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Determination of measurement uncertainties of holes in steel components by X-ray computed tomography
Blažek, Pavel ; Šperka,, Jiří (referee) ; Kalasová, Dominika (advisor)
This thesis deals with determination of uncertainties of dimensional measurements in X-ray computed tomography. CT measurement process involves a lot of steps and is affected by a lot of factors, which depend not only on the CT system parameters but also on the measured sample and the operator. All of this influences the resulting uncertainty. Experimental method involving calibrated workpieces allows to determine the uncertainty without perfect knowledge of the influence factors. This method is described in standards ISO 15530-3 and VDI/VDE 2630 2.1. The aim of this work is to experimentally determine the uncertainty of tomographic measurement of dimensions of holes of selected workpiece on a CT device GE phoenix v|tome|x L240. Hence, a demonstration workpiece has been designed and manufactured. The dimensional CT measurements of inner and outer diameters have been performed on this sample. The reference measurement has been performed using a length measuring machine SIP 1002. The uncertainty of measurement depending on penetration thickness of the material has been determined.
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Analysis of Baroque sculpture based on X-ray fluorescence imaging and X-ray\ncomputed tomography data fusion
Vavřík, Daniel ; Kumpová, Ivana ; Vopálenský, Michal ; Lauterkranc, J.
It is advantageous to combine information about geometry and the inner structure of historical artifacts with information about the elemental composition of decorative layers, typically covering historical wooden sculptures. X-ray computed tomography describing artifact structure is quite common and easy. Standard X-ray fluorescence (XRF) analysis of decorative layers is typically done for several selected spots of the artifact’s surface utilizing single pad detector. XRF imaging fully describing the surface’s elemental composition is commonly done for flat objects, while time consuming XRF tomography is applied to relatively small objects. It will be shown in this work that an effective fusion combination of XRF imaging and X-ray tomography describing the whole object can be realized even when using a limited number of XRF images.
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Optimization of acquisition parameters in radiography and tomography
Vopálenský, Michal ; Vavřík, Daniel ; Kumpová, Ivana
Contrast in radiographic images is one of the most important parameters both in radiography and tomography. This paper investigates the possibility of adjusting the radiographic parameters, in particular the accelerating voltage of the X-ray tube, in order to maximize the difference in the detected intensity in response to the change in the thickness of the investigated object. Simplified model is used that allows finding the optimal operating point for the given material and thickness without an apriory knowledge about the X-ray spectra, detector response and the material composition. It is shown that in case of small changes of thickness, the optimum is met when the detected intensity behind the object of certain thickness is at approx. 37 % of the full range (i.e., of the value that would be measured under the same conditions in the absence of the object). In spite of simplifications made, the theoretical model shows a very good correspondence with the experimental data. A brief consideration is made on the case of a general difference in thicknesses.
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Noise reduction for low dose CT data
Holub, Zbyněk ; Odstrčilík, Jan (referee) ; Chmelík, Jiří (advisor)
The aim of this work is comparing of methods which are used for filtration of low dose CT images. This filtration is realized due to suppress of noise in final image and better visble of details. This work contains design and realization of selected filtration methods. Wiener´s correction coefficient and filtration with usage of WAVELET TRANSFORM are introduced in detail view. These methods are created in Matlab®; with the option to set para-meters of filteres. The filters are tested on 3D CT lungs image data. In the end of this work is a ranking of filter‘s quality and choosen of the most optimal approach.
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Data processing for tomographic reconstruction
Dospiva, Jindřich ; Žídek, Jan (referee) ; Zikmund, Tomáš (advisor)
This thesis deal with data processing from x-ray tomographic system. The primary focus is put on the description of projection refining taking place before tomographic reconstruction. The particular method for data processing from system Nano3DX is also suggested. It uses open software ASTRA tomography toolbox, which enable executing of tomographic reconstruction on the graphics card in MATLAB environment. There is also used correction for sample movement, denoising algorithm in projections and calculation the centre of rotation. Results of proposed procedure are demonstrated on tomographic data from measured samples and compared with processing software from the manufacturer.
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X-ray computed tomography of cartilage tissue of embryos
Tesařová, Markéta ; Křivánek,, Jan (referee) ; Zikmund, Tomáš (advisor)
Research of the cartilage is standardly realized by optical microscopy on histological slices. However, for better understanding of shape-organizing processes, imaging in 3D is required. This thesis deals with X-ray computed tomography of mouse embryos. Specifically, it focuses on visualization of craniofacial cartilage. The thesis summarizes the basic principles of X-ray computed tomography. Short research study dealing with staining of soft tissues for X-ray is also provided. The procedure of implementation of the tomographic measurement of mouse embryos stained by PTA is described. This procedure includes the staining protocol, fixing the sample and setting of the CT machine. Subsequent segmentation and creating of a 3D model of cartilage is also desribed. Results for every step of this procedure are demonstrated at the mouse embryos of developmental stage from 12.5 to 17.5 days. In order to improve data quality and standardization of the whole process, parameters of X-ray tube and temperature conditions during the tomographic measurement are explored. Finally, resulting models of craniofacial cartilage are shown with the possibility of subsequent analysis.
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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.
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Optimization of tomographic station GE phoenix adjustment for plastic components including metal parts
Starý, Přemysl ; Petrilak, Michal (referee) ; Zikmund, Tomáš (advisor)
X-ray computed tomography is a tool mostly used in a medical diagnosis. A development of the technique and an improvement an in accuracy of tomographic systems enabled an utilization of the tomography in industrial applications. The tomography allows non-destructive analysis of inner structure. There is a negative influence of a reconstructed area if a low-absorption and high-absorption materials are scanned together. This influence makes analysis of the inner structure impossible. There are two options to eliminate these artifacts. We can use algorithms to reduce metal artifacts, or we can try to avoid them when performing the scan. This bachelor thesis focuses on an optimization of tomographic station adjustment for the plastic components including metal parts. The effect of an usage of X-ray filter or collimator and effect of a sample orientation on data quality will be observed. We use tools like contrast, noise and edge sharpness to evaluate data quality.
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The X-ray CT lab and the research at the Institute of Geonics AS CR
Souček, Kamil ; Staš, Lubomír
In recent decades, non-destructive methods of materials analysis (Desrues 2006) have been used increasingly for the study of different kinds of materials. Especially, it concerns the method of the X-ray computed tomography (CT). This technique was invented in 1970's (Hounsfield 1972) and it quickly became an indispensable part of medicine. In the 1980's, this success in medicine encouraged the research and development of the X-ray CT applications in the field of materials engineering and consequently also in the field of geomaterials (Otani, Obara 2004). Nowadays, many applications are possible due to high resolution of individual building units in the tomographic cross-sections (so called voxels) with dimensions of units or tens of micrometres. To get this resolution, the use of the 2D and the 3D high-resolution X-ray CT, or the micro-CT with micro-focal sources of X-rays, and suitable linear or flat (2D) X-Ray detectors are preferred.
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