Thesis: Ph. D. in Medical Engineering, Harvard-MIT Program in Health Sciences and Technology, 2017. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 99-108). / Non-invasive imaging plays an important role throughout the clinical diagnosis and management process of breast cancer. Unfortunately, existing imaging methods lack the combination of spatial resolution and soft-tissue contrast necessary to visualize pathological changes in the breast. X-ray phase-contrast imaging (XPCI) has emerged as a promising modality for providing enhanced soft tissue differentiation due to its inherent source of contrast being derived from diffraction effects rather than absorption. Studies using synchrotron sources have demonstrated the potential of XPCI in revealing structural details of the breast undetectable via existing modalities. However, the reliance on high-brilliance synchrotron sources significantly limits the use of XPCI in medical applications. In this thesis, we address this challenge by developing a compact XPCI system compatible with low-brilliance laboratory sources that retrieves phase from free-space propagation. We further combine quantitative phase imaging with computed tomography (CT) which enables us to investigate internal structures in 3D. Existing techniques for phase retrieval either require images to be acquired at multiple defocus planes, or assumptions to be made that do not hold true for many objects of interest. To address these limitations, we developed an iterative algorithm for phase retrieval using images acquired at two different energies. Our results show that this algorithm retrieves phase more accurately than existing methods. Finally, we illustrate the potential utility of our compact XPCI system in visualizing pathological features by imaging transgenic mouse models of breast cancer. These pre-clinical results show that phase CT is able to clearly distinguish tumor masses whereas the same features imaged using commercial microCT are obscured by noise. Overall, the methods developed in this thesis provide a proof of concept for conducting tomographic XPCI outside of synchrotron facilities, thus paving the way towards future clinical implementation. / by Ling Xu. / Ph. D. in Medical Engineering
| Identifer | oai:union.ndltd.org:MIT/oai:dspace.mit.edu:1721.1/111311 |
| Date | January 2017 |
| Creators | Xu, Ling, Ph. D. Massachusetts Institute of Technology |
| Contributors | George Barbastathis., Harvard--MIT Program in Health Sciences and Technology., Harvard--MIT Program in Health Sciences and Technology. |
| Publisher | Massachusetts Institute of Technology |
| Source Sets | M.I.T. Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 108 pages, application/pdf |
| Rights | MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission., http://dspace.mit.edu/handle/1721.1/7582 |
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