Spectral Signature and Correction of Scattered Radiation in Energy-Resolved X-ray Imaging

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dc.contributor.advisorDas, Mini
dc.contributor.committeeMemberGifford, Howard C.
dc.contributor.committeeMemberKoerner, Lisa W.
dc.contributor.committeeMemberVarghese, Oomman K.
dc.creatorLewis, Cale E.
dc.date.accessioned2021-08-06T19:34:06Z
dc.date.createdDecember 2020
dc.date.issued2020-12
dc.date.submittedDecember 2020
dc.date.updated2021-08-06T19:34:08Z
dc.description.abstractX-ray imaging is a powerful tool for material identification and characterization with applications in a wide range of fields including medicine, biology, geoscience, and security. Since the discovery of x-rays in 1895, gradual improvements to imaging technology have lead to some major milestones such as computed tomography (CT). More recently, pioneering advancements in x-ray detector technology have made possible photon counting detectors (PCDs) with energy-resolving capabilities. Exploiting spectral information of the incident radiation promises revolutionary approaches to material identification and characterization. However, radiation that scatters from the object and reaches the detector is a long-standing problem that reduces image quality and quantitative accuracy. Previous studies to characterize and account for the scattered radiation have been limited to conventional x-ray imaging with energy-integrating detectors (EIDs). The purpose of this research is two-fold: i) determine the spectral characteristics of the scattered radiation and the impact on quantitative spectral imaging and ii) develop an energy-sensitive scatter correction method to compensate for these inaccuracies. Through Monte Carlo simulation and experimental validation, the spectral characteristics of scatter are evaluated for a large scope of imaging parameters including: the object geometry and composition, object-to-detector distance, x-ray source distribution, and detector type. The impact of the scattered radiation was evaluated by estimating the energy-dependent attenuation properties of clinically-relevant materials. When left uncorrected, scattered radiation results in severe quantitative inaccuracies which can limit proper material identification. The next objective was applying these characteristics to develop an energy-sensitive scatter correction that compensates for the inaccuracies due to scatter. Our method derives from the physical understanding of scatter interactions to estimate the spectrally-dependent scatter maps. This method was applied in the context of contrast-enhanced mammography, which showed accurate quantitative restoration of iodine targets in breast-like phantoms. This particular scatter correction technique is appealing as it does not require any modifications to the acquisition process or beam path. The versatility of the energy-sensitive scatter estimation technique also suggests further utility in other x-ray imaging applications such as tomosynthesis and computed tomography.
dc.description.departmentPhysics, Department of
dc.format.digitalOriginborn digital
dc.format.mimetypeapplication/pdf
dc.identifier.citationPortions of this document appear in: Lewis, Cale E., and Mini Das. "Spectral signatures of X-ray scatter using energy-resolving photon-counting detectors." Sensors 19, no. 22 (2019): 5022.
dc.identifier.urihttps://hdl.handle.net/10657/8028
dc.language.isoeng
dc.rightsThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. UH Libraries has secured permission to reproduce any and all previously published materials contained in the work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).
dc.subjectSpectral x-ray
dc.subjectX-ray scatter
dc.subjectPhoton counting detectors
dc.titleSpectral Signature and Correction of Scattered Radiation in Energy-Resolved X-ray Imaging
dc.type.dcmiText
dc.type.genreThesis
local.embargo.lift2022-12-01
local.embargo.terms2022-12-01
thesis.degree.collegeCollege of Natural Sciences and Mathematics
thesis.degree.departmentPhysics, Department of
thesis.degree.disciplinePhysics
thesis.degree.grantorUniversity of Houston
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy

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