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Emre, Eylem. "Scanning Imaging With High Energy Photons". Master's thesis, Ankara : METU, 2003. http://etd.lib.metu.edu.tr/upload/1206614/index.pdf.
Pełny tekst źródłaBrink, Paul Louis. "Non-equilibrium superconductivity induced by X-ray photons". Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260725.
Pełny tekst źródła梁邦平 i Pong-ping Leung. "High energy photons from accretion powered X-ray binaries". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1993. http://hub.hku.hk/bib/B31233727.
Pełny tekst źródłaLeung, Pong-ping. "High energy photons from accretion powered X-ray binaries /". [Hong Kong : University of Hong Kong], 1993. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13829853.
Pełny tekst źródłaFarquharson, Michael James. "Characterisation of bone tissue using coherently scattered x-ray photons". Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243790.
Pełny tekst źródłaSu, Ting. "Quantitative material decomposition methods for X-ray spectral CT". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI056/document.
Pełny tekst źródłaX-ray computed tomography (X-ray CT) plays an important part in non-invasive imaging since its introduction. During the past few years, numerous technological advances in X-ray CT have been observed, including spectral CT, which uses photon counting detectors (PCDs) to discriminate transmitted photons corresponding to selected energy bins in order to obtain spectral information with one single acquisition. Spectral CT enables us to overcome many limitations of the conventional CT techniques and opens up many new application possibilities, among which quantitative material decomposition is the hottest topic. A number of material decomposition methods have been reported and different experimental systems are under development for spectral CT. According to the type of data on which the decomposition step operates, we have projection domain method (decomposition before reconstruction) and image domain method (decomposition after reconstruction). The commonly used decomposition is based on least square criterion, named proj-LS and ima-LS method. However, the inverse problem of material decomposition is usually ill-posed and the X-ray spectral CT measurements suffer from Poisson photon counting noise. The standard LS criterion can lead to overfitting to the noisy measurement data. In the present work, we have proposed a least log-squares criterion for projection domain method to minimize the errors on linear attenuation coefficient: proj-LLS method. Furthermore, to reduce the effect of noise and enforce smoothness, we have proposed to add a patchwise regularization term to penalize the sum of the square variations within each patch for both projection domain and image domain decomposition, named proj-PR-LLS and ima-PR-LS method. The performances of the different methods were evaluated by spectral CT simulation studies with specific phantoms for different applications: (1) Medical application: iodine and calcium identification. The decomposition results of the proposed methods show that calcium and iodine can be well separated and quantified from soft tissues. (2) Industrial application: ABS-flame retardants (FR) plastic sorting. Results show that 3 kinds of ABS materials with different flame retardants can be separated when the sample thickness is favorable. Meanwhile, we simulated spectral CT imaging with a PMMA phantom filled with Fe, Ca and K solutions. Different acquisition parameters, i.e. exposure factor and number of energy bins were simulated to investigate their influence on the performance of the proposed methods for iron determination
Galarowicz, Dale. "Instrumentation requirements for TREE Effects Data Collection at the Naval Postgraduate School Flash X-ray facility". Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA237681.
Pełny tekst źródłaThesis Advisor(s): Maruyama, X.K. Second Reader: Michael, S.N. "June 1990." Description based on title screen as viewed on March 24, 2010. DTIC Descriptor(s): Data Acquisition, Electronics, Facilities, Instrumentation, Integrated Systems, Noise (Electrical And Electromagnetic), Photons, Pulse Generators, Pulses, Radiation, Requirements, Scale, Transient Radiation Effects, Transients, Trees, Wafers, X Rays. DTIC Identifier(s): Transient radiation effects, Data acquisition, X ray apparatus, Electromagnetic pulses, Theses. Author(s) subject terms: EMP, IEMP, Flash X-Ray Instrumentation. Includes bibliographical references (p. 105-106). Also available in print.
Manohar, Nivedh Harshan. "Effect of source x-ray energy spectra on the detection of fluorescence photons from gold nanoparticles". Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45970.
Pełny tekst źródłaHabib, Amr. "Détecteurs radiologiques grande surface, multi-énergie". Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENT055.
Pełny tekst źródłaThe objective of the thesis is to propose a solution for a 2D integrated circuit X-ray imager working, either in spectrometric mode where each X photon energy is measured, or in charge integration mode where the total energy deposited by X-ray during an image is measured, the solution being compatible with large area detectors typically of 20 cm x 20 cm. A proof of concept prototype ASIC 'Sphinx' was designed and fabricated in CMOS 0.13 µm technology; the ASIC being formed of a matrix of 20 x 20 pixels with a 200 µm pixel pitch. The designed architecture allows the quantification of the incoming charge through the use of counter-charge packets as low as 100 electrons. The injected packets are counted for each X photon (in the spectrometric photon counting mode), or for all charges integrated during the image period (in charge integration mode). First characterization measurements prove the validity of the concept with good performance in terms of power consumption, noise, and linearity. A first part of the ASIC is dedicated to X-ray direct detection where a semiconductor, e.g. CdZnTe, hybridized to the ASIC's pixels converts X-photons to electrical charge. Another part of the ASIC is dedicated indirect X-ray detection where a scintillator, e.g. CsI:Tl, is used to convert X-photons to visible photons which are then detected by in-pixel photodiodes. For the latter mode, new forms of photodiodes characterized by fast detection and low capacity were designed, simulated, and fabricated in CMOS 0.13 µm technology on a different ASIC. Finally, the thesis concludes with proposing performance enhancing ideas to be potentially implemented in a future prototype
Jackson, Gavin John. "Local adsorption structure determination of chemically-specific species using normal incidence X-ray standing wavefields". Thesis, University of Warwick, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343835.
