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Courteau, Pierre. "Electron arc therapy dose calculation using the angle-b concept." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=57004.
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A computer program was developed during the course of this work to calculate electron arc dose distributions with the angle $ beta$ concept. The angle $ beta$ uniquely describes the dependence of radial percentage depth doses an electron arc therapy on the nominal field width, isocenter depth, and virtual source-axis distance. The $ beta$ concept can be used in clinical situations to determine the field width when the isocenter depth and the required radial percentage depth dose are known. This thesis presents an overview of the physical properties of electron arc therapy and describes in detail the angle $ beta$ pseudo-arc technique used at McGill. A description of the algorithms used in the computer program is given the $ beta$ technique is compared to measurements and other calculation methods.
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Bernshteyn, Aleksandr 1975. "High speed electron-beam dose modulation by electrostatic quadra-deflection." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80053.
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Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (p. 47-49).
by Aleksandr Bernshteyn.
S.B.and M.Eng.
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Chan, Kin Wa (Karl), University of Western Sydney, of Science Technology and Environment College, and School of Computing and Information Technology. "Lateral electron disequilibrium in radiation therapy." THESIS_CSTE_CIT_Chan_K.xml, 2002. http://handle.uws.edu.au:8081/1959.7/538.
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The radiation dose in radiation therapy is mainly measured by ion chamber. The ion chamber measurement will not be accurate if there is not enough phantom material surrounding the ion chamber to provide the electron equilibrium condition. The lack of electron equilibrium will cause a reduction of dose. This may introduce problems in treatment planning. Because some planning algorithms cannot predict the reduction, they over estimate the dose in the region. Electron disequilibrium will happen when the radiation field size is too small or the density of irradiated material is too low to provide sufficient electrons going into the dose volume. The amount of tissue required to provide electron equilibrium in a 6MV photon beam by three methods: direct calculation from Klein-Nisina equation, measurement in low density material phantom and a Monte Carlo simulation is done to compare with the measurement, an indirect method from a planning algorithm which does not provide an accurate result under lateral electron disequilibrium. When the error starts to happen in such planning algorithm, we know that the electron equilibrium conditions does not exist. Only the 6MV photon beam is investigated. This is because in most cases, a 6MV small fields are used for head and neck (larynx cavity) and 6MV fields are commonly used for lung to minimise uncertainity due to lateral electron at higher energies.Master of Science (Hons)
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OLIVEIRA, CAMILA T. de. "Desenvolvimento de uma metodologia para calibração de câmaras de ionização de placas paralelas em feixes de raios X de energia baixa em termos de dose absorvida em água." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/26083.
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Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Pelz, Philipp M. [Verfasser], and R. J. Dwayne [Akademischer Betreuer] Miller. "Low-dose computational phase contrast transmission electron microscopy via electron ptychography / Philipp M. Pelz ; Betreuer: R.J. Dwayne Miller." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2018. http://d-nb.info/1173899243/34.
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Doucet, Robert. "Experimental verification of Monte Carlo calculated dose distributions for clinical electron beams." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33750.
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Current electron beam treatment planning algorithms are inadequate to calculate dose distributions in heterogeneous phantoms. Fast Monte Carlo algorithms are accurate in general but their clinical implementation needs validation. Calculations of electron beam dose distributions performed using the fast Monte Carlo system XVMC and the well-benchmarked general-purpose Monte Carlo code EGSnrc were compared with measurements. Irradiations were performed using the 9 MeV and 15 MeV beams from the Clinac 18 accelerator with standard conditions. Percent depth doses and lateral profiles were measured with thermoluminescent dosimeter and electron diode respectively. The accelerator was modelled using EGS4/BEAM, and using an experiment-based beam model. All measurements were corrected by EGSnrc calculated stopping power ratios. Overall, the agreement between measurement and calculation is excellent. Small remaining discrepancies can be attributed to the non-equivalence between physical and simulated lung material, precision in energy tuning, beam model parameters optimisation and detector fluence perturbation effects.
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Chan, Gordon Ho-Chi. "Beta and electron dose imaging using a microspectrophotometer system and radiochromic film." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0030/NQ66259.pdf.
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Chan, Gordon H. "Beta and electron dose imaging using a microspectrophotometer system and radiochromic film /." *McMaster only, 1999.
