographic investigation of the sandstone fracture toughness
Vavřík, Daniel ; Beneš, Pavel ; Fíla, Tomáš ; Koudelka_ml., Petr ; Kumpová, Ivana ; Vavro, Martin
It is well known that the measured values of the fracture toughness of quasi brittle materials are influenced by material heterogeneity, dimensions, boundary conditions, and unequal tension and compression properties. Standard testing methods supposing isotropic material, in contrary the quasi-brittle materials differ from this theoretical expectation, therefore this approach may fail. The authors present Local Fracture Toughness Testing (LFTT) method to overcome this obstacle. LFFT based on a complex methodology using a series of tomographic reconstructions recorded during specimen loading is calculated independently of the outside boundary conditions.
|
|
|
Determination of device geometrical misalignments influence on dimensional measurements in X-ray microcomputed tomography
Blažek, Pavel ; Klapetek, Petr (referee) ; Zikmund, Tomáš (advisor)
Tato práce se zabývá geometrickými nepřesnostmi v geometrii rentgenového počítačového tomografu (CT přístroj). Především jejich vlivem na výsledky metrologických měření a metodami kterými lze tyto negativní efekty eliminovat. V práci jsou prezentovány výsledky simulací CT měření v softwaru aRTist při kterých byli nastavovány nepřesnosti v pozici detektoru a osy rotace vzorku. Ukazuje se tak, které geometrické faktory mají na měření největší vliv. Praktická část se pak zabývá CT přístrojem HeliScan, který využívá unikátní rekonstrukční algoritmus k eliminaci geometrických nepřesností. Jsou vyvinuty referenční objekty (pláty s rubínovými kuličkami a zirkonová koule), které splňují požadavky normy VDI/VDE 2630 1.3. na testování metrologických schopností přístroje. Objekty vhodné pro měření ve větším zorném polem byly vyrobeny, zkalibrovány a otestovány v CT měření.
|
|
|
Analysis of the porosity of a plaster cast, based on tomography data. Pilot measurement for the feasibility verification of the method for analyses of cast sculptures
Kumpová, Ivana ; Vopálenský, Michal
The aim of the tomographical research was the verification of the feasibility of the X-ray tomography for the qualitative description of the internal structure of the cast sculptures (damage, former restoration evidence etc.) and also for the characterization of the way and direction of the plaster pouring. There is a hypothesis that in the cast piece, the non-uniform distribution of pores as for the size (volume) along the vertical direction should be observable. The deeper in the piece, the higher amount of smaller pores and lower amount of bigger pores is expected. As well, lower porosity, i.e., ratio of the volume of the pores and the entire investigated volume, is expected deeper in the sample. The distribution of the pores could indicate, how the sculpture was made, in particular, where were the pouring holes and how many, what was the material flux like and how did it mixture. The method was verified on a specimen and the indicated hypotheses were only partly confirmed.
|
|
|
Region of interest tomography
Vopálenský, Michal ; Kumpová, Ivana
During standard tomographic process, the acquisition of tomographic data (projections) is performed with geometric adjustment of the tomographic assembly ensuring that the projection of the entire width of the examined object fits onto the detector during the full object rotation. Because of the limited width of the detector, this approach has a limited maximum achievable resolution for the given specimen diameter. It is possible to make higher magnification, but then the projections do not fit onto the detector, which causes certain problems during the reconstruction, but allows achieving of higher resolution in the always-visible region of the object (the region of interest). The research was focused on evaluation of ROI tomography approach on the TORATOM tomograph.
|
|
|
Tomography of a bronze axe of the Únětice culture, found in Kukleny, Hradec Králové
Kumpová, Ivana ; Vopálenský, Michal
It has been shown in the past that the computed X-ray tomography can bear significant new findings on the distribution of damaging and other structural details of the bronze findings. However, relatively high beam energies are necessary and it is not a priori ensured that the object under test would be penetrated with the radiation sufficiently. A big problem is also the photon scattering, which can make fine details indistinguishable. Therefore, a chosen Únětice culture axe has been submitted to a tomographical investigation in the laboratory of X-ray tomography of the Institute of Theoretical and Applied Mechanics of the Czech Academy of Sciences, v.v.i. The result should confirm the suitability of the method for investigations of other similar bronze findings.
|
|
|
Design of a suitable length standard for nanp-CT measuring device
Kožiol, Martin ; Jankových, Róbert (referee) ; Šrámek, Jan (advisor)
The diploma thesis deals with the design of three length standards, which will serve to ensure metrological traceability between Rigaku nano3DX, SIOS NMM-1, Zeiss UPMC Carat 850 and other devices located at ÚVSSR BUT and CEITEC Brno. The first part of the thesis focuses on the theoretical acquaintance with concepts closely related to the issue of ensuring metrological traceability. In addition, this section deals with computed tomography and the description of individual devices. The second part of the thesis is devoted to design, production process and testing of individual standards. The last part describes the ensuring the calibration of the smallest standard, the so-called Nano standard and the calculation of the uncertainty of measuring its calibrated length. At the end of the thesis, the outputs of these activities are evaluated.
|
|
|
Reduction Of Metal Artefacts In Ct Data With Submicron Resolution Using Dual-Target Ct
Víteček, Jakub ; Šalplachta, Jiří
The article deals with the possibility of the metal artefact reduction in computed tomography (CT) data with submicron resolution using dual-target CT. The sample is scanned twice at different acquisition parameters, at two different energy spectra. Dual-energy data are then used for easier localisation and segmentation of metal areas and the final combination of low and high-density materials. The final images are compared with the projection-based metal artefact reduction (MAR) algorithm and the commercial program VGStudio MAX 3.1. The results show good functionality of the proposed method and potential for further development.
|
guest ::
