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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 źródłaChaput, Julien. "Étude d'un détecteur CMOS hybride à semi-conducteur et comptage de photons : application à l'imagerie X". Clermont-Ferrand 1, 2005. http://www.theses.fr/2005CLF1MM11.
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
Poggioli, Luc. "Étude de la fonction de structure du photon Fγ₂(x, Q²) à l'aide du détecteur CELLO". Paris 11, 1988. http://www.theses.fr/1988PA112264.
Pełny tekst źródłaThibaudeau, Christian. "Tomodensitométrie par comptage de photons avec discrimination en énergie". Thèse, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/8337.
Pełny tekst źródłaMazal, Daniel Alejandro. "Radiothérapie stéréotaxique par petits faisceaux de rayons x de haute énergie : développement des moyens techniques et dosimétriques". Toulouse 3, 1990. http://www.theses.fr/1990TOU30069.
Pełny tekst źródłaGalarowicz, 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.
IKHLEF, ABDELAZIZ. "Imagerie x appliquee a l'etude d'un detecteur a fibres optiques scintillantes et d'une source de photons x a etincelle dans le vide". Paris 6, 1993. http://www.theses.fr/1993PA066574.
Pełny tekst źródłaDupont, 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
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
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 źródłaBachaalany, Mario. "Utilisation de capteurs CMOS rapides pour l'imagerie X à très haute sensibilité". Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00955895.
Pełny tekst źródłaZefkili, Sofia. "Qualité des faisceaux de photons de haute énergie issus des accélérateurs médicaux à distance de l'axe central". Toulouse 3, 1995. http://www.theses.fr/1995TOU30007.
Pełny tekst źródłaMosse, Caroline. "Spectroscopie X haute résolution à 1 et 2 photons : applications et perspectives pour les plasmas chauds et denses". Aix-Marseille 1, 1997. http://www.theses.fr/1997AIX11026.
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
Su, 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
Miteva, 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 źródłaLessard, François. "Validation d'un détecteur à fibre scintillante plastique pour la dosimétrie de photons aux énergies diagnostiques". Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/29448/29448.pdf.
Pełny tekst źródłaChaleil, 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
Amaro, Pedro. "Etude des transitions interdites dans les systèmes atomiques". Paris 6, 2011. http://www.theses.fr/2011PA066736.
Pełny tekst źródłaCuisset, Arnaud. "Dynamique vibrationnelle sondée par échos de photons de DCl et des complexes (DCl)x(N2)n piégés en matrice cryogénique". Paris 11, 2003. http://www.theses.fr/2003PA112323.
Pełny tekst źródłaVibrational dynamics in the ground electronic state of molecules trapped in cryogenic matrices is a relevant approach for the description of the specific interactions between a molecule and its surrounding. This vibrational dynamics was probed by photon echoes experiments using the Free Electron Laser of C. L. I. O (Centre Laser Infrarouge d'Orsay). Theses experiments make it possible on the one hand a direct measurement of the vibrational dephasing time T2, extremely sensitive to the interactions with the environment and on the other hand, a study of the spectral diffusion induced by vibrational energy transfer processes between the trapped molecules. We have chosen a simple system with a well-known spectroscopy: DC1 trapped in matrices. With this system, we are able to study within the same sample different species and to probe different interactions. In solid N2, photon echoes give a complete decription of monomer vibrational dynamics. The time-resolved signals obtained by excitation of dimers and trimers exhibit a clear influence of hydrogen bond on vibrational dynamics. In addition, experiments in argon matrix were realized probing mainly the (DC1)X-(N2)n complexes. The comparison with the results in solid nitrogen points out the strong difference between complexation effects and matrix effects on vibrational dynamics
Lalande, Mathieu. "Processus induits par l'irradiation de modèles peptidiques de la triple hélice du collagène en phase gazeuse". Thesis, Normandie, 2018. http://www.theses.fr/2018NORMC235/document.