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Xing, Aitang. "Dosimetric Investigation of Electron Arc Therapy Delivered Using Siemens Electron Arc Applicator with a Trapezoidal Aperture." Thesis, University of Canterbury. Physics and Astronomy, 2007. http://hdl.handle.net/10092/1486.
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This study investigated the delivery of electron arc treatment with a trapezoidal aperture. The aim of the investigation is to reduce the nonuniformity of the dose distribution, which is caused by the variation of the patient contour from superior to inferior. The characteristics of static electron beam were first investigated. Then a measurement-based algorithm was developed and implemented as a computer program called EarcMU to calculate the monitor units required for delivering the prescribed dose with a trapezoidal aperture. The central axis percentage depth dose was found to be independent of source-to-surface distance (SSD) and the width of the aperture. The inplane profiles of a trapezoidal aperture show that the dose decreases longitudinally from the wide to the narrow end of the trapezoidal aperture. The EarcMU program was verified using two cylindrical water phantoms. The measured dose and the dose calculated by the program agreed within 2.1% in the typical clinical conditions. A simple method was also proposed for determining the trapezoidal aperture for an individual patient. Under the same conditions, the trapezoidal apertures calculated by this method along with the open aperture were used to deliver treatments to several conical phantoms. Significant improvement in the uniformity of dose distribution was observed. On average, the flatness index of the longitudinal dose distribution from superior to inferior decreases dramatically from 8% for open aperture down to 0.58% for trapezoidal aperture. The results are clinically significant, indicating that delivering the electron arc treatment using a trapezoidal aperture can bring more uniform dose to the patient regardless of the change of patient contour from superior to inferior.
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Uushona, Ndeshihafela Vera. "The effect of silicone gel breast prosthesis on the electron beam dose distribution." Thesis, University of Limpopo (Medunsa), 2009. http://hdl.handle.net/10386/253.
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Thesis --(MSc. (Medical Physics)), 2009.Introduction The primary role of breast cancer treatment with radiation is to deliver a sufficient radiation dose to the cancer cells without unduly causing biological damage to the healthy tissues. For over 50 years, electron beam therapy has been an important modality for providing an accurate dose of radiation to superficial cancers and disease and for limiting the dose to underlying normal tissues and structures in particular to boost the dose to the tumour bed and surgical scars after mastectomy. The Monte Carlo code MCNP5 was used to determine the effect of silicone gel breast prosthesis on the electron beam dose distribution. Materials and Method Percentage depth dose curves (PDD) for 6, 9, 12, and 15 MeV electron energies along the electron central axis depth dose distributions in a water phantom and with silicone prosthesis immersed in a water phantom were simulated using MCNP5. In order to establish the accuracy of the MCNP5 code, the depth dose curves obtained using MCNP5 were compared against the measured depth dose curves obtained from the Varian 2100C linear accelerator. The simulated depth dose curves with silicone prosthesis immersed in water were compared to the measured depth dose curves with the vi silicone prosthesis in water. The dose at the interface of the prosthesis with water was measured using thermoluminiscent dosimeters. Results The simulated and measured depth dose curve and the investigated dosimetric parameters are within 2%. Simulations in the presence of silicone showed a decrease in dose as the at the interface as the beam passes from the prosthesis to water for most energies however, for 15 MeV beam there is an increase in dose at the interface between the prosthesis and water and this was verified by physical measurements. Conclusion There were good correlations between the measured and MCNP simulated depth dose curve. Differences were in order of 2%. Small deviations occurred due to the fact that the simulations assumed a monoenergetic beam that exits the accelerator head, while in the measured results the beam exiting from the accelerator head includes scatted radiation from the collimators and the applicator. The presence of the prosthesis does not perturb the electron beam central axis depth dose curve however, the 15 MeV beam enhanced the dose in front of the interface between the prosthesis and water. Despite the limitations mentioned above MCNP5 results agree reasonably with the measured results. Hence, MCNP5 can be very useful in simulating electron percentage depth dose data.
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Yang, Yugu. "Feedback Control for Electron Beam Lithography." UKnowledge, 2012. http://uknowledge.uky.edu/ece_etds/9.
