Novel 3D Ultrasound Imaging Techniques Using Top-Orthogonal-to-Bottom-Electrode (TOBE) Arrays

• Author / Creator

  Christopher Ceroici

• Ultrasound imaging is a safe, affordable and reliable diagnostic tool widely used in medical professions. While 2D ultrasound imaging is used extensively in clinical environments, 3D ultrasound imaging has not yet seen wide clinical acceptance. This is partly due to the practical limitations on the design of 2D ultrasound arrays. Due to system constraints on the number of channels an ultrasound probe can have, fully-connected 2D arrays are often limited in size, resulting in a small numerical aperture with weak focusing power and thus poor image quality. Techniques such as multiplexing and backside electronics have been used to circumvent this problem, however, these approaches often compromise on image quality or result in large, bulky probes requiring liquid cooling. This thesis describes several 3D imaging techniques utilizing Top-Orthogonal-to-Bottom-Electrode (TOBE) arrays. These 2D arrays use a row-column connection scheme to reduce the required number of channels yet maintain the ability to address individual elements in the array.
  TOBE imaging schemes are outlined for both ultrasound and photoacoustic imaging applications. The Fast Orthogonal to Row-Column Electronic Scanning (FORCES) imaging scheme is an 3D ultrasound imaging schemes which combines high-quality 2D imaging performance with 3D imaging capabilities. Using this technique, experimental results are compared with a linear array of similar size. Hadamard-encoded TOBE photoacoustic imaging is an imaging scheme used to acquire 3D volumetric data from photoacoustic signals using TOBE arrays. Unlike previous TOBE photoacoustic imaging schemes, this approach allows for the array to receive across the entire 2D aperture simultaneously resulting in substantially improved SNR. Both imaging techniques are demonstrated with wire-phantom 3D imaging experiments where resolution and SNR measurands are compared. Finally, the combination of FORCES, Hadamard-encoded TOBE photoacoustic, as well as a power Doppler imaging is used to demonstrate multimodal imaging of blood flowing in a tube, imitating a blood vessel. This experiment demonstrates the 3D acquisition of acoustic, flow, and optical contrast using the same array and experimental setup.
  Capacitive micromachines ultrasonic can be used as an alternative to piezoelectric/electrostrictive transducers and offer the potential of higher sensitivity. The simulation and design of 2D array CMUT transducers is performed with the goal of minimizing transducer element crosstalk and maximizing transmit power, sensitivity and by extension, reconstructed image quality. This model is coupled with an acoustic field simulator, bridging the gap between the simulation of the design and the imaging array.

• Subjects / Keywords

  • Ultrasound
  • Beamforming
  • Medical Imaging
  • Biomedical Engineering

• Graduation date

  Fall 2019

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-05bs-7730

• License

  Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.