Pełny tekst źródłaCollagen is the most abundant protein in mammals, and the main constituent of the extracellular matrix of cartilage. The mechanical properties of this tissue are due to the particular triple helical structure of collagen. In this thesis, we focused on peptidic models of the collagen triple helix in thegas phase, which allows reaching their intrinsic properties, including fundamental processes induced by ionizing radiations. An ion mobility spectrometry study of these systems proved that they retain their structural and stability properties in the absence of solvent. In addition, these stability properties also play a role after irradiation with ionizing photons in an ion trap. Furthermore, we have observed, thanks to mass spectrometry, a transition between photo-excitation and photoionization as the energy of the absorbed photon increases in the VUV-X range. Part of this energy is also redistributed in the vibration modes of the system, increases with photon energy, and induces intramolecular as well as intramolecular fragmentation of the triple helix. For the first time, we irradiated peptides in the gas phase by a carbon ion beam having a kinetic energy relevant in the context of hadrontherapy. A process that was absent from studies with photons has been observed : proton detachment. In the last chapter, the validation of a new experimental device dedicated to the irradiation of proteins and DNA strands in a cross-beam configuration, as well as the first results obtained, will be reported
Aouine, Mimoun. "Simulation Monte Carlo de l'émission X : Exploitation des spectres d'analyse d'interfaces obtenus au microscope électronique à transmission". Lyon, INSA, 1994. http://www.theses.fr/1994ISAL0128.
Pełny tekst źródłaThis work is related to the general framework of activities concerning electron microscopy. Especially, X-ray spectroscopy is a very powerful tool used by physicists and metallurgists. . . Its field of application is commonly the study of new materials; more complex, their development is conditioned to a detailed microstructural characterization. Our work brings a contribution to the methodology of analyzing X-spectra acquired in a transmission electron microscope. We have proposed a method in order to evaluate complex cases, which are frequently encountered during microscopic observations of real materials. Such cases define a same class of problems, i. E. That the very local chemical analysis near an interface(s), or, generally speaking, chemical segregations. We have approached the problem by means of simulation of the X-ray emission, coupled with a mathematical deconvolution method of spreading effects of the electron beam. A specific software has been developed on PC-type computers. The use of the Visual-Basic tool kit bas allowed a friendly user interface to be written. The next step of our work concerns three cases of analysis met in the laboratory: the distribution of the titanium specie near a Mullite / Zircon interface in a ceramics material - the evaluation of the copper concentration gradient after its implantation in alpha-alumina - the study of a corrosion process of alumina grains during creep of an alumina ceramic containing Mg, K and beta-alumina precipitates. Results obtained in all these cases, show the interest of our approach, and point out the advantages offered by our software, which might then be of a great help for microscopists
Dupont, M. "Tomographie spectrale à comptage de photons~: développement du prototype PIXSCAN et preuve de concept". Phd thesis, Aix-Marseille Université, 2014. http://tel.archives-ouvertes.fr/tel-01019735.
Pełny tekst źródłaGuo, Weiming. "Epitaxie hétérogene de GaP sur substrat Si (001) et nanostructures pour application photonique". Rennes, INSA, 2010. http://www.theses.fr/2010ISAR0036.
Pełny tekst źródłaThis thesis deals with the heterogeneous MBE growth of GaP thin layer on Si substrate to be used as a buffer layer, and the growth of optically active emission centre on GaP substrate. The ultimate goal is to realise an optical source on Si substrate, which can be used for optical interconnections in Opto-Electronic Integrated Circuit (OEIC). The first part deals with the growth optimisation of 20nm GaP buffer layer on Si. The influence of the Si surface preparation and the growth parameters (temperature, V/III flux ratio, antimony prelayer…) is studied. We demonstrate that Migration Enhanced Epitaxy (MEE) at low temperature allows a significant reduction of the surface roughness and a crystalline quality improvement. In the second part, we report the growth and structural study of 20 nm GaP/Si epilayers, using a fast, robust and non destructive analysis. This analysis, including atomic force microscopy and advanced X-ray diffraction, is applied to samples grown by different MBE growth modes. Roughness, lateral coherent length of epilayer, ratio of Anti-Phase Domains (APD) and their relation are discussed. The MEE growth at low temperature is found to guarantee a inetics-limited growth process which allows the annihilation of Anti-Phase Boundary (APB) within thin growth thickness. The annealing after MEE growth at 600°C is accompanied by an obvious increase of surface roughness and APD density. An APB-related atom redistribution model is proposed to explain this phenomenon. The third part focuses on the growth of active emission centre on GaP. The studied systems include: InAs, InP, GaAs Quantum Dot (QD), GaAsP, and GaAsPN Quantum Well (QW). For InAs/GaP system, the lack of photoluminescence (PL) at low temperature is attributed to plastic relaxation. The InP QD gives PL until 180K. Room temperature (RT) PL at 1. 8eV is observed for GaAs QD and GaAsP QW. Preliminary results on the growth of GaPAs(N)/GaPN quantum wells demonstrates Room Temperature PL and wavelength shift with small amount of nitrogen incorporated. RT electronluminescence of GaAsPN/GaPN/GaP diode and PL of GaAsPN/GaPN/GaP/Si structure until 200K suggests that such material system is promising for the realization of monolithically integrated photonic devices on Si
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 źródłaKronland-Martinet, Carine. "Développement de la tomographie intra-vitale au K-edge avec la camera à pixels hybrides XPAD3". Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4045.