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Scanning-electron-beam lithography (SEBL) is the primary technology to generate arbitrary features at the nano-scale. However, pattern placement accuracy still remains poor compared to its resolution due to the open-loop nature of SEBL systems. Vibration, stray electromagnetic fields, deflection distortion and hysteresis, substrate charging, and other factors prevent the electron-beam from reaching its target position and one has no way to determine the actual beam position during patterning with conventional systems. To improve the pattern placement accuracy, spatial-phase-locked electron-beam lithography (SPLEBL) provides feedback control of electron-beam position by monitoring the secondary electron signal from electron-transparent fiducial grids on the substrate. While scanning the electron beam over the fiducial grids, the phase of the grid signal is analyzed to estimate the electron-beam position error; then the estimates are sent back to beam deflection system to correct the position error. In this way, closed-loop control is provided to ensure pattern placement accuracy. The implementation of spatial-phase-locking on high speed field-programmable gate array (FPGA) provides a low-cost method to create a nano-manufacturing platform with 1 nm precision and significantly improved throughput.
Shot-to-shot, or pixel-to-pixel, dose variation during EBL is a significant practical and fundamental problem. Dose variations associated with charging, electron source instability, optical system drift, and ultimately shot noise in the beam itself conspire to increase critical dimension variability and line width roughness and to limit the throughput. It would be an important improvement to e-beam patterning technology if real-time feedback control of electron-dose were provided to improve pattern quality and throughput even beyond the shot noise limit. A novel approach is proposed in this document to achieve the real-time dose control based on the measurement of electron arrival at the sample to be patterned, rather than from the source or another point in the electron-optical system. A dose control algorithm, implementation on FPGA, and initial experiment results for the real-time feedback dose control on the e-beam patterning tool is also presented.
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Aoyama, Takahiko, Shuji Koyama, Masatoshi Tsuzaka, and Hisashi Maekoshi. "A depth-dose measuring device using a multichannel scintillating fiber array for electron beam therapy." American Institute of Physics, 1997. http://hdl.handle.net/2237/7086.
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Lagmago, Kamta Gérard. "Evaluation of Eclipse© Monte Carlo dose calculation for clinical electron beams using heterogeneous phantoms." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40817.
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Accurate dose calculations of photon and electron transport in tissue materials are an important step in the appropriate delivery of cancer radiotherapy. Various commercial treatment planning systems used in radiotherapy provide algorithms for fast dose calculations. It is the responsibility of medical physicists to commission and evaluates these algorithms. In this work, we have evaluated the electron Monte Carlo (MC) algorithm in Eclipse using solid water phantoms with various tissue heterogeneities (water, lung, cortical bone, air) embedded, and using CT data from a real patient. For heterogeneous phantoms, the evaluation is done by comparing dose profiles and percent depth doses (PDDs) calculated on Eclipse with measurements, and with MC simulations using DOSXYZnrc. Measurements of dose profiles and PDDs are taken using EBT Gafchromic films, and we have developed a piece of software in Matlab for extracting dose from EBT Gafchromic films. For the real patient case, we use DOSXYZnrc results as a benchmark against which Eclipse is evaluated. Although Eclipse has been evaluated previously, the originality of the present work lays on the use of digitally reproduced phantom copies on Eclipse and DOSXYZnrc instead of CT scanned phantoms, the use of absolute dose for all comparisons, and the consideration of a real clinical patient. In addition, we have developed a tool for extracting absolute dose profiles and PDDs from EBT Gafchromic films. Our results indicate that, MC results agree in general better with measurements (within 5% or less) than Eclipse MC, whose discrepancies with measurements can be as high as 15% for physical phantoms used and as high as 10% in the case of real patient CT data. Largest discrepancies between measurement (or MC) and Eclipse MC occur at depths near and below tissue heterogeneities with relatively sharp density gradients. The slightly better performance of Eclipse for the real patient case is related to the smoother changes in heteroLes