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Minimization number of measured data for magnetostatic field mapping
Csonka, Gábor ; Bartušek, Karel (referee) ; Dědková, Jarmila (advisor)
This work deals with questions of mapping statical magnetical field and methods analyses plumbed dates. There is mentioned solving of problems and interpretation of results. Work is centered on evaluation map of magnetic field in workspace of MR tomography from data measured on surface shere. Imposition of submission is proposition acceptable mathematical method and trought program MATLAB compile algorithm for interpretation map magnetic field. In work is further included calculation resulting values of coefficients for induction of magnetic field for selected parts of sphere. By force of admeasurement were experimentally verifyded values wich from the work proceed. Designed method is possible to use for calculation of coefficeints for magnetic induction at any point on sphere from booked up dates.
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Impact of conductive material on RF magnetic field deformation
Vondra, Petr ; Steinbauer, Miloslav (referee) ; Dědková, Jarmila (advisor)
The work analyses formation of deformations of RF magnetic field within the environment of electrically and magnetically conductive materials. An analytic solution of the problem is created and the problems of numerical modeling are solved. In theoretical way, the work also familiarize with the use of magnetic resonance imaging method - the spin echo method (SE), with its features and possibilities of its use within the aim of the project. This method is used for experimental measurements of electrically conductive materials in the NMR laboratory in ISI AV Czech Republic. Results of the simulation are compared with results of the experimental measurement.
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Parameter optimization of MR sequences for magnetic susceptibility measurement
Pinkava, Jan ; Bartušek, Karel (referee) ; Steinbauer, Miloslav (advisor)
The Bachelor thesis deals with measuring magnetic susceptibility by means of nuclear magnetic resonance. Magnetic field is affected and deformed by various materials. The range and the shape of the deformation is caused by susceptibility. The thesis contains a 2D numerical model of a sample in a magnetic field 4.7 T. The results are compared with values obtained by a tomographic measurement. The second part of the thesis contains a 3D numerical model of diamagnetic and paramagnetic material. Moreover, a comparison with values measured in reality is drawn.
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The Study of Artifacts in MR Tomographic Images for Medical and Technical Applications
Al Khaddour, Mouin ; Frollo, Ivan (referee) ; Jiřík, Radovan (referee) ; Fiala, Pavel (advisor)
Tato disertační práce analyzuje artefakty v NMR obrazech. V lékařské praxi mohou artefakty zabránit diagnostice patologických tkání, a proto je třeba tyto nežádoucí jevy odstranit. Vzhledem k nutnosti vyloučit artefakty způsobené nehomogenitou statického magnetického pole jsou v dané souvislosti diskutovány také nové možnosti měření deformací. Práce popisuje metodu pro měření základního pole i RF pole a jejich nehomogenit na základě měření MR obrazů T2 a T2*. Metoda kombinuje akviziční postupy pro spinové a gradientní echo za účelem rozlišení relaxačních časů T2 a T2*. V této souvislosti také vyvstává potřeba provést exponenciální aproximaci relaxačního procesu. Experimentální výsledky pro plastové i měděné vzorky jsou prezentovány v příslušné části práce. Pokud jde o vlastní členení popisovaných jevů, je třeba uvést, že významný problém představují artefakty způsobené magnetickou susceptibilitou. Různé hodnoty magnetické vodivosti na rozhraní mezi dvěma materiály mohou způsobit deformaci magnetického pole, přičemž může dojít i k úplné ztrátě signálu.
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Parameter optimization of MR sequences for magnetic susceptibility measurement
Pinkava, Jan ; Bartušek, Karel (referee) ; Steinbauer, Miloslav (advisor)
The Bachelor thesis deals with measuring magnetic susceptibility by means of nuclear magnetic resonance. Magnetic field is affected and deformed by various materials. The range and the shape of the deformation is caused by susceptibility. The thesis contains a 2D numerical model of a sample in a magnetic field 4.7 T. The results are compared with values obtained by a tomographic measurement. The second part of the thesis contains a 3D numerical model of diamagnetic and paramagnetic material. Moreover, a comparison with values measured in reality is drawn.
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Minimization number of measured data for magnetostatic field mapping
Csonka, Gábor ; Bartušek, Karel (referee) ; Dědková, Jarmila (advisor)
This work deals with questions of mapping statical magnetical field and methods analyses plumbed dates. There is mentioned solving of problems and interpretation of results. Work is centered on evaluation map of magnetic field in workspace of MR tomography from data measured on surface shere. Imposition of submission is proposition acceptable mathematical method and trought program MATLAB compile algorithm for interpretation map magnetic field. In work is further included calculation resulting values of coefficients for induction of magnetic field for selected parts of sphere. By force of admeasurement were experimentally verifyded values wich from the work proceed. Designed method is possible to use for calculation of coefficeints for magnetic induction at any point on sphere from booked up dates.
|
|
|
Impact of conductive material on RF magnetic field deformation
Vondra, Petr ; Steinbauer, Miloslav (referee) ; Dědková, Jarmila (advisor)
The work analyses formation of deformations of RF magnetic field within the environment of electrically and magnetically conductive materials. An analytic solution of the problem is created and the problems of numerical modeling are solved. In theoretical way, the work also familiarize with the use of magnetic resonance imaging method - the spin echo method (SE), with its features and possibilities of its use within the aim of the project. This method is used for experimental measurements of electrically conductive materials in the NMR laboratory in ISI AV Czech Republic. Results of the simulation are compared with results of the experimental measurement.
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