Pełny tekst źródłaMiteva, Tsveta [Verfasser], i Lorenz S. [Akademischer Betreuer] Cederbaum. "Electronic decay cascades in media initiated by resonant absorption of X-Ray photons / Tsveta Miteva ; Betreuer: Lorenz S. Cederbaum". Heidelberg : Universitätsbibliothek Heidelberg, 2015. http://d-nb.info/1180500989/34.
Pełny tekst źródłaDawiec, Arkadiusz. "Développement d'une camera x couleur ultra-rapide a pixels hybrides". Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX22029/document.
Pełny tekst źródłaThe aim of the project, of which the work described in this thesis is part, was to design a high-speed X-ray camera using hybrid pixels applied to biomedical imaging and for material science. As a matter of fact the hybrid pixel technology meets the requirements of these two research fields, particularly by providing energy selection and low dose imaging capabilities. In this thesis, high frame rate X-ray imaging based on the XPAD3-S photons counting chip is presented. Within a collaboration between CPPM, ESRF and SOLEIL, three XPAD3 cameras were built. Two of them are being operated at the beamline of the ESRF and SOLEIL synchrotron facilities and the third one is embedded in the PIXSCAN II irradiation setup of CPPM. The XPAD3 camera is a large surface X-ray detector composed of eight detection modules of seven XPAD3-S chips each with a high-speed data acquisition system. The readout architecture of the camera is based on the PCI Express interface and on programmable FPGA chips. The camera achieves a readout speed of 240 images/s, with maximum number of images limited by the RAM memory of the acquisition PC. The performance of the device was characterize by carrying out several high speed imaging experiments using the PIXSCAN II irradiation setup described in the last chapter of this thesis
Liu, Min. "Radiation-induced processes within DNA in the gas phase". Electronic Thesis or Diss., Normandie, 2023. http://www.theses.fr/2023NORMC292.
Pełny tekst źródłaDNA damage is generally considered to be the most common and most important type of lesions in cells caused by ionizing radiation. While DNA damage caused by ionizing radiation poses serious risks to human health, it also makes radiation therapy a powerful tool for killing cancer cells and saving lives. For these reasons, a great deal of research has focused on radiation-induced processes within DNA. However, most of this work has been carried out in the condensed phase, which cannot remove the influence of the surrounding environment. In order to investigate the consequences of direct interaction of DNA with ionizing radiation at the molecular scale, we have irradiated a self-complementary DNA sequence in the gas phase with synchrotron radiation or ion beams, and analyzed the resulting product ions by mass spectrometry. Thanks to ion mobility spectrometry, we have established that deprotonated double strands of this sequence indeed form a double helix that is stable in an ion trap, if the charge state is higher than 5-. Then, we have investigated the consequences of specific photoabsorption occurring at the DNA oligonucleotide backbone in the gas phase. By monitoring non-dissociative single electron detachment from deprotonated precursors as a function of photon energy around the phosphorus K-edge, we have identified the X-ray spectral signature of selective photoabsorption at the phosphorus atoms located only in the backbone. We also detected abundant nucleobase fragment cations resulting from multiple electron detachment and thus demonstrated the charge, energy and hydrogen transfer from the backbone to the nucleobases. In the final part of the thesis, we present the results of irradiation of the DNA oligonucleotides by carbon ions in the gas phase. We have observed similar non-dissociative single electron detachment and similarly abundant positive fragment ions after carbon ion impact as in the case of irradiation by X-ray photons. More importantly, we have successfully irradiated a helical DNA double strand in the gas phase for the first time. 70% of the resulting ionic products come from non-dissociative single electron detachment, which is much higher than the case of single strands. Therefore, direct ionization of a DNA double helix after interaction with a single carbon ion does not lead to separation of the strands, which has important implications regarding DNA damage, notably in the context of hadrontherapy
Deloule, Sybelle. "Développement d'une méthode de caractérisation spectrale des faisceaux de photons d'énergies inférieures à 150 keV utilisés en dosimétrie". Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112273/document.
Pełny tekst źródłaIn the field of dosimetry, the knowledge of the whole photon fluence spectrum is an essential parameter. In the low-to-medium energy range (i.e. E<150 keV), the LNHB possess 5 X-ray tubes and iodine-125 brachytherapy seeds, both emitting high fluence rates. The performance of calculation (either Monte Carlo codes or deterministic software) is flawed by increasing uncertainties on fundamental parameters at low energies, and modelling issues. Therefore, direct measurement using a high purity germanium is preferred, even though it requires a time-consuming set-up and mathematical methods to infer impinging spectrum from measured ones (such as stripping, model-fitting or Bayesian inference…). Concerning brachytherapy, the knowledge of the seed’s parameters has been improved. Moreover, various calculated X-ray tube fluence spectra have been compared to measured ones, after unfolding. The results of all these methods have then be assessed, as well as their impact on dosimetric parameters
Dupont, Mathieu. "Tomographie spectrale à comptage de photons : développement du prototype PIXSCAN et preuve de concept". Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4011/document.