calculs précis de dose déposée dans les tissus par les photons et les électrons constituent une étape préliminaire cruciale dans tout approche de thérapie de cancer par la radiation. Plusieurs entreprises commerciales offrent de nos jours des programmes de planification des thérapies qui incluent des algorithmes de calcul de dose dans les tissus. Il est de la responsabilité du physicien médical de vérifier que ces algorithmes effectuent les calculs de dose avec une précision acceptables selon les standards actuels de radiothérapie. Dans ce mémoire, nous avons effectué une évaluation de l’algorithme Monte Carlo (MC) de calcul de dose (pour les faisceaux d’électrons) du programme de planification en radiothérapie connu sous le nom d’Eclipse. Dans cette évaluation, nous avons utilisé des fantômes solides contenant des tissue de densités diverses (eau, poumon, os, air) ainsi que des images scanner d’un patient réel (humain). Pour les fantômes solides notre évaluation a été faite en comparant les calculs d’Eclipse à des mesures expérimentales utilisant des films EBT Gafchromic d’une part, et d’autre part à des calculs MC plus rigoureux utilisant DOSXYZnrc. Pour le cas d’un patient, nous évaluons Eclipse en le comparant aux résultats MC obtenu via DOSXYZnrc, parce que nous ne pouvons placer un dosimètre à l’intérieur du patient. Nos résultats indiquent que les résultats MC sont plus proches des mesures expérimentales (écarts de l’ordre de 5% ou moins) que ceux d’Eclipse, lesquels ont un écart pouvant atteindre a peu près 15% par rapport aux mesures dans le cas des fantômes et 10% par rapport aux résultats MC pour le cas du patient réel. Les pires imprécisions d’Eclipse MC se retrouvent dans les tissus au voisinage des régions où il y a de fortes hetérogénéités et où les gradients de densités sont importants. En effet, les résultats obtenus par d’Eclipse MC pour le cas d’un patient ré
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ROGOVSCHI, VLADIMIR D. "Degradacao por radiacao de residuos biologicos (aflatoxinas) produzidos em Laboratorio de alimentos." reponame:Repositório Institucional do IPEN, 2009. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9464.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Schmidt, Heather Martin. "Improving the microbiological quality and safety of fresh-cut tomatoes by low dose electron beam irradiation." Thesis, Texas A&M University, 2004. http://hdl.handle.net/1969.1/2767.
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The effect of electron beam irradiation upon microbiological quality and safety of fresh-cut tomatoes was studied. Preliminary studies were conducted to ensure reliability of the rifampicin-resistant strain versus the parent strain of Salmonella serovar Montevideo for use in this study. Growth curve, heat tolerance and lactic acid resistance studies were performed, all of which showed no differences in behavior between the organisms. Fresh tomatoes were obtained from a local supplier and then cut into cubes with stem scars being separated. Both cubes and stem scars were inoculated with a rifampicin- resistant strain of either Salmonella Montevideo or Salmonella Agona, separated into treatment groups and treated by electron beam irradiation at 0.0 kGy (control), 0.7 kGy or 0.95 kGy. The effect of electron beam irradiation was determined for Salmonella, yeast, mold, and lactic acid bacteria (LAB) populations as well as pH on tomato cubes and stem scars over a 15-day storage period at 4??C. Results indicated that while irradiation treatment significantly reduced most microbial populations on tomato samples, there were no differences in the microbial populations between treatments of 0.7 kGy or 0.95 kGy. Irradiation at either dose resulted in a significant reduction of Salmonella Montevideo when compared to the control, with an initial reduction of 1.8 and 2.2 log10 CFU/g on tomatoes for 0.7 kGy and 0.95 kGy, respectively. LAB, yeasts and molds were more resistant to the treatment than Salmonella. Populations present on stem scars and tomato cubes did experience some differences in log reductions, possibly due to the protective effect of the stem scar on microorganisms. However, no differences were detected between the two Salmonella serotypes in response to irradiation treatment. This study indicates that doses of irradiation greater than 1 kGy should be used in fresh-cut tomatoes to eliminate significant populations of pathogens, as well as to ensure the microbial quality of the product. Additional studies also need to be conducted to examine the effects of higher irradiation doses on the sensory qualities of fresh-cut tomatoes.
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Moreno, Miriam Zarza. "Monte Carlo simulations for dosimetric verification in photon and electron beam radiotherapy." Doctoral thesis, Faculdade de Ciências e Tecnologia, 2012. http://hdl.handle.net/10362/7835.
