Performance of a carbon nanotube field emission X-ray source array for stationary digital breast tomosynthesis Public Deposited

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  • March 19, 2019
Creator
  • Gidcumb, Emily
    • Affiliation: College of Arts and Sciences, Department of Applied Physical Sciences, Materials Science Graduate Program
Abstract
  • This work describes the performance of a stationary digital breast tomosynthesis (s-DBT) X-ray tube based on carbon nanotube (CNT) cathodes, and the imaging system developed around it. The s-DBT system has the potential to improve the detection and diagnosis of breast cancer over commercially available digital breast tomosynthesis (DBT) systems. DBT is growing in popularity in the United States, and around the world, as a potential replacement for traditional 2D mammography. The main advantage of DBT over 2D mammography lies in the pseudo-3D nature of the technique allowing the removal of overlapping breast tissue within the image. s-DBT builds on this advantage by removing blur from focal spot motion. Introductions to breast imaging techniques and the DBT modality are given, followed by an introduction to carbon nanotube field emission, the foundation of the s-DBT technology. Details of the s-DBT X-ray tube design and system integration are discussed including specific design parameters, system requirements, and the development process. Also included are summaries of the X-ray tube and system performance over time, and results from characterization measurements. Specific focus is given to the development and completion of a fabrication procedure for tungsten gate mesh, characterization of the CNT cathodes, and improving the system's spatial resolution with use of the focusing electrodes. The tungsten gate mesh is an essential component for extracting electrons from CNTs. A successful deep reactive ion etching fabrication procedure was developed, and the improved gate mesh allowed for higher cathode current and longer pulse widths to be employed in the s-DBT system. Characterization of the CNT cathodes revealed their high-current capacity and the ability to produce relatively long pulse widths, mimicking a 2D imaging modality. This work confirmed that the cathodes are well suited for the task of breast imaging, and explored possible improvements. Lastly, it was shown that by employing and optimizing the focusing electrodes, spatial resolution of the s-DBT system improved, with a tradeoff in loss of transmission rate. This work has contributed to the development and evaluation of the s-DBT technology from the laboratory research stage through clinical trials on human tissue and patients.
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  • In Copyright
Advisor
  • Kleinhammes, Alfred
  • Washburn, Sean
  • Lu, Jianping
  • Lee, Yueh
  • Zhou, Otto
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2014
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  • Chapel Hill, NC
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