Pełny tekst źródłaIn the field of preclinical X-ray tomography, spectral tomography is actively explorated. The aims of spectral tomography are the caracterisation of tissues and contrast agentstogether with the quantification of the latter and the enhancement of contrast between soft tissues. This is achived by the exploitation of spectral information (i.e. energy) and not only the detected quantities of photons X. The interest in spectral tomography is enforced by the arrival of hybrid pixel cameras like XPAD, because of their ability to select photons according to their energy. The XPAD3 camera, third version of XPAD, is built to be used in the micro-CT demonstrator PIXCAN fully developped at CPPM.In this context, this thesis has two goals : a contribution to the developement of the PIXSCAN and a realisation of a proof of concept of spectral tomography in PIXSCAN. The first goal is done by developing the data acquisition system of PIXSCAN. To accomplish the second one, we perform spectral tomography by implementing component separation in order to isolate photoelectric, compton and contrast agents contribution. This work begins by the caracterisation of this method and ends by a proof of concept on real data acquired by PIXSCAN
Zhang, Zhipeng, Wenckstern Holger von, Jörg Lenzner i Marius Grundmann. "Wavelength-selective ultraviolet (Mg,Zn)O photodiodes: Tuning of parallel composition gradients with oxygen pressure". American Institute of Physics, 2016. https://ul.qucosa.de/id/qucosa%3A23555.
Pełny tekst źródłaBardho, Onelda. "Comprendre la physique des sursauts gamma grâce aux corrélations dans les données". Thesis, Nice, 2016. http://www.theses.fr/2016NICE4004/document.
Pełny tekst źródłaGRBs are ashes of gamma-rays coming from cosmos. They are one of the most mysteriousevents we have been able to observe since their discovery. GRBs are classified into two groups: long/soft GRBs and short/hard GRBs. Their emission mechanism consists of two phases: prompt emission and afterglow emission. The launch of the Swift satellite opened a New Era in the GRBs research. Swift is able to provide accurate position for more GRBs than previous missions, thanks to its fast capabilities of slewing. Furthermore, the Swift shows that GRBs have a canonical behaviour for the X-ray afterglow light curves. The data analysis process remains the key point of GRBs studies. I present a detailed study of the peculiar GRB 141221A at different wavelengths. GRB 141221A shows an unusual steep rise in the optical light curve of the afterglow. The broad band spectral energy distribution, taken near the maximum of the optical emission, presents either a thermal component or a behaviourbreak. This burst displays unusual feature in the optical band, whereas the X-ray data is more common. GRB 141221A is one of the challenging bursts that excludes a stellar wind from the progenitor of the GRBs. A clustering in the X-ray afterglow light curves was observed before the launch of the Swift satellite. This feature has been debated after the launch of the Swift. We have built a sample which consists of 254 GRBs that shows a scattering of the data for the flux distribution at one day. This distribution was investigated with a normalization of light curves at redshift one. We have investigated the problem into three different directions
Gibson, D. J. "A High-Energy, Ultrashort-Pulse X-Ray System for the Dynamic Study of Heavy, Dense Materials". Washington, D.C : Oak Ridge, Tenn. : United States. Dept. of Energy ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2004. http://www.osti.gov/servlets/purl/15011626-GeBNVt/native/.
Pełny tekst źródłaPublished through the Information Bridge: DOE Scientific and Technical Information. "UCRL-TH-207378" Gibson, D J. 09/17/2004. Report is also available in paper and microfiche from NTIS.
Chaleil, Annaïg. "Développement d’une source de rayonnement X par diffusion Compton inverse sur l'accélérateur ELSA et optimisation à l'aide d'un système d'empilement de Photons". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS398/document.
Pełny tekst źródłaX-ray sources based on inverse Compton scattering process produce tunable near-monochromatic and highly directive X-rays. Recent advances in laser and accelerator technologies make the development of such very compact hard X-ray sources possible. These sources are particularly attractive in several applications such as medical imaging, cancer therapy or culture-heritage study, currently performed in size-limited infrastructures. The main objective of this thesis is the development of an inverse Compton scattering source on the ELSA linac of CEA at Bruyères-le-Châtel as a calibration tool for ultra-fast detectors.A non-resonant cavity was designed to multiply the number of emitted X-ray photons. The laser optical path is folded to pile-up laser pulses at the interaction point, thus increasing the interaction probability. Another way of optimizing the X-ray yield consists in increasing the electron bunch density at the interaction point, which is strongly dependent on the electron energy. A facility up-grade was performed to increase the electron energy up to 30 MeV. The X-ray output gain obtained thanks to this system was measured and compared with calculated expectations and 3D PIC simulations
Pontes, Wesley. "Implementação de um sistema eletrônico para medir taxa de fluência de energia de radiação na faixa de radioterapia com sensor piroelétrico /". Ilha Solteira : [s.n.], 2011. http://hdl.handle.net/11449/103394.
