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Measuring Card For Electrical Impedance Tomography V20
Balajka, Martin
This project aims to improve the first version of an electrical impedance tomography card. The main enhancement of this version is the replacement of Raspberry Pi with a better platform - STM32, implementation of voltage and phase shift measurements, and error correction in the first version. The main reason for moving from Raspberry Pi to STM32 is speed, power consumption and ease of use for the end user.
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Pulmonary pathophysiology during circulatory support.
Popková, Michaela ; Mlček, Mikuláš (advisor) ; Rohn, Vilém (referee) ; Otáhal, Michal (referee)
Introduction: Left-ventricular (LV) distension and consequent pulmonary congestion are complications frequently discussed in patients with severe LV dysfunction treated with veno- arterial extracorporeal membrane oxygenation (VA ECMO). The goal of this study was to describe the influence of high VA ECMO flows to LV distension, lung hemodynamics, and lung fluid accumulation. Methods of LV decompression were studied to prevent lung edema. Methods: In all experiments porcine models under general anesthesia were used. The effects of high extracorporeal blood flow (EBF) on LV heart work were assessed in a chronic heart failure model. The effects of LV afterload on lung fluid accumulation were evaluated by electrical impedance tomography (EIT) on acute heart failure models. Phase and frequency filtration and mathematical analysis were applied to the raw EIT data. Subsequently, mini- invasive techniques of LV decompression were evaluated for LV work. Results: The stepwise increases of VA ECMO flow improved both hemodynamic and oxygenation parameters. Nevertheless, it also caused distension and increased work of LV. The rise in EBF led to increased pulmonary capillary wedge pressure and lung fluid accumulation assessed by EIT in heart failure. The methods for LV decompression (Impella pump, atrial...
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Measuring Card For Electrical Impedance Tomography
Balajka, Martin
This project aims to design and to implement measuring card for electrical impedance tomography (EIT). The main function of the card is to switch the voltage measuring electrodes and to select the feeding current polarity on any tomography electrode. The commonly used commercial cards utilize the relays. The main problems of this approach are speed of the switching, selfconsumption, size and signal noise. Our solution consists in utilizing the MOSFET technology with optocoupler to isolate the feeding and measuring electrodes galvanically. The MOSFET optocouplers are driven by the shift registers controlled by the Raspberry Pi Zero embedded system.
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Portable digitally controlled stabilized source of symmetrical voltage
Hynek, David ; Drexler, Petr (referee) ; Mikulka, Jan (advisor)
This thesis deals with a design of a power supply for a measuring equipment for a geophysical mapping intended to do a reconstruction of an electrical impedance of a ground environment of water reservoirs. The power source is going to be used for laboratory measurements and for outdoor experiments. The thesis describes the selection of suitable components, equipment design and testing. The theoretical part explains the functions of used components and the principle of an electrical impedance tomography. The conclusion summarizes the properties of the proposed solution and evaluates the final product.
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Acceleration Of Electrical Impedance Tomography
Algorithm With Open And Closed Domain
Model Evaluation
Dušek, Jan
The presented paper discusses the possibilities of parallelizing algorithms for the image reconstruction in the Electrical Impedance Tomography (EIT). The parallelization process was performed and tested with combination of Matlab and CUDA environment. A twenty-fold acceleration of the Jacobian calculation was achieved. Besides of the parallelization process, the important part of the EIT experiments was the selection of the computational mesh. These mesh elements are used for fast execution of the partial differential equation EIT model. Forward and inverse problems of the image reconstruction were simulated on the novel open domain. The optimized domain reduced error in the reconstructed image.
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Electrical impedance tomography of soft tissue
Pšenka, Marek ; Průša, Vít (advisor) ; Velímský, Jakub (referee)
Electrical impedance tomography of soft tissue This bachelor thesis presents an overview of electrical impedance tomography (EIT) as a proposed imaging technique with special focus on its applications in medicine. Amongst all of the areas being considered, the possibility of performing breast cancer examinations is given special focus. The author dicusses the motivation and rationale behind using EIT for this particular purpose and has gathered information about EIT systems which have been constructed to date. The reconstruction of a conductivity distribution within a physical body is a complex problem which necessitates the solution of a number of subproblems - starting with the calculation of these potential distribution within the body ending with the solution of an inverse boundary value problem. The thesis describes some aspects of these subproblems and presents their mathematical treatment. It concludes by testing the EIDORS software package which represents a reference implementation of algorithms for the EIT problem. 1
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Improvement of the Biomedical Image Reconstruction Methodology Based on Impedance Tomography
Kořínková, Ksenia ; Bartušek, Karel (referee) ; Bachorec, Tibor (referee) ; Dědková, Jarmila (advisor)
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.
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New Optimization Algorithms for a Digital Image Reconstruction in EIT
Kříž, Tomáš ; Koňas, Petr (referee) ; Král, Bohumil (referee) ; Dědková, Jarmila (advisor)
This doctoral thesis proposes a new algorithm for the reconstruction of impedance images in monitored objects. The algorithm eliminates the spatial resolution problems present in existing reconstruction methods, and, with respect to the monitored objects, it exploits both the partial knowledge of configuration and the material composition. The discussed novel method is designed to recognize certain significant fields of interest, such as material defects or blood clots and tumors in biological images. The actual reconstruction process comprises two phases; while the former stage is focused on industry-related images, with the aim to detect defects in conductive materials, the latter one concentrates on biomedical applications. The thesis also presents a description of the numerical model used to test the algorithm. The testing procedure was centred on the resulting impedivity value, influence of the regularization parameter, initial value of the numerical model impedivity, and effect exerted by noise on the voltage electrodes upon the overall reconstruction results. Another issue analyzed herein is the possibility of reconstructing impedance images from components of the magnetic flux density measured outside the investigated object. The given magnetic field is generated by a current passing through the object. The created algorithm for the reconstruction of impedance images is modeled on the proposed algorithm for EIT-based reconstruction of impedance images from voltage. The algoritm was tested for stability, influence of the regularization parameter, and initial conductivity. From the general perspective, the thesis describes the methodology for both magnetic field measurement via NMR and processing of the obtained data.
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