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 20 of 20 for “"X-ray beams"”.
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The effect of intense x-ray beams on oxide glasses unveiled by means of photon correlation spectroscopy
… we aim to study the structural evolution under x-ray illumination in a selection of oxide glass formers as a function of the radiation dose. The irradiated specimens are investigated by means of XPCS experiments and also by means of “exsitu” experiments as luminescence, Raman and x-ray diffraction …
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Dosimetric characterization of a miniature x-ray source for biophysics studies
… this project it is proposed to use a miniature X-Ray source (Mini-X) to simulate tritium radiation and characterise these low energy X-Ray beams with the aim of investigating the relative biological effectiveness of low energy electrons. The scope of this study is to design and characterize low …
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Microscopy of Gold Microcrystals by Coherent X -Ray Diffractive Imaging
"The small wavelength and penetrating nature of X-ray radiation has long been used to solve the structure of materials. Inherent in these measurements is the loss of phase information in the intensity measurement; the so-called ""phase problem."" Third generation synchrotrons provide X-ray beams …
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Iterative Reconstruction Algorithms for Polyenergetic X-ray Computerized Tomography
… on a polyenergetic model. While most modern x-ray CT scanners rely on the well-known filtered back-projection algorithm, the corresponding reconstructions can be corrupted by beam hardening artifacts. These artifacts arise from the unrealistic physical assumption of monoenergetic x-ray beams. …
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Design of an Ytterbium-169 brachytherapy source for gold nanoparticle-aided radiation therapy
… simulations have demonstrated that the gamma-ray energy spectrum of Ytterbium-169 is a strong candidate for a high dose rate brachytherapy implementation of gold nanoparticle-aided radiation therapy. Therefore, the current study focuses on the design of a high dose rate Ytterbium-169 source …
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Application of precision engineering for nanometre focussing of hard X-rays in synchrotron beam lines
… modern synchrotron beamlines are able to focus X-rays to a few microns in size. Although the technology to achieve this is well established, performing routine experiments with such beams is still time consuming and requires careful set up. Furthermore there is a need to be able to carry out …
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Penumbral Distributions For High-energy Radiotherapy Photon Beams: Experimental And Theoretical Determinations
… electron density for Co-60, 6- and 31-MV x-ray beams. The results indicate that the measured penumbral dose distributions must be corrected for the inside diameter of the ionization chamber. The penumbral primary dose distributions in lung-equivalent media are significantly broader than …
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Automatic image alignment for clinical evaluation of patient setup errors in radiotherapy
… by irradiating the patient with high energy x-ray beams conformed to the shape of the tumour from multiple directions. Rather than administering the total dose in one session, the dose is often delivered in twenty to thirty sessions. For each session several settings must be reproduced …
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Sviluppo di un tomografo multi-energy per lo studio pre-clinico di nuove metodiche diagnostiche finalizzate al riconoscimento precoce della patologia tumorale
… makes use of a set of quasi-monochromatic X-ray beams, with energy tunable in a range from 26 KeV to 72 KeV. These beams are produced by Bragg diffraction on a Highly Oriented Pyrolytic Graphite crystal. With quasi-monochromatic sources it is possible to perform multi-energy investigation in …
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Mejora de un código hidrodinámico con transporte de radiación en malla adaptativa refinada (AMR) y su aplicación a los láseres de rayos X
… with gas amplifiers demonstrated high quality X ray beams. Since amplifiers based on solid targets are denser than those generated from gas, higher energy and shorter pulse durations were expected. However, experiments demonstrated lower energy around 90 nJ and slightly shorter pulse duration …
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Development of Serial Crystallography Methods for Synchrotrons and X-ray Free-Electron Lasers
X-ray crystallography of proteins is a well-established method to identify atomic level molecular arrangement, however when exposing crystalline proteins to ionising radiation, damage can occur to their overall molecular structure (global damage), while solvated electrons generated by X-rays can …
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Point-based Ionizing Radiation Dosimetry Using Radiochromic Materials and a Fibreoptic Readout System
… media was tested over 75 kVp – 18 MV range of x-ray beams. The optical density measured for EBT was constant within 3% throughout the entire range, while MD-55 exhibited a nearly 40% decrease at low energies. Both materials were also shown to be temperature sensitive, with the change in optical …
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Development of A New Independent Monte Carlo Dose Calculation Quality Assurance Audit to ol For Clinical Trials
… Filter Free (FFF) 6MV and FFF 10MV therapeutic x-ray beams were developed. The Monte Carlo technique, using the Dose Planning Method (DPM) algorithm, was used in radiation dose calculations. During validation calculations were compared to open field measurements in a water phantom. Benchmarking …
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Nanofocusing Refractive X-Ray Lenses
… of the production of nanofocusing refractive x-ray lenses. These optics made of either silicon or diamond are well-suited for high resolution x-ray microscopy. The goal of this work is the design of a reproducible manufacturing process which allows the production of silicon lenses with high …
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Monte Carlo Analysis and Physics Characterization of a Novel Nanoparticle Detector for Medical and Micro-dosimetry Applications
… in a cylindrical mouse phantom at 225 kV for x-ray irradiation at angles of 0, 90, 180, and 270˝. The NanoFOD exhibited small changes in angular sensitivity, with a coefficient of variation (COV) of 3.6% at 120 kV and 1% at 225 kV. When the NanoFOD was placed alongside a MOSFET in the liver of a …
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TOMOGRAPHIC IMAGE RECONSTRUCTION: IMPLEMENTATION, OPTIMIZATION AND COMPARISON IN DIGITAL BREAST TOMOSYNTHESIS
… scanning time than a conventional digital X-ray modality and a low spatial resolution due to the movement of the single X-ray source. Dr.Otto Zhou's group proposed the concept of stationary digital breast tomosynthesis (s-DBT) using a Carbon Nano-Tube (CNT) based X-ray source array. Instead …
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Cellular metal ion sensing using DNAzymes
… bound and mobile forms. Techniques based on X-ray absorption, such as X-ray fluorescence microscopy (XFM) can simultaneously detect multiple metal ions and can distinguish between different oxidation states. However, these techniques require the use of highly focused X-ray beams limiting more …
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Microfluidics at high-intensity X-ray sources: from microflow chips to microfluidic liquid jet systems
… for fundamental investigations at microfocused X-ray sources. With recent developments in synchrotron technology and with the advent of free electron lasers (FEL), very exciting possibilities arise, such as serial femtosecond X-ray nanocrystallography. This on-going technological progress also …
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Radiation biophysical modeling of the FLASH effect: from mechanistic understanding towards clinical endpoint prediction
… The FLASH effect has been seen using proton beams, where the loss of proliferating cells in intestinal crypts or the acute skin damage and radiation-induced fibrosis was reduced at FLASH regime with respect to Conv, for the same tumor control. Lastly, this effect has been confirmed with ions, …