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Exploring the Capabilities of Computed Tomography with Bent Laue Crystal Optics

Date

2024-07-08

Journal Title

Journal ISSN

Volume Title

Publisher

ORCID

0009-0007-9760-3228

Type

Thesis

Degree Level

Doctoral

Abstract

This research aims to explore novel uses of bent Laue crystals as x-ray optics to extend the capabilities of computed tomography (CT) at synchrotron facilities. Firstly, we demonstrate the ability to manipulate a beam’s size, maintaining a parallel beam, by “compressing” it horizontally using a pair of cylindrically bent Laue crystals. This compressed beam creates a desirable aspect ratio for CT of small samples. In contrast to collimation of the beam, this compressor “funnels” a large section of the beam’s flux into a smaller imaging area, significantly raising intensity and allowing users to work in the gap between bend magnet (BM) and insertion device (ID) beamline intensities. Secondly, we demonstrate a fan-beam version of the compressor using a single crystal, greatly reducing setup time and complication. This fan-beam version provides a virtually unlimited variation in compression of the beam by adjusting sample location. We have demonstrated its capacity for CT of multiple small samples. Reconstruction is by fan-beam methods commonly used in clinical CT. Thirdly, we have leveraged the spectral nature of the compressed beam to gather additional information about the sample, based on the change in attenuation relative to x-ray energy. We demonstrate the application of k-edge subtraction to CT scans using the compressed beam, as well as the ability to capture the attenuation curves of material samples for material identification. Finally, we demonstrate a CT imaging method that images a single slice of a sample while simultaneously capturing the energy attenuation curve of every pixel at every energy in the beam. The energy range of the data easily reaches 40 keV. Furthermore, we apply material decomposition algorithms to this energy attenuation curve to provide the concentration of each of the materials in each pixel of the reconstructed CT slice. While further development of these systems is needed, we demonstrate here the proof-of-principle of these optical systems. These systems will increase the capabilities of CT at synchrotron facilities by allowing more flexibility in the intensity of BM beamlines and allowing for the extraction of attenuation curves, simultaneous to imaging, through use of spectral beams.

Description

Keywords

imaging, computed tomography, hyperspectral, spectral, x-ray, laue, crystal, focusing, synchrotron, bend magnet, canadian light source, compressor, optics, collimation, insertion device, beamline, energy,

Citation

Degree

Doctor of Philosophy (Ph.D.)

Department

Biomedical Engineering

Program

Biomedical Engineering

Citation

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DOI

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