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Impact of Inaccuracy in fMRI Experimental Stimulation
Mikl, Michal ; Kremláček,, Jan (referee) ; Michálek, Jiří (referee) ; Drastich, Aleš (advisor)
Aim of this work is to study the impact of inaccuracy in execution of required task (inaccuracy in subject’s behavioral response to experimental stimulation) by person who undergoes fMRI examination. The work is solved in several stages. First, theoretical analysis of inaccuracy in fMRI experiment was performed, and simulations with synthetic data were created. Several variables in general linear model and t-statistics were followed. We found that estimated effect size depends linearly on covariance between the corresponding columns of X and D matrices or their linear combination. The component of residual variance caused by inaccuracy is negligible at real-life noise levels. In such case, moreover, the dependence of t-statistics on inaccuracy becomes linear. Next, our theoretical results (dependencies/characteristics of variables) were verified using real data. All results were confirmed. Last, I focused on possible practical use of the uncovered characteristics and dependencies. Optimization of experimental design with respect to inaccuracy, correction of inaccurate results and reliability of inaccurate results are introduced and discussed. Especially, the calculation of maps of maximal tolerable inaccuracy can be useful to find robust or weak (tending to be not detected or to be significantly different from accurate value) activation in real fMRI experiments.
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Analysis of infrared acquisition parameters
Zembol, Filip ; Drastich, Aleš (referee) ; Čech, Petr (advisor)
The topic of my thesis is the analysis of parameters of the infrared imaging and the usage of these parameters for the design of a thermographic equation and a programme in the MATLAB environment in which the termography formula and the influence of the particular quantities, which take part in it, will be graphically depicted. In the thesis we will first of all introduce the infrared radiation, its types and features. With the help of the particular radiation laws and distracting elements of the infrared radiaton a formula trimming the distracting elements of the thermal relief will be designed. This formula will enable us to count the emission surface temperature of the scanned scene (grey body) and thus eliminate the elements influencing the resulting temperatures of the scanned scene. Furthermore, a programme which will image the IR acquisition model (thermogram) on the basis of the thermography equation will be designed. The thermogram will change in dependence on the changes of the thermography equation quantities. The change will be expressed by the shift of the color spectrum (thermographic scale). This programme graphically presents the changes of the quantities influencing the resulting scene and provides a better grasp of the influence and the function of particular quantities in the thermographic equation.
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Image flow time sampling
Němec, Miroslav ; Kolář, Radim (referee) ; Drastich, Aleš (advisor)
The aim of this Master’s thesis is to develop a theoretical introduction to the issue of the image flow time sampling, taking into account the various factors that affect sampling. Furthermore, there is proposed idea diagram of the model, which will simulate the events described, and created the model in the programming environment Matlab. Finally, there are defined the labs that will support teaching dealing with the imaging systems.
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Simulation of the CT X-ray Detectors
Koutek, Petr ; Walek, Petr (referee) ; Drastich, Aleš (advisor)
The bachelor thesis deals with the basic properties of the detectors used in X-ray CT, and their influence on the choice of acquisition parameters. The theoretical part summarizes the general issues of projection reconstruction view and basic characteristics of the detectors. In the practical part is created simulator which simulate the effect of deacy time, afterglow and the light output.
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X-ray beam hardening effect simulation
Šlof, Michael ; Balogh, Jaroslav (referee) ; Drastich, Aleš (advisor)
This bachelor thesis concerns itself with X-ray beam hardening effect simulation by filtering. The initial part introduces a theoretical background to the given topic. It is crucial to understand the underlying physical principles and laws prior to analysis so the X-ray radiation theory is introduced first. Units, quantities and an X-ray tube are also outlined as part of the X-ray theory. The practical part focuses on X-ray beam hardening effect simulation in programming language MATLAB. A strong emphasis is placed on parameter input, ease of operation and outcome analysis of the desired process as related to the X-ray beam hardening effect.
