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Digital X-ray deformation and phase-contrast imaging
2002 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

In this work a method that detects and measures deformations inside objects, that are opaque to visible light, is presented. Images with high spatial resolution, due to the use of a microfocus x-ray source and a high resolving solid state detector, are captured showing the interior of the opaque object. Here, the deformation process inside a biological sample is studied. By collecting two images, one before and one after a deformation process, and applying a Digital Speckle Photography (DSP)-program to these a displacement field, that describe the deformation, is calculated. This method does not require any use of contrast agents, that provide enhanced contrast in the images. The use of such contrast agents often imply influence on the sample, which is undesirable. A method to obtain information coded in the phase of the x-rays is investigated as well. This method is based on properties of free-space propagation of light in the Fresnel zone where phase information is translated to visual intensity information, provided a sufficient distance of propagation. More explicitly, this phase-intensity relationship is described by the Transport of Intensity Equation, which is used to retrieve the phase distribution of the light numerically from measurements of the intensity distribution in two image planes. An algorithm that solves the equation, for the case where the intensity distribution is uniform in the object plane, is implemented and its performance is investigated through a simulation.

Place, publisher, year, edition, pages
Keyword [en]
Technology, X-ray, digital speckle photography, radiography, deformation, displacement field, phase-contrast, transport of intensity, equation, numerical phase retrieval
Keyword [sv]
URN: urn:nbn:se:ltu:diva-45932ISRN: LTU-EX--02/142--SELocal ID: 39232ac7-12ea-477e-8f5c-74a21622c572OAI: diva2:1019239
Subject / course
Student thesis, at least 30 credits
Educational program
Engineering Physics, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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