2026-09-20T13:29:12Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/1307112026-06-16T18:56:07Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022
Rajiv Gupta.
Cramer, Avilash(Avilash Kalpathy)
Harvard--MIT Program in Health Sciences and Technology.
Harvard University--MIT Division of Health Sciences and Technology
2021-05-24T19:52:38Z
2021-05-24T19:52:38Z
2021
2021
https://hdl.handle.net/1721.1/130711
1251801720
Thesis: Ph. D., Harvard-MIT Program in Health Sciences and Technology, September, February, 2021
Cataloged from the official PDF version of thesis.
Includes bibliographical references (pages 145-159).
X-ray computed tomography (CT) and planar x-ray imaging are mainstays of modern clinical care. The electron generation mechanism in standard x-ray tubes - specifically, a thermionic cathode - is reliable and capable of high current. However, thermionic cathodes are bulky, and cannot be pulsed quickly. Non-thermionic ('cold-cathode') electron generation can be exploited to make a smaller and rapidly pulsable x-ray source. Such an x-ray source could improve not just the portability of x-ray devices, but would allow for a CT system to operate by pulsing a distributed ring of x-ray sources instead of rotating a single large x-ray source. Furthermore, cold-cathode x-ray sources could allow for new signal acquisition and processing paradigms in the x-ray domain. This includes time-based image acquisition techniques, such as elastography and photon-counting measurements. In this dissertation, I discuss (1) the development of two novel types of cold-cathode x-ray sources: an ultraviolet photocathode-based source, and a silicon field emission chip; (2) novel methods for planar x-ray image acquisition, including a demonstration of dynamic x-ray elastography using a pulsed photocathode x-ray source; and (3) applications of modern signal processing techniques to the tomographic image reconstruction problem. In an epilogue, I discuss our research on N95 respirator sterilization and re-use for crisis situations.
by Avilash Cramer.
Ph.D.
Ph.D. Harvard-MIT Program in Health Sciences and Technology
159 pages
eng
Massachusetts Institute of Technology
MIT theses may be protected by copyright. Please reuse MIT thesis content according to the MIT Libraries Permissions Policy, which is available through the URL provided.
http://dspace.mit.edu/handle/1721.1/7582
Harvard--MIT Program in Health Sciences and Technology.
Design and applications of cold-cathode X-ray imaging systems
Thesis
application/pdf
2021-05-24T19:52:38Z
Publication
Doctoral
HST
unknown
unknown
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<Abstract>X-ray computed tomography (CT) and planar x-ray imaging are mainstays of modern clinical care. The electron generation mechanism in standard x-ray tubes - specifically, a thermionic cathode - is reliable and capable of high current. However, thermionic cathodes are bulky, and cannot be pulsed quickly. Non-thermionic ('cold-cathode') electron generation can be exploited to make a smaller and rapidly pulsable x-ray source. Such an x-ray source could improve not just the portability of x-ray devices, but would allow for a CT system to operate by pulsing a distributed ring of x-ray sources instead of rotating a single large x-ray source. Furthermore, cold-cathode x-ray sources could allow for new signal acquisition and processing paradigms in the x-ray domain. This includes time-based image acquisition techniques, such as elastography and photon-counting measurements. In this dissertation, I discuss (1) the development of two novel types of cold-cathode x-ray sources: an ultraviolet photocathode-based source, and a silicon field emission chip; (2) novel methods for planar x-ray image acquisition, including a demonstration of dynamic x-ray elastography using a pulsed photocathode x-ray source; and (3) applications of modern signal processing techniques to the tomographic image reconstruction problem. In an epilogue, I discuss our research on N95 respirator sterilization and re-use for crisis situations.</Abstract>
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