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X-ray computed tomography fluoroscopy simulation
Bainar, Petr ; Kolář, Radim (referee) ; Drastich, Aleš (advisor)
The aim of the thesis is to design and implement a simulator of image reconstruction during x-ray computed tomography fluoroscopy. Apart from quantitative evaluation of particular imaging process parameters influence, the intended program application will lie in optimization of these parameter values. Introductory part is focused on brief theoretical description of x-ray computed tomography imaging process. Emphasis is placed on fluoroscopy-specific approaches, particularly the division of scanned projections into chosen amount of sectors as well as fluoroscopic imaging process evaluation methods. The subsequent part deals with program implementation and its limitations and sketches the possible working framework. Moreover, one of the chapters is devoted to optimization of imaging process parameters measurement. The final part aims at impact analysis of particular process parameters as well as fluoroscopic imaging process optimization approaches. The thesis consists also of a didactic simulator enabling real-time intervention simulation with manual instrument manipulation. Since both simulators are intended for teaching purposes, the thesis is supplemented with a laboratory exercise draft.
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Analysis of infrared acquisition parameters
Zembol, Filip ; Drastich, Aleš (referee) ; Čech, Petr (advisor)
The topic of my thesis is the analysis of parameters of the infrared imaging and the use of radiation laws for the formation of a thermographic equation, which will include the impact of surrounding factors on the resulting temperature relief of the scanned object. These factors include the temperature of the surrounding atmosphere, temperature of the surrounding radiation sources, emissivity coefficients, reflection and transmission. On the basis of this equation a programme will be created in the MATLAB environment where the resulting temperature relief of the simulated object and the impact of the particular parameters from the equation will be graphically depicted. In the thesis we will first of all introduce the infrared radiation, its types and features. With the help of the particular radiation laws and distracting elements of the infrared radiation a formula including the distracting elements appearing during scanning of the thermal surface relief will be formed. This formula will enable us to count the surface temperature of the scanned scene and to determine the final temperature without the impact of the unwanted parameters. Furthermore, a programme which will image thermograms on the basis of the thermography equation will be designed. The thermogram will change in dependance on the changes of the parameters in the thermography equation. The change will be expressed by the change of temperatures in the scanned scene and by the shift in the colour spectrum (thermographic scale). This programme will graphically present the changes of the quantities influencing the resulting temperature division in the scene and will provide a better grasp of the influence and the function of particular quantities in the thermographic equation.
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Pseudo-colour imaging of the monochromatic pictures
Boleček, Libor ; Drastich, Aleš (referee) ; Říčný, Václav (advisor)
Diploma thesis displaying black and white image in false color includes a study of methods and creation of computer software. The main function of the program is to convert the monochrome image into the pseudo colors. This procedure is achieved increasing the diagnostic yield of image. The program may find application in medical field. The pseudocoloring is used several different methods for obtaining the best results, combined with modifications increasing brightness scale image contrast images. The program is created in the programming environment of Visual Studio 2008 and written in C # programming language. Entry program is monochrome images in various formats (JPEG, BMP). The output of the program can be printed in a false-color image or stored image again in several different formats.
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X-ray beam hardening effect simulation
Milek, Jakub ; Kolář, Radim (referee) ; Drastich, Aleš (advisor)
At the beginning of this work the physics related background and it’s interaction with matter is described, followed by explanation of filters influence on X-ray spectrum. Linear attenuation coefficient is described and so are other related physical quantities. In the end the description of a simulator is presented.
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Acquisition contrast of X-ray projection and projection-reconstruction imaging
Zubal, Lukáš ; Jiřík, Radovan (referee) ; Drastich, Aleš (advisor)
The work resulted in computer application which simulates X-ray projection and projection-reconstruction imaging in voxel space. Application user becomes acquainted with terms of acquisition contrast of X-ray projection and projection-reconstruction imaging. The thesis takes detailed look at algorithms of computing ray integrals and X-ray projection and projection-reconstruction imaging. The potential of modern computer graphics is also discussed.
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