Pełny tekst źródłaBanca: Cláudio Kitano
Banca: Walter Katsumi Sakamoto
Banca: Tony Inácio da Silva
Banca: Giuliano Pierre Estevam
Resumo: Sensores piroelétricos podem ser utilizados para medir a taxa de fluência de energia (intensidade) da radiação X na faixa de diagnóstico médico e de ortovoltagem. Neste trabalho, foi implementado um sistema eletrônico que pode medir taxa de fluência de energia de radiação gama de 1,25 MeV e fótons X de 6 MV e 15 MV. O sistema é constituído por um sensor piroelétrico, um conversor corrente-tensão de alta sensibilidade e um instrumento para registrar a forma de onda e medir o pulso do sinal produzido pelo sensor. Este instrumento pode ser um osciloscópio, um circuito microcontrolado associado a um display de cristal líquido, ou um módulo de aquisição de dados e um laptop. O sensor piroelétrico e o conversor corrente-tensão foram alojados em uma câmara piroelétrica blindada. Seis tipos de sensores piroelétricos foram avaliados, sendo três cerâmicas e três compósitos. Os resultados obtidos com o sistema eletrônico, utilizando os diferentes tipos de sensores, possibilitaram caracterizá-lo em termos de precisão, resolução e sensibilidade. O sistema apresentou resposta linear com a taxa de fluência de energia da radiação, precisão melhor que 3 % e resolução de 5,56 nW/m2. As constantes piezoelétricas d33 dos sensores utilizados não sofreram alteração após os mesmos terem sido irradiados com 45 Gy de radiação na faixa de radioterapia. Estas características, associadas à importância de se medir a taxa de fluência de energia de radiação ionizante, podem tornar o instrumento piroelétrico muito útil no monitoramento de radiação produzida por equipamentos de radioterapia
Abstract: Pyroelectric sensors have been be used to measure the energy fluence rate (intensity) of x-radiation in the range of medical diagnosis and orthovoltage. In this work, we implemented an electronic system that can measure the energy fluence rate of 1.25 MeV gamma radiation, 6 MV and 15 MV X-photons. The system consists of a pyroelectric sensor, a high sensitivity current-to-voltage converter and an instrument for measuring and recording the waveform of pulses produced by the pyroelectric sensor. This instrument may be an oscilloscope, a microcontrolled circuit associated with a liquid crystal display, or a data acquisition module connected to a laptop. The pyroelectric sensor and the current-tovoltage converter were placed in an shielded pyroelectric camera. Six types of pyroelectric sensors were evaluated, three ceramics and three composites. The results obtained with the electronic system, using different types of sensors, allowed us to characterize it in terms of precision, resolution and sensitivity. The system has linear response to the energy fluence rate of radiation, precision better than 3 % and resolution of 5,6 nW/m2. The piezoelectric constant d33 of the sensors used have not changed after these have been irradiated with 45 Gy of radiotherapy radiation. These characteristics, associated with the importance of measuring the ionizing radiation energy fluence rate may make the pyroelectric instrument very useful in monitoring radiation produced by radiotherapy equipments
Doutor
Amari, Smaïl. "Etude des matériaux pérovskites pour la détection directe des rayonnements ionisants". Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALI039.
Pełny tekst źródłaThe hybrid organic-inorganic perovskite MAPbBr3 is a promising semiconductor for X-ray detection applications. Photodetection in the energy range used in medical radiography requires a high material thickness (> 500 µm). The main objective of this work was to study the impact of solution growth conditions of millimeter thick crystals on crystal defects (strains, dislocations, inclusions, and impurities). In this context, we set up an original methodology for the rapid optimization of growth conditions based on growth mechanisms and growth kinetics monitoring. The growth conditions used enabled us to produce crystals covering a wide range of crystal defects. The impact of these defects on the electronic properties of MAPbBr3 single crystal X-ray detector devices was studied. It appears that strains, dislocations, impurities, and nanoscopic solvent inclusions have little impact on the resistivity and sensitivity of the detectors. On the other hand, a high density of micrometric inclusions tends to significantly degrade the electronic properties of the devices
Pontes, Wesley [UNESP]. "Implementação de um sistema eletrônico para medir taxa de fluência de energia de radiação na faixa de radioterapia com sensor piroelétrico". Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/103394.
