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Module for detection of ionizing radiation
Matějka, Tomáš ; Džbánek, Lukáš (referee) ; Kubíček, Michal (advisor)
This thesis deals with design of detector of ionizing X-ray radiation. Conventional PIN photodiodes are used for construction of the detector. The thesis describes issue of using PIN photodiodes for X-ray and gamma radiation detection. Transimpedance amplifier is designed with two diferent modes of detection. Both amplifier variants are compared and their suitability for specific applications is discussed. The thesis describes principle of converting analog signals to digital and describes concept of bus for multiple detectors connection to central unit. Options for paralel data processing are discused in last part of thesis. The detector is implemented and measured values are compared with simulations.
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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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Modern Imaging Techniques in Medicine
Pařízek, Aleš ; Neuwirthová, Ludmila (referee) ; Rujbrová, Šárka (advisor)
Cílem této práce je popsat základní principy a fyzikální veličiny spjaté s jednotlivými zobrazovacími metodami a poté jednotlivé metody porovnat. Práce popisuje vznik rentgenového záření, jeho interakci s různými materiály a metody snímaní pro vytvoření obrazů. Dále se práce zabývá základním principem vytvoření 3D obrazů pomocí počítačové tomografie a jednotlivými generacemi tomografických strojů. V poslední části se práce věnuje principu nukleární magnetické resonance a základním parametrům pro vytvoření obrazů pomocí MRI systémů.
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Construction of motorized filter changer for tomographic system Rigaku Nano3DX
Maleček, Lukáš ; Nožičková,, Dominika (referee) ; Zikmund, Tomáš (advisor)
X-ray computed tomography is a technique that finds widespread application nowadays. The initial use of this technique was mainly in medical diagnostics. The achievable accuracy of this technique has been progressively improved so much that today the computed tomography finds applications even in the field of industry. It is a non-destructive method of three-dimensional imaging of the internal structures of the examined objects. The quality of the resulting CT data is influenced by several factors. One of these factors is the property of X-rays, which we use for measurements. We are able to partially alter the properties of X-rays and thus obtain higher quality CT data, without the occurrence of some tomographic artifacts. The main way how we can change the properties of the generated X-rays is called additional filtration. This work deals with the study of X-ray spectra, based on which X-ray filters are optimized, to achieve the most efficient filtration. The main aim of this bachelor thesis is also the construction and production of a motorized changer of these filters, which should cause the speeding up the process of setting the whole CT measurement and allow the development of new computed tomography techniques.
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Application of non-destructive methods determining the quality of glued wood bondlines
Dvořáková, Martina ; Brožovský, Jiří (referee) ; Vaněrek, Jan (advisor)
The presented bachelor thesis is focused on the evaluation of timber elements by using non-destructive methods which are intended for the evaluation of glue lines. The main part of the work is focused on summarizing and the detailed description of selected non-destructive methods which can be used for glue line evaluation. There is also carried out the researche of selected scientific articles describing the application of non-destructive methods with regard to the evaluation of timber elements.
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Analysis of Defects on PCB Using X-RAY
Mlýnek, Martin ; Vala, Radek (referee) ; Řihák, Pavel (advisor)
This thesis is focused on BGA packages and fault detection after rework using X – Ray. There is a description of BGA packages by carrier substrate, techniques of connecting on chip, from mounting packages to repair printed circuit boards (hereafter PCB). Thesis summarizes description of defects, which are created after rework process. There is also description of X – Ray as method for analyzing defects. X – PLANE method used to detect internal structure of BGA packages and it was confirmed by microsection and by software for reconstruction. Description of automatic and manual measurement is follow.
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Laser-driven hard X-ray source for imaging applications
Lamač, Marcel ; Nejdl, Jaroslav (advisor)
With the advent of high-power lasers in recent decades, a unique source of hard X-ray radiation has become availible. This source of collimated, broadband, femtosecond, incoherent and hard X-ray radiation is produced when a focused laser with intensity above 10^18 W/cm^2 collides with a gas target. The strong electric field of the laser pulse ionizes the gas and interacts with the plasma generating a strong plasma wake wave. This space charge separation inside the target generates longitudal electric fields of the order of 100 GV/m. This resulting electrostatic wakefield accelerates the electrons to relativistic velocities and causes them to travel in oscillatory motion behind the laser pulse, producing hard and collimated X-ray radiation. This thesis is focused on a theoretical evaluation and an experimental design of this laser-plasma X-ray source. Furthermore, we consider the source's unique properties for novel imaging applications.
