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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Analýza vrstvy nervových vláken pro účely diagnostiky glaukomu / Analysis of retinal nerve fiber layer for diagnosis of glaucoma

Vodáková, Martina January 2013 (has links)
The master thesis is focused on creating a methodology for quantification of the nerve fiber layer on photographs of the retina. The introductory part of the text presents a medical motivation of the thesis and mentions several studies dealing with this issue. Furthermore, the work describes available textural features and compares their ability to quantify the thickness of the nerve fiber layer. Based on the described knowledge, the methodology to make different regression models enabling prediction of the retinal nerve fiber layer thickness was developed. Then, the methodology was tested on the available image dataset. The results showed, that the outputs of regression models achieve a high correlation between the predicted output and the retinal nerve fiber layer thickness measured by optical coherence tomography. The conclusion discusses an usability of the applied solution.
102

Automatické generování okrajové plochy kraniálního implantátu / Automatic Producing of Cranial Implant Edge Surface

Hrdý, Libor January 2010 (has links)
This thesis is focused to problems of automatic generation of border surface for cranial implant. This document includes description of 3D modeling human tissue, followed with issue of cranial implant. Next it includes possible perspectives of solving automatic generation problems for implant border. Second half of this document is focused to implementation of tool for automatic generation of border surface. Final part deals with results of work with this tool.
103

Vylepšení metodiky rekonstrukce biomedicínských obrazů založené na impedanční tomografii / Improvement of the Biomedical Image Reconstruction Methodology Based on Impedance Tomography

Kořínková, Ksenia January 2016 (has links)
Disertační práce, jež má teoretický charakter, je zaměřena na vylepšení a výzkum algoritmů pro zobrazování vnitřní struktury vodivých objektů, hlavně biologických tkání a orgánů pomocí elektrické impedanční tomografie (EIT). V práci je formulován teoretický rámec EIT. Dále jsou prezentovány a porovnány algoritmy pro řešení inverzní úlohy, které zajišťují efektivní rekonstrukci prostorového rozložení elektrických vlastností ve zkoumaném objektu a jejích zobrazení. Hlavní myšlenka vylepšeného algoritmu, který je založen na deterministickém přístupu, spočívá v zavedení dodatečných technik: level set a nebo fuzzy filtru. Kromě toho, je ukázána metoda 2-D rekonstrukce rozložení konduktivity z jediného komponentu magnetického pole a to konkrétně z-tové složky magnetického toku. Byly vytvořeny numerické modely biologické tkáně s určitým rozložení admitivity (nebo konduktivity) pro otestování těchto algoritmů. Výsledky získané z rekonstrukcí pomocí vylepšených algoritmů jsou ukázány a porovnány.
104

Analýza 3D CT obrazových dat se zaměřením na stanovení hustoty kostních elementů / Analysis of 3D CT image data aimed at segmentation of bone elements and other specific tissue types

Kodym, Oldřich January 2017 (has links)
The goal of this thesis is to get acquainted with methods of determining bone mineral density from appropriate tissue types in diagnostic CT data and possibly modifying or extending them in order to make the bone quality diagnosis more reliable. The thesis begins by introducing the issue of determining bone quality. Next, a method that takes cortical bone deformations into account as well as bone mineral density is introduced. Accuracy assessment based on opinion of a medical expert suggests positive outcome of future objective accuracy assessment utilizing so far unavailable base of calibrated CT data, that is needed before deployment into clinical practice. If the accuracy of the suggested method is confirmed this way, this work provides a so far absent tool for fully automatic preventive diagnostics of osteoporosis.
105

Detekce a identifikace typu obratle v CT datech onkologických pacientů / Vertebra detection and identification in CT oncological data

Věžníková, Romana January 2017 (has links)
Automated spine or vertebra detection and segmentation from CT images is a difficult task for several reasons. One of the reasons is unclear vertebra boundaries and indistinct boundaries between vertebra. Next reason is artifacts in images and high degree of anatomical complexity. This paper describes the design and implementation of vertebra detection and classification in CT images of cancer patients, which adds to the complexity because some of vertebrae are deformed. For the vertebra segmentation, the Otsu’s method is used. Vertebra detection is based on search of borders between individual vertebra in sagittal planes. Decision trees or the generalized Hough transform is applied for the identification whereas the vertebra searching is based on similarity between each vertebra model shape and planes of CT scans.
106

Možnosti ERT a GPR pro analýzu polygonálních kryogenních struktur / Using ERT and GPR in polygonal patterned ground analysis

Široký, Jakub January 2014 (has links)
Polygonal cryogenic structures cannot be investigated with conventional methods as they could be harmed during measurement. A real3D GPR and ERT non-destructive surveys were used to examine and prove applicability for topsoil covered ice-wedge pseudomorphs and coarse-grained sorted polygons (patterned ground). A list of processing tools and algorithm suitable for such environments was created and tested. The benefits of 3D measurements are illustrated on horizontal slices and pseudo3D visualisation of 3D Cube. Basic morphometry characteristics of both forms were collected. Abilities of geophysical imaging for advanced shape characterisations are discussed, too. The low-frequency measurements gave better results at both sites. Pseudomorphs, 2 wide and up to 6,5 long, were found penetrating depth bigger than 3,5 . Sorted polygons, 2,5 wide in diameter, were depicted locked by stony ring of width around 1 . Sorting depth extends up to 0,54 depth for sure, perhaps more.
107