Pełny tekst źródłaThe hybrid pixel camera XPAD3 integrated in the micro-CT PIXSCAN II is a new device for which photon counting replaces charge integration used in standard X-ray CT. This novel approach involves advantages, in particular the absence of dark noise and the ability to set an energy threshold on each pixel of the detected photons. This features has been exploited during this thesis work for standard small animal preclinical imaging and permitted to establish the faisability of ex vivo, and then in vivo labelling of marcrophages. On another hand, the ability of this camera is of uppermost importance for the development of K-edge imaging approaches, which exploit spectral information on the counted photons. K-edge imaging permits to identify contrast agent compartiments with regards to bones in classical radiography. K-edge imaging is obtained by selecting, for each pixel calibration, those pixel that are set at one of the three different thresholds around the K-shell’s binding energy of the selected contrast agents and then to proceed with a subtraction analysis to the images obtained above and below the K-edge energy. We develop a new way of calibrating the XPAD3 detector that permits to provide the proof of concept of a patent, and to obtain the first results on living mice by dividing the acquisition time by three with a compromise on the resolution. This novel approach can be implemented in “2 colours” in order to separate clearly two different contrast agents. This brings a new way to visualize biological information and to provide possible future approaches for the study of the inter-dependance of vascularisation and inflammation during the tumor development
Rault, Mathieu. "Elaboration et études des propriétés électriques de céramiques d'iodure de mercure pour la converison directe des photons X appliquée à l'imagerie dentaire". Paris 6, 2013. http://www.theses.fr/2013PA066809.
Pełny tekst źródłaZhang, 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 źródłaAbdelmouleh, Marwa. "Processus intrinsèques radio-induits dans des complexes non-covalents d'intérêt biologique et pharmaceutique". Thesis, Normandie, 2020. http://www.theses.fr/2020NORMC219.
Pełny tekst źródłaNon-covalent bonds play a crucial role in many processes involving molecular systems of biological and pharmaceutical interest, in particular in molecular recognition between a ligand and its receptor. However, their response upon ionizing radiation has scarcely been investigated for understanding radio induced processes. In the first part of this thesis, we present results of photo-absorption experiments of non-covalent complexes containing the vancomycin antibiotic, carried out by means of a mass spectrometer coupled to synchrotron beamlines producing photons in the X and VUV energy range. First, we show that the fragmentation of molecular systems after absorption of one VUV photon is partly correlated with the geometrical structure of the complex. In addition, the processes induced strongly depend on the charge state of the vancomycin/receptor complexes (protonated or deprotonated). For the protonated complex, the cleavage of non-covalent bonds is much more probable than for the deprotonated complex, in which the native interactions are conserved in the gas phase. Moreover, the absorption of one X-Ray photon by vancomycin leads to fragments that can be considered as a spectral signature of its post-translational modifications. This signature is robust not only in terms of photon energy but also of the molecular environment of vancomycin. The second part deals with the study of a protonated tri-peptid in the gas phase by mass and ion mobility spectrometry, and more particularly the effects of nano-solvation by the presence of one or more molecules of crown-ether. We are interested in the fragmentation induced by collision with a rare gas, or by electron transfer or capture, and we have shown that crown ether is not always spectator since it can lower the charge state of protonated peptides by abstracting a proton or a protonated molecule from it, and can even change binding site after electron transfer
Dawiec, Arkadiusz. "Développement d'une caméra à rayons X ultra-rapide utilisant des détecteurs à pixels hybrides". Phd thesis, Université de la Méditerranée - Aix-Marseille II, 2011. http://tel.archives-ouvertes.fr/tel-00631274.
Pełny tekst źródłaMordant, Maurice. "Résolution de l'équation du transport en géométrie X-Y ou R-Z à deux dimensions par des méthodes d'éléments finis sur l'espace des phases". Paris 11, 1985. http://www.theses.fr/1985PA112135.
