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Full-Text Articles in Physics
System Measurements For X-Ray Phase And Diffraction Imaging, Erik Wolfgang Tripi
System Measurements For X-Ray Phase And Diffraction Imaging, Erik Wolfgang Tripi
Legacy Theses & Dissertations (2009 - 2024)
In medical imaging, X rays are used to look inside the body to find fractures in bones, abnormal masses, cavities in teeth, and so on. What makes X rays so good at looking at these types of structures is the X ray’s penetration power. When imaging soft tissue to search for tumors, X-ray images tend to have difficulty performing well. The reason for this is that the background structures, such as fat or fibro glandular tissue have similar absorption coefficients as the tumor. Mammography tends to have a high false positive rate and can miss tumors entirely as well. There …
Grid-Based Fourier Transform Phase Contrast Imaging, Sajjad Tahir
Grid-Based Fourier Transform Phase Contrast Imaging, Sajjad Tahir
Legacy Theses & Dissertations (2009 - 2024)
Low contrast in x-ray attenuation imaging between different materials of low electron density is a limitation of traditional x-ray radiography. Phase contrast imaging offers the potential to improve the contrast between such materials, but due to the requirements on the spatial coherence of the x-ray beam, practical implementation of such systems with tabletop (i.e. non-synchrotron) sources has been limited. One recently developed phase imaging technique employs multiple fine-pitched gratings. However, the strict manufacturing tolerances and precise alignment requirements have limited the widespread adoption of grating-based techniques. In this work, we have investigated a technique recently demonstrated by Bennett et al.1 …
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 …