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Full-Text Articles in Physics
Mesh And Diffraction-Based X-Ray Phase Imaging, Congxiao He
Mesh And Diffraction-Based X-Ray Phase Imaging, Congxiao He
Legacy Theses & Dissertations (2009 - 2024)
More than a hundred years have passed since X-rays were detected by Wilhelm Rontgen. Due to their properties, they soon became widely applied in many areas, especially medical imaging. Recently, many new X-ray imaging techniques were designed, including phase imaging and diffraction enhanced imaging, DEI.
Mesh-Based Fourier Imaging For Biological And Security Applications, Danielle Justine Hayden
Mesh-Based Fourier Imaging For Biological And Security Applications, Danielle Justine Hayden
Legacy Theses & Dissertations (2009 - 2024)
Traditional x-ray imaging provides only low contrast from low atomic number materials, like soft tissue, due to the small attenuation variations producing very small intensity changes. Higher contrast can be achieved through phase information. The phase change is obtained from the x-ray refracting in a sample, or phase object, due to the difference in refractive indexes. This causes a small angular deviation from the original path. Phase contrast imaging has not been realized in everyday practice due to the requirement for large spatial coherence width of the x-ray beam which typically requires sources on the order of 10-50 m, the …
Coherent Scatter And Grid-Based Phase Imaging For Materials Discrimination, Sean Niccholas Starr-Baier
Coherent Scatter And Grid-Based Phase Imaging For Materials Discrimination, Sean Niccholas Starr-Baier
Legacy Theses & Dissertations (2009 - 2024)
Traditional X-Ray images provide a meaningful way to differentiate between materials with differing attenuation coefficients. The low contrast provided by this method for materials of low electron density or similar attenuation is a limitation of traditional radiography. Two alternatives have presented themselves as viable candidates for widening the viability of X-Ray imaging, Coherent scatter, and phase contrast imaging provide a means to distinguish between objects of both low absorption and similar attenuation.
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 …
Phase Imaging Using X-Ray Optics, Bushra Kanwal
Phase Imaging Using X-Ray Optics, Bushra Kanwal
Legacy Theses & Dissertations (2009 - 2024)
Conventional x-ray imaging is a widely used imaging technique in medical diagnostics as well as material analysis. It utilizes only absorption-contrast imaging, which records intensity attenuation due to absorption. A major limitation of this technique for medical imaging is the poor contrast of weakly absorbing details in the soft tissue. Mammography and angiography are two examples where improved contrast is required. In the quest for better contrast in x-ray imaging, a number of different phase contrast imaging techniques have been explored. Phase contrast imaging offers an improvement over traditional absorption contrast because the x-ray wave field traversing an object experiences …