A High Order Finite Element Coupled Multi-Physics Approach To MRI Scanner Design

Bagwell, Scott

doi:10.23889/suthesis.40797

Cited by 1 publication

(32 citation statements)

References 187 publications

(351 reference statements)

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“…This work was based in an Eulerian setting, where the assumption of small displacements and velocities was made. The work was then extended to consider the fully non linear problem in the time domain in [18,17]. The use of hp-finite elements [58,59], as opposed to low-order finite element discretisations, was employed as it is known to enhance the resolution of fine scale features such as small skin depths at high frequencies [114], allow volumetric locking phenomena in nearly incompressible materials to be overcome [170,48,182,86] and improve the resolution of acoustic wave propagation [126].…”

Section: Applications To Mri Scannersmentioning

confidence: 99%

“…The methodology is then applied to challenging MRI configurations including longitudinal as well as transversal gradient coils. Comparisons against the axisymmetric tool developed in [110,19,18,17], commercial software and experimental data are presented to prove the accuracy and efficiency of the method. The main novelty of this chapter is the application of the developed finite element methodology to the numerical simulation of a series of academic and industrially relevant problems, including MRI configurations with longitudinal and transversal gradient coils.…”

Section: Outline Of the Thesismentioning

confidence: 99%

“…denotes the union of N disjoint elastic conducting bodies each with γ ‰ 0 and µ possibly different from µ 0 and Ω c C :" R 3 zΩ C denotes the non-conducting region (Figure 2.2). At the interface between different bodies the electromagnetic and mechanical fields must satisfy some interface or transmission conditions, which can be deduced from the integral form of the governing equations [80,17,73]…”

Section: Interface Conditionsmentioning

confidence: 99%

“…In the following we summarize the main assumptions that led to the Eulerian formulation used in [110,19,18,17] as well as the assumptions that lead to the new Lagrangian formulation [73].…”

Section: Modelling Assumptionsmentioning

confidence: 99%

“…In [110,19,18,17] the coupled magneto-mechanical problem of interest was described using an Eulerian approach, which was based in the following assumptions:…”

Section: Eulerian Formulation For Small Displacements and Velocitiesmentioning

confidence: 99%

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3D simulation of magneto-mechanical coupling in MRI scanners using high order FEM and POD

Seoane¹

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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. Los escáneres de resonancia magnética se han convertido en una herramienta esencial en el sector médico debido a su capacidad de producir imágenes en con alta resolución del cuerpo humano. Para generar una imagen del cuerpo, estos escáneres combinan un fuerte campo magnético estático con gradientes de campo magnético que varían con el tiempo. Los campos magneticos transitorios llevan a la aparici ón de corrientes de Focault en componentes conductores. Estas corrientes, a su vez, a la aparición de una tensión electromagnética, que causan vibraciones y deformaciones en componentes conductores. Estas vibraciones suponen un problema, ya que llevan a un deterioramiento de la calidad de la imagen, así como a la generación de ruido. Las corrientes de Focault, por otro lado, conducen a la disipaci ón de calor en el criostato, que se encuentra relleno de Helio l íquido para mantener las bobinas en un estado superconductor. Esta deposición de calor puede causar la evaporación del Helio y, eventualmente, podría resultar en la pérdida de supercondictividad y, por tanto la interrupci ón del funcionamiento del escáner. Comprender los mecanismos involucrados en la generación de estas vibraciones y del calor depositado en el criostato es, por tanto, imprescindible para lograr un diseño adecuado. Esto requiere de un problema magneto-mecánico acoplado, que es el objetivo de este trabajo. En esta tesis, una nueva metodología basada en elementos finitos de alto orden para la soluci ón de problemas magnetomecánicos tridimensionales, con aplicaci ón al diseño de escáneres de resonancia magnética, es propuesta. Esta metodología resulta en la resolución del problema magneto-mecánico de interés de una forma precisa y eficiente. Sin embargo, en la etapa de diseño de un escáner de resonancia magnética, este problema ha de resolverse de forma repetida variando ciertos parámetros del modelo. Por tanto, para optimizar este proceso, la aplicación de Modelos de Reducción de Orden (ROM) es estudiada. Un ROM basado en el método "Proper orthogonal Decomposition" es presentado. La precisión y eficiencia de estas metodologías es verificada a través de la aplicación de las mismas a diferentes problemas académicos e industrialmente relevantes.

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Section: Applications To Mri Scannersmentioning

confidence: 99%

Section: Outline Of the Thesismentioning

confidence: 99%

Section: Interface Conditionsmentioning

confidence: 99%

“…In the following we summarize the main assumptions that led to the Eulerian formulation used in [110,19,18,17] as well as the assumptions that lead to the new Lagrangian formulation [73].…”

Section: Modelling Assumptionsmentioning

confidence: 99%

“…In [110,19,18,17] the coupled magneto-mechanical problem of interest was described using an Eulerian approach, which was based in the following assumptions:…”

Section: Eulerian Formulation For Small Displacements and Velocitiesmentioning

confidence: 99%

See 3 more Smart Citations

3D simulation of magneto-mechanical coupling in MRI scanners using high order FEM and POD

Seoane¹

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show abstract

A High Order Finite Element Coupled Multi-Physics Approach To MRI Scanner Design

Cited by 1 publication

References 187 publications

3D simulation of magneto-mechanical coupling in MRI scanners using high order FEM and POD

3D simulation of magneto-mechanical coupling in MRI scanners using high order FEM and POD

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