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Full-Text Articles in Medical Specialties
Phase And Dark Field Radiography And Ct With Mesh-Based Structured Illumination And Polycapillary Optics, Uttam Pyakurel
Phase And Dark Field Radiography And Ct With Mesh-Based Structured Illumination And Polycapillary Optics, Uttam Pyakurel
Legacy Theses & Dissertations (2009 - 2024)
Imaging can be performed with a variety of techniques. For example, gamma radiation is used in nuclear medicine and radiation therapy A challenge in using gamma rays is the risk of high radiation exposure, which requires extensive custom shielding. The transmission of gamma rays through 3D printed shielding was measured to evaluate the required thickness of the shielding.Conventional radiography depends on x-ray attenuation. Another imaging technique, X-ray phase imaging, is known to improve the contrast of images relative to conventional imaging for low density materials. Phase differences imparted by soft tissue are roughly 1000 times larger than attenuation differences. Further, …
Therapy And Medical Imaging Applications Of Focusing Polycapillary X-Ray Optics, Weiyuan Sun
Therapy And Medical Imaging Applications Of Focusing Polycapillary X-Ray Optics, Weiyuan Sun
Legacy Theses & Dissertations (2009 - 2024)
Focusing polycapillary optics yield high gains in intensity and increased spatial resolution for a variety of clinical, lab-based, synchrotron, or in situ analysis applications. In this dissertation we investigate the extension of two applications of focusing polycapillary optics. The first is the application of polycapillary optics in radiation therapy. This discussion includes measurements and calculation of dose for focused beam orthovoltage therapy. A system has been designed to investigate whether the polycapillary optics can produce an X-ray beam which can give more accurate dose painting due to the higher dose concentration at the focal spot. X-ray exposures were measured with …
Phase Imaging Using Focusing Polycapillary Optics, Sajid Bashir
Phase Imaging Using Focusing Polycapillary Optics, Sajid Bashir
Legacy Theses & Dissertations (2009 - 2024)
The interaction of X rays in diagnostic energy range with soft tissues can be described by Compton scattering and by the complex refractive index, which together characterize the attenuation properties of the tissue and the phase imparted to X rays passing through it. Many soft tissues exhibit extremely similar attenuation, so that their discrimination using conventional radiography, which generates contrast in an image through differential attenuation, is challenging. However, these tissues will impart phase differences significantly greater than attenuation differences to the X rays passing through them, so that phase-contrast imaging techniques can enable their discrimination.
Application Of X-Ray Diffraction To Material Analysis And Medical Imaging, Wei Zhou
Application Of X-Ray Diffraction To Material Analysis And Medical Imaging, Wei Zhou
Legacy Theses & Dissertations (2009 - 2024)
Powder diffraction is commonly used to determine the structures of both inorganic and organic materials. The angle and intensity of the diffraction (also called coherent scatter) peak depends on the nanostructure of the material. When no x-ray optic is used, the peak width broadens, and hence the resolution worsens, as the sample area is increased. However, a small sample area gives low diffracted signal intensity, particularly for thin films and for organic materials, which have low diffraction cross sections. X-ray optics can be used in x-ray powder diffraction to increase the diffraction intensity, thus decreasing exposure times. For a small …