Pełny tekst źródłaWe describe the measurement of the νμ, ν̅μ and (ν̅e) charged current interaction rates on iron in the CDHS detector at CERN for incident energies above 20 Gev. The neutrinos were produced by dumping a 400 Gev/c proton beam into copper targets of different density (“beam dump 1982”). Using an extrapolation to a target of infinite density, we determine these rates for direct neutrinos (neutrinos produced either directly of from short lived particle decays). The results are all significantly different from zero. The ratio of (νe + ν̅e) interaction rates is 0,88 +̠ 0,13 (stat. ) +̠ 0,05 (syst. ), in agreement with the electron-muon universality. However, these results are at variance with similar measurements at CERN by the CHARM collaboration. Interpreting the direct neutrinos as the product of charmed particle decays (D, D̅, ΛC), we determine some parametrizations fort their differential production cross sections. We find the total cross section for cc̅ production to be 35 +̠ 10 μb/nucleon. Finally, the observation of dimuon events yields limits for the product of the production X interaction cross sections for new particles
Firmino, Sandro Fernandes. "Transmissão e fluência de fótons na área de radiodiagnóstico para diferentes configurações de feixes e blindagens". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/25041.
Pełny tekst źródłaThis work presents a study of the influence of the compositions of shielding materials and variations in the spectra emitted by X-ray equipment by using a computer program that uses the Monte Carlo technique. The flux of photons was determined after the shielding material, with realistic geometries of the primary beam energy spectra used in the practice of diagnostic radiology, generating in this way, a database representative of the average transmission and fluence for the materials studied. With the proposed method, we seek to analyze the influence of barium composition of the mortar, and concrete transmission curves and their influence in determining the shielding thickness, and the influence of altering the characteristics of the radiation spectrum in the transmission of X photons. The methodology of this study was conducted in two stages: analysis with data streaming and transmission spectra with monoenergetic and polienergetics beams, keeping the same settings of the internal geometry of the simulation, for example, the total filtration, the ripple and the effective angle beam, although considering a shielding material for the monoenergetic spectrum and three materials for the polienergetic spectrum; the intercomparison between the same shielding material by changing the total filtration, ripple, and the angle of flight of the internal geometry simulation. As a result it was possible to analyze the simulated data, presenting among mean transmission data of photons, due to different compositions, but these differences are not significant enough to influence the thicknesses of shielding estimation used in the construction industry. This work also presents a database containing the fluence of X-irradiation, the shielding for the various beams and wall materials, and a database containing the curves and their equations to fit the curves of transmission for different materials studied. The evaluation of the change in transmission due to variations in the emission spectrum of X-rays showed great importance on the influence of these factors in the formation of the spectrum. Changes in the composition of the spectrum, due to variations in the total aluminum filtration, increased the power of penetration into the absorbing material and its average energy. Changes in the composition of the spectrum due to changes in the angle of the anode and the ripple, showed their influence in the estimation of transmission curves of X-photons, where the increase in the effective angle and ripple in the spectrum increases the participation of low energy photons, and decreases the average energy of the beam and half-value layer, and a differentiated participation in the formation of radiographies. Future work will be carried on simulations of many points of thicknesses and stories, allowing a better statistical analysis of simulated data, thus minimizing the relative errors. Moreover, it is suggested that this method be his applied to different materials and compositions of shielding materials in order to generate a database to assist in radiological protection in the field of general radiology.
Chantepie, B. "Étude et réalisation d'une électronique rapide à bas bruit pour un détecteur de rayons X à pixels hybrides destiné à l'imagerie du petit animal". Phd thesis, Université de la Méditerranée - Aix-Marseille II, 2008. http://tel.archives-ouvertes.fr/tel-00366861.
Pełny tekst źródłaAmari, 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
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.
Chantepie, Benoît. "Etude et réalisation d'une électronique rapide à bas bruit pour un détecteur de rayons X à pixels hybrides destiné à l'imagerie du petit animal". Aix-Marseille 2, 2008. http://theses.univ-amu.fr.lama.univ-amu.fr/2008AIX22114.pdf.
