3d simulation of magneto-mechanical coupling in mri scanners using high order fem and pod

• Autores: Marcos Seoane Chouciño
• Directores de la Tesis: P.D. Ledger (dir. tes.), Antonio Javier Gil Ruiz (codir. tes.), Sergio Zlotnik (codir. tes.)
• Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2020
• Idioma: español
• Materias:
  • Matemáticas
    • Ciencia de los ordenadores
      • Simulación
    • Análisis numérico
      • Ecuaciones diferenciales en derivadas parciales
  • Física
    • Electromagnetismo
      • Interacción de ondas electromagnéticas con la materia
    • Mecánica
      • Mecánica de medios continuos
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• Resumen

  • Magnetic Resonance Imaging (MRI) scanners have become an essential tool in the medical industry due to their ability to produce high resolution images of the human body. To generate an image of the body, MRI scanners combine strong static magnetic fields with transient gradient magnetic fields. The transient magnetic fields give rise to the appearance of eddy currents in conducting components. These eddy currents, in turn, result in electromagnetic stresses, which cause the conducting components to deform and vibrate. The vibrations are undesirable as they lead to a deterioration in image quality and to the generation of noise. The eddy currents, in addition, lead to heat being dissipated and deposited into the cryostat, which is filled with helium in order to maintain the coils in a superconducting state. This deposition of heat can cause helium boil off and potentially result in a costly magnet quench. Understanding the mechanisms involved in the generation of these vibrations and the heat being deposited into the cryostat are, therefore, key for a successful MRI scanner design. This involves the solution of a coupled magneto-mechanical problem, which is the focus of this work. In this thesis, a new high order finite element methodology for the solution of three-dimensional magneto-mechanical problems with application to MRI scanner design is presented.

    This finite element methodology results in the accurate and efficient solution of the magneto-mechanical problem of interest.

    However, in the design stage of a new MRI scanner, this problem must be solved repeatedly for varying model parameters. Thus, in order to optimise this process, the application of Reduced Order Modelling (ROM) techniques is considered. A ROM based on the Proper Orthogonal Decomposition (POD) method is presented.

    The accuracy and efficiency of these methodologies are assessed by applying them to challenging MRI configurations and performing relevant comparisons.