Pełny tekst źródłaCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Sensores piroelétricos podem ser utilizados para medir a taxa de fluência de energia (intensidade) da radiação X na faixa de diagnóstico médico e de ortovoltagem. Neste trabalho, foi implementado um sistema eletrônico que pode medir taxa de fluência de energia de radiação gama de 1,25 MeV e fótons X de 6 MV e 15 MV. O sistema é constituído por um sensor piroelétrico, um conversor corrente-tensão de alta sensibilidade e um instrumento para registrar a forma de onda e medir o pulso do sinal produzido pelo sensor. Este instrumento pode ser um osciloscópio, um circuito microcontrolado associado a um display de cristal líquido, ou um módulo de aquisição de dados e um laptop. O sensor piroelétrico e o conversor corrente-tensão foram alojados em uma câmara piroelétrica blindada. Seis tipos de sensores piroelétricos foram avaliados, sendo três cerâmicas e três compósitos. Os resultados obtidos com o sistema eletrônico, utilizando os diferentes tipos de sensores, possibilitaram caracterizá-lo em termos de precisão, resolução e sensibilidade. O sistema apresentou resposta linear com a taxa de fluência de energia da radiação, precisão melhor que 3 % e resolução de 5,56 nW/m2. As constantes piezoelétricas d33 dos sensores utilizados não sofreram alteração após os mesmos terem sido irradiados com 45 Gy de radiação na faixa de radioterapia. Estas características, associadas à importância de se medir a taxa de fluência de energia de radiação ionizante, podem tornar o instrumento piroelétrico muito útil no monitoramento de radiação produzida por equipamentos de radioterapia
Pyroelectric sensors have been be used to measure the energy fluence rate (intensity) of x-radiation in the range of medical diagnosis and orthovoltage. In this work, we implemented an electronic system that can measure the energy fluence rate of 1.25 MeV gamma radiation, 6 MV and 15 MV X-photons. The system consists of a pyroelectric sensor, a high sensitivity current-to-voltage converter and an instrument for measuring and recording the waveform of pulses produced by the pyroelectric sensor. This instrument may be an oscilloscope, a microcontrolled circuit associated with a liquid crystal display, or a data acquisition module connected to a laptop. The pyroelectric sensor and the current-tovoltage converter were placed in an shielded pyroelectric camera. Six types of pyroelectric sensors were evaluated, three ceramics and three composites. The results obtained with the electronic system, using different types of sensors, allowed us to characterize it in terms of precision, resolution and sensitivity. The system has linear response to the energy fluence rate of radiation, precision better than 3 % and resolution of 5,6 nW/m2. The piezoelectric constant d33 of the sensors used have not changed after these have been irradiated with 45 Gy of radiotherapy radiation. These characteristics, associated with the importance of measuring the ionizing radiation energy fluence rate may make the pyroelectric instrument very useful in monitoring radiation produced by radiotherapy equipments
De, cesare Cinzia. "Traitements numériques pour l’amélioration de la stabilité des détecteurs spectrométriques à fort flux pour l'imagerie X". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT084/document.
Pełny tekst źródłaThe emergence of CdTe Photon Counting Detectors (PCD) with energy discrimination capabilities, opens up new perspectives in X-ray imaging. Medical and security applications are characterized by very high X-ray fluxes and consequently require a very fast shaper in order to limit dead time losses due to pile-up. However, if the shaper is faster than the collection of the charges in the semiconductor, there is a loss of charge called ballistic deficit. Moreover, variations of the electric field profile in the detector over time cause a change in the collection time of the charges. As a result, the conversion gain of the detector will be affected by these variations. The instability of the response is visible over time as a channel shift of the spectra, resulting in a false information of the photon energy. The aim of this work is to characterize this instability in order to understand the mechanisms behind them and to develop a method to correct its effect. We proposed a correction algorithm based on the use of two Single Delay Line (SDL) shaping amplifiers. A fast SDL is used to measure the X-ray spectra at high count rates with limited count rate losses. A slow SDL is used to measure the full collected charge in order estimate a correction factor for the compensation of the ballistic deficit fluctuations of the fast SDL. An important step is to sort the processed pulses in order to reject pile-up and other undesirable effects that may degrade the measurement of the correction factor. The proposed method was implemented in an FPGA in order to correct the ballistic deficit in real-time and to give a stable response of the detector at very high fluxes. The method was tested with a 4x4 pixels detector (CdTe) of 3 mm thickness and 800 micron pitch, which is able to measure transmitted X-ray spectra in the energy range of 20-160 kV on 256 energy bins. The developed method was initially tested at low count rate with a Co-57 and an Am-241 gamma-ray sources, then at high count rates up to ~2 Mc/s with an X-ray source. With the characterization and the validation of this innovative algorithm we prove its ability in providing a stable response of the detector over time without affecting the energy resolution (~7% at 122 keV) and the dead time (~70 ns)
Norlin, Börje. "Photon Counting X-ray Detector Systems". Licentiate thesis, Mid Sweden University, Department of Information Technology and Media, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-41.
Pełny tekst źródłaThis licentiate thesis concerns the development and characterisation of X-ray imaging detector systems. “Colour” X-ray imaging opens up new perspectives within the fields of medical X-ray diagnosis and also in industrial X-ray quality control. The difference in absorption for different “colours” can be used to discern materials in the object. For instance, this information might be used to identify diseases such as brittle-bone disease. The “colour” of the X-rays can be identified if the detector system can process each X-ray photon individually. Such a detector system is called a “single photon processing” system or, less precise, a “photon counting system”.
With modern technology it is possible to construct photon counting detector systems that can resolve details to a level of approximately 50 µm. However with such small pixels a problem will occur. In a semiconductor detector each absorbed X-ray photon creates a cloud of charge which contributes to the picture achieved. For high photon energies the size of the charge cloud is comparable to 50 µm and might be distributed between several pixels in the picture. Charge sharing is a key problem since, not only is the resolution degenerated, but it also destroys the “colour” information in the picture.
The problem involving charge sharing which limits “colour” X-ray imaging is discussed in this thesis. Image quality, detector effectiveness and “colour correctness” are studied on pixellated detectors from the MEDIPIX collaboration. Characterisation measurements and simulations are compared to be able to understand the physical processes that take place in the detector. Simulations can show pointers for the future development of photon counting X-ray systems. Charge sharing can be suppressed by introducing 3D-detector structures or by developing readout systems which can correct the crosstalk between pixels.