Výzkum sklivce a vitreoretinálního rozhraní u mikrovaskulárních chorob sítnice se zaměřením na oční komplikace diabetes mellitus. / Research of vitreous and vitreoretinal interface in microvascular retinal disorders focussed on eye complications of diabetes mellitus

Křížová, Libuše January 2016 (has links)
In this work I present conclusions of clinical-laboratory research focused on the patients with diabetic macular edema (DME). We performed biochemical and immunochemical analyses of vitreous samples that were collected during the pars plana vitrectomy. Moreover, at patients with non-proliferative diabetic retinopathy (NPDR) we assessed morphological characteristics of DME using optical coherence tomography (OCT). According to our findings, the vitreous and serum concentrations of uric acid and glucose were significantly higher in patients with diabetic retinopathy and DME compared to controls. Also total ratio (serum/ vitreous concentration) of uric acid and glucose was in diabetics significantly higher than in controls. The most important determinant of increasing concentration of both uric acid and glucose in the vitreous was the grade of diabetic retinopathy. Moreover, we demonstrated significant correlation between vitreous concentration of uric acid and concentration of the vascular endothelial growth factor (VEGF) in patients with DME and NPDR. We found further, that the volume of the macula (cube volume - CV) computed with the software of Cirrus HD-OCT correlates in diabetics significantly with the vitreous VEGF concentration, but not with uric acid. This OCT parameter could be used to...
108

Strukturní analýza vybraných silicidů přechodných kovů pomocí rentgenové difrakce a dynamického upřesňování dat z elektronové difrakce / Structure analysis of some transition metal silicides using X-ray diffraction and dynamical refinement against electron diffraction data

Antunes Corrêa, Cinthia January 2017 (has links)
Title: Structure analysis of some transition metal silicides using X-ray diffraction and dynamical refinement against electron diffraction data Author: Cinthia Antunes Corrˆea Department: Physics of Materials Supervisor: prof. RNDr. Miloš Janeček, CSc., Department of Physics of Materials Abstract: This thesis presents the crystal structure analysis of several transition metal silicides. The crystal structures were studied primarily by precession electron diffraction tomography (PEDT) employing the dynamical refinement, a method recently developed for accurate crystal structure refinement of electron diffraction data. The optimal values of the parameters of the method were proposed based on the comparison between the dynamical refinement of PEDT data and a high- quality reference structure. We present the results of the comparison using a Ni2Si nanowire with the diameter of 15 nm. The average atomic distance between the model obtained by the dynamical refinement on PEDT data and the one by single crystal X-ray diffraction was 0.006 ˚A. Knowing the accuracy and limitations of the method, the crystal structure of Ni3Si2 was redetermined on a nanowire with 35 nm of diameter. The model obtained had an average error in the atomic posi- tions of 0.006 ˚A. These results show that the accuracy achieved by the dynamical...
109

Anizotropní tomografie svrchního pláště pod Evropou / Anisotropic tomography of the European upper mantle

Žlebčíková, Helena January 2019 (has links)
Title: Anisotropic tomography of the European upper mantle Author: Helena Žlebčíková Department: Department of Geophysics, Faculty of Mathematics and Physics, Charles University Training institution: Institute of Geophysics of the Czech Academy of Sciences (IG CAS) Supervisor: RNDr. Jaroslava Plomerová, DrSc., IG CAS Consultants: RNDr. Vladislav Babuška, DrSc., IG CAS RNDr. Luděk Vecsey, Ph.D., IG CAS Abstract: Large-scale seismic anisotropy of the continental mantle lithosphere derived from joint inversion/interpretation of directional variations of P-wave travel-time residuals and SKS-wave splitting calls for orientation of the symmetry axes to be treated generally in 3D. Nevertheless, most of the tomography studies neglect the anisotropy of the body waves completely or they are limited to either azimuthal or radial anisotropy. Therefore, we have developed a code called AniTomo for coupled anisotropic-isotropic travel-time tomography of the upper mantle. The novel code allows inversion of relative travel-time residuals of teleseismic P waves simultaneously for 3D distribution of P-wave isotropic- velocity perturbations and anisotropy of the upper mantle. We assume weak anisotropy of hexagonal symmetry with either the 'high-velocity' a axis or the 'low-velocity' b axis. The symmetry axis is allowed to be...
110

Výzkum sklivce a vitreoretinálního rozhraní u mikrovaskulárních chorob sítnice se zaměřením na oční komplikace diabetes mellitus. / Research of vitreous and vitreoretinal interface in microvascular retinal disorders focussed on eye complications of diabetes mellitus

Křížová, Libuše January 2016 (has links)
In this work I present conclusions of clinical-laboratory research focused on the patients with diabetic macular edema (DME). We performed biochemical and immunochemical analyses of vitreous samples that were collected during the pars plana vitrectomy. Moreover, at patients with non-proliferative diabetic retinopathy (NPDR) we assessed morphological characteristics of DME using optical coherence tomography (OCT). According to our findings, the vitreous and serum concentrations of uric acid and glucose were significantly higher in patients with diabetic retinopathy and DME compared to controls. Also total ratio (serum/ vitreous concentration) of uric acid and glucose was in diabetics significantly higher than in controls. The most important determinant of increasing concentration of both uric acid and glucose in the vitreous was the grade of diabetic retinopathy. Moreover, we demonstrated significant correlation between vitreous concentration of uric acid and concentration of the vascular endothelial growth factor (VEGF) in patients with DME and NPDR. We found further, that the volume of the macula (cube volume - CV) computed with the software of Cirrus HD-OCT correlates in diabetics significantly with the vitreous VEGF concentration, but not with uric acid. This OCT parameter could be used to...

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