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Title: Application of X-ray phase imaging in the estimation of tissue optical scattering
Author: Maughan Jones, Charlotte Joanna
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2019
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The ability to non-invasively estimate the optical properties of biological tissues in vivo would enable the advancement of quantitative optical based techniques such as photoacoustic imaging. It has, to date, proven difficult to make such an estimation for large three-dimensional tissue sections and small animals using optical approaches. To overcome this limitation, the correlation between the optical scattering properties, and the dark field x-ray phase contrast (XPCi), or 'x-ray scattering' signal has been investigated. To do this, phantoms with unknown x-ray scattering, but controlled optical scattering were designed, and manufacturing methods developed, to enable simultaneous manufacture of phantoms suitable for either x-ray or optical imaging. Phantoms consisted of agarose, gel wax or silicone embedded with either TiO2 powder or silica microspheres. The x-ray phantoms were imaged using the edge illumination (EI) system at UCL. Due to the very low scattering and high absorption of many of the samples, along with the imperfect absorption of the masks in the EI system, existing scatter retrieval methods were unable to accurately determine the scattering properties of the phantoms. A novel, more sensitive x-ray scatter retrieval method was thus developed to overcome these problems. The optical scattering of phantoms was retrieved using a spectrophotometer combined the inverse adding doubling method. The optical and x-ray scattering of the phantoms was thus compared which did not reveal any correlation between the two. In order to assess a correlation between optical and x-ray scattering in biological tissue, Optical coherence tomography (OCT) was investigated as a method of determining the optical scattering properties. Along with the use of a controlled 'calibration phantom', the optical properties of such tissues were determined. Finally, biological tissue samples were imaged using both OCT and EI-XPCi, and the optical and x-ray scattering properties compared, with no correlation observed.
Supervisor: Munro, P. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available