Wandersman, Elie. "Transition vitreuse de nanoparticules magnétiques en interaction". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2007. http://tel.archives-ouvertes.fr/tel-00193960.
Pełny tekst źródłaNiu, Pei. "Multi-energy image reconstruction in spectral photon-counting CT". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI022.
Pełny tekst źródłaSpectral photon-counting CT (sCT) appeared recently as a new imaging technique presenting fundamental advantages with respect to conventional CT and duel-energy CT. However, due to the reduced number of photons in each energy bin of sCT and various artifacts, image reconstruction becomes particularly difficult. This thesis focuses on the reconstruction of multi-energy images in sCT. First, we propose to consider the ability of sCT to achieve simultaneously both anatomical (aCT) and functional imaging (fCT) in one single acquisition through reconstruction and material decomposition. aCT function of sCT is studied under the same configuration as that of conventional CT, and fCT function of sCT is investigated by applying material decomposition algorithms to the same acquired multi-energy data. Then, since noise is a particularly acute problem due to the largely reduced number of photons in each energy bin of sCT, we introduce denoising mechanism in the image reconstruction to perform simultaneous reconstruction and denoising. Finally, to improve image reconstruction, we propose to reconstruct the image at a given energy bin by exploiting information in all other energy bins. The key strategy in such approach consists of grouping the similar pixels from the reconstruction of all the energy bins into the same class, fitting within each class, mapping the fitting results into each energy bin, and denoising with the mapped information. It is used both as a post-denoising operation to demonstrate its effectiveness and as a regularization term or a combined regularization term for simultaneous reconstruction and denoising. All the above methods are evaluated on both simulation and real data from a pre-clinical sCT system
Xie, Bingqing. "Image-domain material decomposition in spectral photon-counting CT for medical applications". Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI021.
Pełny tekst źródłaMaterial decomposition is a fundamental and primordial problem in spectral photon-counting X-ray CT (sCT). The present thesis focuses on the development of material decomposition methods using spectral and morphological information embedded in multi-energy sCT images. In this framework, three methods were developed. For the first method, by using bounded mass density, local joint sparsity and structural low-rank (DSR) in image domain, we achieve highly accurate decomposition of materials such as gadolinium, iodine and iron. The results on both numerical phantom and physical data demonstrated that the proposed DSR method leads to more accurate decomposition than usual pseudo-inverse method with singular value decomposition (SVD) and current popular sparse regularization method with L1-norm constraint. The second method works in a region-wise manner. It consists in optimizing basis materials based on spatio-energy segmentation of regions-of-interests (ROIs) in sCT images, reducing noise by averaging multi-energy spatial images, and performing a fine material decomposition involving optimized decomposition matrix, denoising regularization and sparsity regularization. The results on both digital and physical data showed that the proposed ROI-wise material decomposition method presents clearly higher reliability and accuracy compared to common decomposition methods based on total variation (TV) or L1-norm (lasso) regularization. In the third method, we propose the notion of super-energy-resolution (SER) sCT imaging, which is realized through establishing the relationship between simulation and physical phantoms by means of coupled dictionary learning in a pixel-wise way. The effectiveness of the proposed methods was validated on digital phantom, physical phantoms and in vivo data. The results showed that for the same decomposition method using lasso regularization, the proposed super-energy-resolution imaging presents much higher decomposition accuracy and detection ability compared to what can be provided by current sCT machine
Carr, James. "Error analysis of X-ray photon correlation spectroscopy measurements". Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117183.
Pełny tekst źródłaL'utilisation d'une théorie pour extraire des paramètres depuis des données expérimentales nécessite une compréhension des variations statistiques. De plus, l'amélioration d'une technique expérimentale repose sur la compréhension des sources d'erreurs and d'un modèle précis de l'effet des paramètres expérimentaux sur le signal et le bruit. La fonction de corrélation intensité-intensité de deuxième ordre est une quantité de mesure standardisée pour les expériences de diffusion de lumière dynamique et de spectroscopie de corrélation de photons en rayons X (X-ray Photon Correlation Spectroscopy, XPCS). Dans cette thèse, nous comparons les variances mesurées de la fonction de corrélation à un modèle basé sur les statistiques de diffusion de lumière dynamique. Nous démontrons l'accord entre le modèle de diffusion de lumière dynamique et les données XPCS. Les expériences XPCS sont en général effectuées avec un faible flux de photons et sont utilisées pourétudier les constantes à long terme. Pour atteindre des statistiques susantes, de détecteurs à résolution spatiale sont utilisés. Nous montrons l'existence de corrélations entre pixels voisins. Ces corrélations révèlent d'importantes caractéristiques qui doivent tre inclues afin de tirer des conclusions précises des expériences XPCS.
Watt, John. "A photon counting pixel detector for X-ray imaging". Thesis, University of Glasgow, 2001. http://theses.gla.ac.uk/1009/.
Pełny tekst źródłaSmith, David Alan. "A study of photon counters for X-ray astronomy". Thesis, University of Leicester, 1996. http://hdl.handle.net/2381/35791.