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Optimization of X-ray computed tomography method for imaging of low-density materials
Maleček, Lukáš ; Oberta, Peter (referee) ; Zikmund, Tomáš (advisor)
X-ray computed tomography is a technique enabling three-dimensional non-destructive imaging of the internal structure of measured objects. This imaging method has become a standard tool utilized in various fields, including medicine, industry, and science. Conventional X-ray computed tomography is based on the absorption of X-rays as it is passing through the measured object. However, this conventional imaging approach has its limitations, particularly when imaging objects with low density that causes only low X-ray attenuation. In such cases, sufficient contrast between the measured object and the background is not achieved. This thesis focuses on the optimization of phase contrast imaging, which utilizes phase changes of radiation as it is passing through the sample to overcome the limitations of absorption-based computed tomography. The detection of phase changes is achieved in the thesis using the propagation-based method. The main goal is to develop a methodology for finding the optimal parameters for the acquisition of tomographic data and also for the following processing of obtained X-ray projections. The results are qualitatively and quantitatively evaluated to assess the benefits of the developed methodology.
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Noise reduction in high resolution computed tomography data
Tkadlecová, Markéta ; Chmelík,, Jiří (referee) ; Zikmund, Tomáš (advisor)
Vzhledem ke komplexnosti procesu akvizice dat výpočetní tomografie (CT) je šum v rentgenových snímcích nevyhnutelný a může vést ke zkreslení získané informace. Proto by měl být co nejvíce potlačen. Dosud se výzkum zaměřoval především na redukci šumu v CT datech u lékařských CT s nízkými dávkami, zatímco o šumu a jeho potlačení v CT datech s vysokým rozlišením je známo jen málo. Tato redukce může probíhat v oblasti rentgenových snímků, v průběhu tomografické rekonstrukce nebo v oblasti tomografických řezů. Tato práce se zabývá především redukcí šumu v rentgenových snímcích a tomografických řezech. Prvním krokem k nalezení komplexní metodiky je určení rozdělení a matematického modelu šumu přítomného v rentgenových snímcích. Tento model byl určen pomocí snímků bez přítomného vzorku, které byly pořízeny s různými expozičními časy. Pomocí stanoveného modelu byl simulován šum ve fantomovém datasetu. Vybrané algoritmy byly testovány na projekčních snímcích a tomografických řezech fantomu a porovnávány jak subjektivně, tak objektivně pomocí metrik kvality obrazu. Strategie s nejlepšími výsledky byly dále testovány na naměřených CT datech z CT systému Rigaku nano3DX s vysokým rozlišením a byly popsány jejich výhody, omezení a možnosti využití.
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Optimization of the Radiological Protection in Diagnostic X-ray Examinations
GREGOROVÁ, Tereza
This thesis deals with the topic of optimization of radiation protection of patients at a radiodiagnostic workplace. It discusses the possibilities of protecting patients from X-ray radiation in radiodiagnostics, both by technical parameters that can influence the dose and by the use of protective shielding, both in the primary radiation beam and outside it. In the practical part I focused on the calculation of diagnostic reference levels for selected examinations. Examination data was obtained from the DICOM header from the Dicompass viewer. For the calculation, I chose the chest examination in PA projection and the skull examination in AP projection lying on the examination table. Exposure parameters from three stationary scanners on which both selected examinations are currently routinely performed were analyzed. The observed values of input surface kerma and surface kerma for each scans were compared with the values of local diagnostic reference levels and with the values of national diagnostic reference levels. There are no national diagnostic reference levels for pediatric examinations, so I used the 2015 European Guidelines on DRLs for Pediatric Imaging document, which contains diagnostic reference levels for pediatric patients, to compare the values. The content of this paper can serve as a basic overview of optimizing radiation protection and calculating diagnostic reference levels for healthcare professionals and the general public.
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