Modeliranje MRI zavojnice pomoću programskog paketa COMSOL

undergraduate thesis

• Title (english): Modeling of MRI coil with COMSOL
• Author: Lucija Vrbanc
• Mentor: Bojan Trkulja (mentor)
• Committee member: Bojan Trkulja (predsjednik povjerenstva)
• Committee member: Sead Berberović (član povjerenstva)
• Committee member: Ana Drandić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; Zagreb
• Defense date and country: 2020-08-31, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering

Abstract

Oslikavanje dijelova tijela tehnikom magnetske rezonancije je vrijedna dijagnostička metoda temeljena na međudjelovanju jezgara vodika u ljudskom tijelu i magnetskog polja proizvedenog MRI uređajem. Zavojnice su jedne od najvažnijih dijelova MRI uređaja jer pravilnim korištenjem i dizajnom osiguravaju homogenu raspodjelu magnetskog polja u uređaju što vodi do kvalitetnih i detaljnih slika. Kavezne radiofrekventne zavojnice rade na principu rezonatore te su najčešće korištene u MRI uređajima jer na sebi imaju dodatne utore pomoću kojih se lako podešava kvadraturna pobuda i dodaje dodatni kapacitet u zavojnicu. Korištenjem oba navedena svojstva, kvadraturne pobude i namještanja optimalne vrijednosti kapaciteta zavojnice, dobiva se homogena raspodjela magnetskog polja. Pomoću COMSOL Multiphysics® softwarea modelira se radiofrekventna niskopropusna kavezna zavojnica te se podešavaju vrijednosti kapaciteta do postizanja optimalne vrijednosti koja je u primjeru ovog završnog rada 28 pF.

Abstract (english)

Magnetic resonance imaging is a valued diagnostic tool, based on the interaction of hydrogen nuclei found in a human body and the magnetic field which is generated by the MRI device. Magnetic coils are one of the most important parts od the MRI device because by implementing the right techniques and design they can generate homogeneous magnetic fields which are crucial for obtaining high resolution images. Birdcage radio frequency coils imitate a resonator and they are most commonly used in the MRI devices. Because of their lumped ports it is simple to acquire a quadrature excitation and an optimal value of capacitive elements in the coil. Both quadrature excitation and an optimal value of capacitance are important for generating a homogeneous magnetic field by the coil. Using the COMSOL Multiphysics® software a low pass radio frequency coil is designed and used for finding the optimal capacitance value which is calculated to 28 pF.

• Keywords: Tehnika oslikavanja magnetskom rezonancijom; jezgre vodika; precesija; longitudinalna i transverzalna magnetizacija; RF puls; Larmorova frekvencija; vrijeme relaksacije; RF zavojnice; kavezne zavojnice; homogeno magnetsko polje; kvadraturna pobuda; metoda koncentriranih parametara; metoda konačnih elemenata
• Keywords (english): Magnetic Resonance Imaging; hydrogen nuclei; precession; longitudinal and transversal magnetization; RF pulse; Larmor frequency; relaxation time; RF coils; birdcage coils; homogeneous magnetic field; quadrature excitation; Lumped Circuit Element Method; Finite Element Method
• Language: croatian
• URN:NBN: urn:nbn:hr:168:227163
• Study programme: Title: Electrical Engineering and Information Technology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka elektrotehnike i informacijske tehnologije (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka elektrotehnike i informacijske tehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2023-01-14 10:13:48