Pełny tekst źródłaNorlin, Börje. "Characterisation and application of photon counting X-ray detector systems". Doctoral thesis, Mittuniversitetet, Institutionen för informationsteknologi och medier, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-38.
Pełny tekst źródłaDenna avhandling berör utveckling och karaktärisering av fotonräknande röntgensystem. ”Färgröntgen” öppnar nya perspektiv för medicinsk röntgendiagnostik och även för materialröntgen inom industrin. Skillnaden i absorption av olika ”färger” kan användas för att särskilja olika material i ett objekt. Färginformationen kan till exempel användas i sjukvården för att identifiera benskörhet. Färgen på röntgenfotonen kan identifieras om detektorsystemet kan detektera varje foton individuellt. Sådana detektorsystem kallas ”fotonräknande” system. Med modern teknik är det möjligt att konstruera fotonräknande detektorsystem som kan urskilja detaljer ner till en upplösning på circa 50 µm. Med så små pixlar kommer ett problem att uppstå. I en halvledardetektor ger varje absorberad foton upphov till ett laddningsmoln som bidrar till den erhållna bilden. För höga fotonenergier är storleken på laddningsmolnet jämförbar med 50 µm och molnet kan därför fördelas över flera pixlar i bilden. Laddningsdelning är ett centralt problem delvis på grund av att bildens upplösning försämras, men framför allt för att färginformationen i bilden förstörs. Denna avhandling presenterar karaktärisering och simulering för att ge en mer detaljerad förståelse för fysikaliska processer som bidrar till laddningsdelning i detektorer från MEDIPIX-projekter. Designstrategier för summering av laddning genom kommunikation från pixel till pixel föreslås. Laddningsdelning kan också begränsas genom att introducera detektorkonstruktioner i 3D-struktur. I nästa generation av MEDIPIX-systemet, Medipix3, kommer summering av laddning att vara implementerat. Detta system, utrustat med en 3D-detektor i kisel, eller en tunn plan detektor av högabsorberande material med god kvalitet, har potentialen att kunna kommersialiseras för medicinska röntgensystem. Detta skulle bidra till bättre folkhälsa inom hela Europeiska Unionen.
Norlin, Börje. "Characterisation and application of photon counting X-ray detector systems /". Sundsvall : Mittuniversitetet, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-38.
Pełny tekst źródłaFredenberg, Erik. "Spectral Mammography with X-Ray Optics and a Photon-Counting Detector". Doctoral thesis, KTH, Medicinsk avbildning, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11641.
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Stana, Markus, Michael Leitner, Manuel Ross i Bogdan Sepiol. "Studies of atomic scale diffusion by X-ray photon correlation spectroscopy". Diffusion fundamentals 20 (2013) 102, S. 1-2, 2013. https://ul.qucosa.de/id/qucosa%3A13691.
Pełny tekst źródłaStana, Markus, Michael Leitner, Manuel Ross i Bogdan Sepiol. "Studies of atomic scale diffusion by X-ray photon correlation spectroscopy". Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-183943.
Pełny tekst źródłaFennell, Sharon M. "A novel x-ray tube for the non destructive examination of light materials". Thesis, University of Warwick, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300713.
Pełny tekst źródłaTurner, Joseph B. McGee. "Determination and analysis of multi photon excitation e missive species". Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/5822.
Pełny tekst źródłaThe entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (May 23, 2006) Vita. Includes bibliographical references.
Fabris, Nicola. "Instrumentation for Photon Handling of XUV and Soft X-ray Ultrafast Pulses". Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3425791.
Pełny tekst źródłaDamrongkijudom, Nyanpen. "Analysis of lepton contamination in high energy x-ray beams". Access electronically, 2007. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20080121.120415/index.html.
Pełny tekst źródłaPivot, Odran. "Scatter correction for spectral computed tomography". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI102.
Pełny tekst źródłaScattered radiation is a major cause of bias, loss of contrast and artifacts in x-ray computed tomography (CT). Many correction methods have been proposed for conventional CT (using energy-integrating detectors) but it is still an open research topic in the field of spectral CT, a novel imaging technique based on the use of energy-selective photon counting detectors. The main objective of the present thesis was to investigate scatter correction techniques adapted to spectral CT. The chosen solution refines a scatter correction method developed for integration-mode CT which uses a semi-transparent primary modulator mask. The attenuation of the primary modulator mask is first compensated for with a correction matrix which takes advantage of the spectral information. The other contributions are a scatter model based on B-splines allowing an accurate representation of scatter maps with the aid of a very few parameters and a cost function which takes into account the structures of the mask and the object. The accuracy of the correction matrix, the scatter model and the whole proposed scatter correction process were tested on simulated data considering photon counting detectors with various numbers of energy bins and have shown a significant bias reduction, contrast enhancement and artifact removal. In addition, physical experiments were performed using a parallel fan-beam set-up with a commercial energy-resolved detector. The method was successfully validated in the case of two phantoms dedicated to medical image quality measurements, with a remarkable improvement
Doesburg, Robert Michael Nicolas. "The MARS Photon Processing Cameras for Spectral CT". Thesis, University of Canterbury. Physics and Astronomy, 2012. http://hdl.handle.net/10092/7327.
Pełny tekst źródłaEdling, Fredrik. "DIXI – a Hybrid Pixel Detector for X-ray Imaging". Doctoral thesis, Uppsala University, Department of Nuclear and Particle Physics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4572.