Pełny tekst źródłaSince the invention of computerized tomography (CT), charge integration detector were widely employed for X-ray biomedical imaging applications. Nevertheless, other options exist. A new technology of direct detection using semiconducors has been developped for high energy physics instrumentation. This new technology, called hybrid pixel detector, works in photon counting mode and allows for selecting the maximum energy of the counted photons. The iXgam research team at CPPM develops the PIXSCAN demonstrator, a CT-scanner using the hybrid pixel detector XPAD. The aim of his project is to evaluate the improvement on image quality and on dose delivered durinf X-ray examinations of a small animal. After a first prototype of hybrid pixel deector XPAD1 proving the feasibility of the project, a complete imager XPAD2 was designed and intergrated in the PIXSCAN demonstrator. Since then, with the evolution of microelectronic industry, important improvements are conceivable. To reducing the size of pixels and to improving the energy resolution of detectors, a third design XPAD3 was conceived and will be soon integrated in a second generation of PIXSCAN demonstrator. In this project, my thesis(s work consisted in taking part to the design of the detector readout electronics, to the characterization of the chips and of the hybrid pixel detectors, and also to the definition of a autozeroing architecture for pixels
Cabanac, Clément. "Variabilité temporelle des binaires-X : observations avec INTEGRAL ; modélisation". Phd thesis, Grenoble 1, 2007. http://www.theses.fr/2007GRE10043.
Pełny tekst źródłaThe exact origin of the observed X and Gamma ray variability in X-ray binaries is still an open debate in high energy astrophysics. Among others, these objects are showing aperiodic and quasiperiodic luminosity variations on timescales as small as the millisecond. This erratic behavior must put constraints on the proposed emission processes occuring in the vicinity of the neutron star or the stellar mass black-hole held by these objects. We propose here to study their behavior following 3 different ways: first we examine the evolution of a particular X-ray source discovered by INTEGRAL, IGR J19140+0951. Using timing and spectral data given by different instruments, we show that the source type is plausibly consistent with a High Mass X-ray Binary hosting a neutron star. Subsequently, we propose a new method dedicated to the study of timing data coming from coded mask aperture instruments. Using it on INTEGRAL/ISGRI real data, we detect the presence of periodic and quasi-periodic features in some pulsars and microquasars at energies as high as a hundred keV. Finally, we suggest a model designed to describe the low frequency variability of X-ray binaries in their hardest state. This model is based on thermal comptonization of soft photons by a warm corona in which a pressure wave is propagating in cylindrical geometry. By computing both numerical simulations and analytical solution, we show that this model should be suitable to describe some of the typical features observed in X-ray binaries power spectra in their hard state and their evolution such as aperiodic noise and low frequency quasi-periodic oscillations
Cabanac, Clément. "Variabilité temporelle des binaires-X : observations avec INTEGRAL ; modélisation". Phd thesis, Université Joseph Fourier (Grenoble), 2007. http://tel.archives-ouvertes.fr/tel-00161499.
Pełny tekst źródłaNous nous proposons dans ce manuscrit d´étudier le comportement de ces objets sous 3 angles différents : tout d´abord nous suivons l´évolution d´une source découverte par le satellite INTEGRAL, IGR J19140+0951. Par une étude spectro-temporelle et multi-instruments nous montrons que celle-ci doit vraisemblablement appartenir à la classe des binaires X de grande masse et abriter une étoile à neutron. Ensuite, nous proposons une nouvelle technique adaptée à l´étude temporelle des données provenant d´instruments à masques codés. Nous mettons en évidence par ce biais la présence de comportement périodiques et quasi-périodiques dans les données INTEGRAL/ISGRI de certains pulsars ou microquasars, jusqu'à des énergie proches de la centaine de keV.
Enfin, nous proposons un modèle pour décrire la variabilité à basse fréquence des états les plus durs des binaires-X. Celui-ci est basé sur la comptonisation thermique de photons mous par une couronne chaude soumise à une onde de pression en géométrie cylindrique. Nous montrons alors par des solutions analytiques et une résolution numérique du problème qu´un tel modèle pourrait permettre de décrire certaines composantes observées dans les spectres de puissance des états durs ainsi que leur évolution tels que le bruit apériodique et certaines oscillations périodiques de basses fréquences.
Niu, 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
Bardho, 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
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 źródłaFourcade, Paul. "Pompage séquentiel dans les lasers collisionnels x-uv. Etude d'un laser à fer neonoïde bi-impulsionnel a 25,5 nm en vue de la réalisation d'un double passage dans le milieu amplificateur. Application : photoionisation double dans le xénon, par absorption de photons lasers x-uv a 58 ev". Paris 13, 2001. http://www.theses.fr/2001PA132010.
Pełny tekst źródłaPontes, 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
Mazurier, Jocelyne. "Adaptation du code de monte carlo penelope pour la metrologie de la dose absorbee : caracterisation des faisceaux de photons x de haute energie et calcul de facteurs de correction de dosimetres de reference". Toulouse 3, 1999. http://www.theses.fr/1999TOU30183.
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