Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 9 of 9 for “"Beam hardening"”.
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Automated Modelling of Cortical Bone from Clinical CT
… for inaccuracies in CBM measurements caused by beam hardening effects to be considered for the first time: I show that beam hardening leads to an underestimation in cortical thickness and an overestimation in trabecular BMD and that these inaccuracies can be reduced through adjustments to the …
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Measurement of neutron radiotherapy spectra in a tissue-equivalent phantom
… to give the neutron spectra. The results show beam hardening with depth into the phantom, which are consistent with other reported findings. The unfolding procedures used are described and the results of the tests performed to verify reliability are also presented and discussed.
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Iterative Reconstruction Algorithms for Polyenergetic X-ray Computerized Tomography
… reconstructions can be corrupted by beam hardening artifacts. These artifacts arise from the unrealistic physical assumption of monoenergetic x-ray beams. In this thesis, to compensate, we use an alternative model that accounts for differential absorption of polyenergetic x-ray …
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Improving ion beam therapy treatment planning for metal implants by using dual-energy CT scanning
One of the major uncertainties in ion beam therapy planning is the calculation of ion ranges in the patient’s tissue from CT images. The presence of non-tissue-equivalent mate- rials and materials with high photon attenuation like metals may aggravate this problem. Dual Energy Computed Tomography …
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Photoproduction of charged pions from deuterium near threshold
… section near threshold. To do this an X=ray beam from the University of Illinois betatron was passed through a 14 inch liquid deuterium bubble chamber. Each X ·-ray pulse (E max :: 230 MeV) contained a total energy of about 106 MeV. l'ne X.""ray beam wa.s hardened by means of a. standard beam …
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Comparative imaging of the canine acute abdomen: survey radiography, contrast-enhanced ultrasound and contrast-enhanced multi-detector helical computed tomography
… diagnostic scans were attributed to severe beam hardening from previously administered barium contrast agent and severe motion artifacts. The results of this study suggest that dual-phase CE-MDCT is a feasible and safe technique for evaluating awake and minimally sedated dogs presenting with …
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Development of a Fast X-ray Line Detector System for Two-Phase Flow Measurement
Measuring void fraction distribution in two-phase flow has been a challenging task for many decades because of its complex and fast-changing interfacial structure. In this study, a non-intrusive X-ray measurement system is developed and calibrated to mitigate this challenge. This approach has …
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Dual Energy Computed to mography For Proton Therapy Treatment Planning
… us from realizing the full potential of proton beams. Therefore, it is critical to reduce uncertainties in the proton radiation therapy.</p> <p>One major uncertainty in a proton treatment is the range uncertainty related to the estimation of proton stopping power ratio (SPR) distribution inside …
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Imaging Techniques for Proton Range Determination in Proton Therapy
… (up to 0.5% to 1.8% of the total proton beam range), SECT uncertainty (beam hardening, reconstruction artifacts, etc.), and patient positioning uncertainty (misalignment, motions, and anatomical changes). Two emerging techniques have been proposed to improve proton SRP estimation accuracy …