Pełny tekst źródłaMedical X-ray imaging is an important tool in diagnostic radiology. The ionising-radiation dose to the patient is justified by the clinical benefit of the examination. Nonetheless, detectors that operate at even lower doses and provide more information to the radiologist are desired. A hybrid pixel detector has the potential to provide a leap in detector technology as it incorporates a more advanced signal-processing capability than currently used detectors.
The DIXI digital detector is a hybrid pixel detector developed for X-ray imaging. It consists of a readout chip and a semiconductor sensor. The division in two parts makes it possible to optimise each part individually. The detector is divided into square pixels with a size of 270 x 270 μm2. DIXI has the ability to count single photons and every readout pixel has two embedded counters to allow the acquisition of two images close in time. A discriminator enables the selection of photons with energies above a preset threshold level.
The readout chip Angie has been developed and its performance has been evaluated in terms of noise, threshold variation and capability to perform energy weighted counting. Silicon sensors have been fabricated, and a control system for DIXI has been designed and built. An electroless process for deposition of Ni/Au bumps on the chip and sensor has been optimised as a preparation for the assembly of a complete detector, which is being assembled by flip-chip bonding using anisotropic conductive film.
A simulation library for the DIXI detector has been set up and results on the image quality are reported for different exposures and working conditions. A theoretical model for hybrid pixel detectors based on the cascaded linear system theory has been developed. The model can be used to investigate and optimise the detector for different detector configurations and operating conditions.
Schürmann, Christian Joseph. "Chemical Concepts and X-ray Technologies challenged by Charge Density". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://hdl.handle.net/11858/00-1735-0000-002E-E5EC-B.
Pełny tekst źródłaYeo, Inhwan. "New methods for improving x-ray film in-phantom dosimetry for megavoltage photon radiotherapy". Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/17615.
Pełny tekst źródłaYilmaz, Ercan. "Characteristic X-ray, Photoelectron And Compton-scattered Photon Escape From A Hpge Detector". Phd thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/3/1210061/index.pdf.
Pełny tekst źródłaHuang, Zheng. "Dynamic Heterogeneity Analysis of Silica Reinforced SBR Using X-ray Photon Correlation Spectroscopy". University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron161978180718311.
Pełny tekst źródłaEriksson, Charlotte. "Optimization of Dual Energy data acquisition using CdTe-detectors with electronic spectrum splitting". Thesis, Linköpings universitet, Tekniska högskolan, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-94742.
Pełny tekst źródłaSarker, Suchismita. "Atom Dynamics of Amorphous Materials by X-Ray Photon Correlation Spectroscopy (XPCS) & Neutron Spectroscopy". Thesis, University of Nevada, Reno, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10619898.
Pełny tekst źródłaThe mitigation of greenhouse gas emissions on the environment led to the development of non-polluting hydrogen fuel cell use in automobiles. Syngas produced from coal gasification is converted to H2 and CO2 gasses by the water shift reaction. Metallic membranes are used to separate H 2 from CO2 and other gasses obtained from the water shift reaction of coal-derived syngas. Commercial crystalline Pd-Ag membranes are widely used for this purpose; however, Pd is an expensive strategic metal. Thus, inexpensive Ni-Nb-Zr alloys are studied.The permeation property of amorphous membranes are known, however, the mechanism of permeation and the nature of the local atomic order of the amorphous membranes was not fully understood.
In this study, atom dynamics studied by synchrotron x-ray photon correlation spectroscopy (XPCS) showed the movement of heavier elements such as Ni, Nb, and Zr, at room temperature and 373K. The addition of hydrogen significantly accentuates the motion of atoms as the hydrogen occupies the tetrahedral sites within the icosahedra leading to expansion and short-range diffusion, and no long-range diffusion is observed estimated to be ∼10-22 m2/s. Vacuum removal of hydrogen from these membranes showed a contraction of the icosahedra and approached to its original position. This suggests that the process reversible due to the pressure gradient. The XPCS results did not reveal the specific position of hydrogen atoms in the icosahedra; hydrogen goes into the tetrahedral sites of Zr4 and distorted Nb4 sites as determined by neutron vibrational spectroscopy. Total neutron scattering and DFT-MD simulation determine the short-range order of up to 1.8 nm and the nearest neighbor bond distances. Determination of cluster formation was first attempted by using small neutron scattering, but it did not have appropriate “Q” range. Thus atom probe tomography (APT) was attempted. This APT study revealed Nb-rich and Zr-rich clusters embedded in Ni-rich matrix, whose compositions are reported. DFT-MD simulation reveals interconnected icosahedra in the metal matrix. The atom dynamics (NVS and XPCS), atom probe tomography, total neutron scattering studies are discussed which have implication in the mechanisms of hydrogen permeation in amorphous metallic membranes.
Ksenia, Chechet. "Edge Illumination technique using direct conversion photon counting detectors for X-ray Phase Contrast imaging". Thesis, KTH, Fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-170408.
Pełny tekst źródłaPatel, Shamim. "Single photon counting X-ray diffraction techniques for the investigation of shock compressed condensed matter". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:864f1766-eb75-456e-a66d-950faa6c24ed.
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