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Dissertação para obtenção do Grau de Doutor em
Engenharia BiomédicaOne of the primary requirements for successful radiotherapy treatments is the accurate calculation of dose distributions in the treatment planning process. Monte Carlo (MC) dose calculation algorithms are currently recognized as the most accurate method to meet this requirement and to increase even further dose accuracy. The improvements in computer processor technology and the development of variance reduction techniques for calculations have led to the recent implementation and use of MC algorithms for radiotherapy treatment planning at many clinical departments. The work conducting to the present thesis consists of several dosimetric studies which demonstrate the potential use of MC dose calculations as a robust tool of dose verification in two different fields of external radiotherapy: electron and photon beam radiotherapy. The first purpose of these studies is to evaluate dose distributions in challenging situations where conventional dose calculation algorithms have shown some limitations and it is very difficult to measure using typical clinical dosimetric procedures, namely in regions containing tissue inhomogeneities, such as air cavities and bones, and in superficial regions. A second goal of the present work is to use MC simulations to provide a detailed characterization of photon beams collimated by a multileaf collimator (MLC) in order to assess the dosimetric influences of these devices for the MC modeling of Intensity Modulated Radiotherapy (IMRT) plans. Detailed MC model of a Varian 2100 C/D linear accelerator and the Millenium MLC incorporated in the treatment head is accurately verified against measurements performed with ionization chambers and radiographic films. Finally, it is also an aim of this thesis to make a contribution for solving one of the current problems associated with the implementation and use of the MC method for radiotherapy treatment planning, namely the clinical impact of converting dose-to-medium to dose-to-water in treatment planning and dosimetric evaluation. For this purpose, prostate IMRT plans previously generated by a conventional dose algorithm are validated with the MC method using an alternative method, which involves the use of non-standard CT conversion ramps to create CT-based simulation phantoms.
Fundação para a Ciência e Tecnologia; Centro de Física Nuclear da Universidade de Lisboa
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Royle, Georgina. "Towards quantitative intra-nuclear dose mapping of auger emitting radionuclides used for targeted radiotherapy." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:83c94d40-91a2-4175-b208-b5ea1bd5a207.
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Targeted radiotherapy (TRT) is a technique which allows for individual cancer cells to be targeted by radiation. However, there is variation in uptake at the whole body, organ, cellular and subcellular levels. This distribution affects the biological efficacy of the TRT agents. To address this problem, novel techniques have been developed and demonstrated. These aim to provide quantitative information about the spatial distribution of Auger electron (AE) emitting radiopharmaceuticals at the subcellular level. Two methods have been developed. The first, photoresist autoradiography (PAR), uses photoresists as an autoradiography substrate, and the second uses microautoradiography (MAR) and a transmission electron microscope (TEM). The techniques have been demonstrated using the AE emitter indium-111. Firstly, PAR is demonstrated using poly (methyl methacrylate) (PMMA). Photoresists were exposed to indium-111 which had been internalised into cells, and the photoresists were analysed using atomic force microscopy (AFM). The technique has a theoretical resolution in the nanometre range and was able to demonstrate cellular patterns on the micron scale. To gain quantitative information, the photoresist response (depth of pattern) was calibrated as a function of electron fluence and a model of the patterns was created. Combining the calibration data with the point source model allowed the position and intensity of the internalised source terms to be estimated using the PAR method. Secondly, a technique for electron microscope-microautoradiography (EM-MAR) was developed. The processing conditions of the MAR technique were determined and staining techniques developed, to produce high quality TEM micrographs. A time course experiment showed the distribution and variation in the uptake of the radiopharmaceutical at the cellular level. Both techniques are able to provide information about the subcellular distribution of the radioactivity at a higher resolution than current techniques. Both enable the collection of information which can be used in microdosimetric calculations.
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Lee, Sung-Woo. "Beta dose calculation in human arteries for various brachytherapy seed types." [College Station, Tex. : Texas A&M University, 2003. http://hdl.handle.net/1969.1/42.
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Thesis (Ph.D.)--Texas A&M University, 2003."Major Subject: Nuclear Engineering" Title from author supplied metadata (record created on Jul. 18, 2005.) Vita. Abstract. Includes bibliographical references.
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Olsson, Sara. "ESR dosimetry in the radiation therapy dose range : development of dosimetry systems and sensitive dosimeter materials /." Linköping : Univ, 2001. http://www.bibl.liu.se/liupubl/disp/disp2001/med701s.pdf.
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Mohamad, alabdoaburas Mohamad. "Etude dosimétrique et modélisation des composantes de la dose à distance pour les faisceaux d'électrons en radiothérapie externe." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS084/document.
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Les améliorations dans les procédures cliniques de radiothérapie ont conduit à des taux de survie élevés. En conséquence, les effets secondaires possibles de la dose délivrée aux tissus sains sont devenus une préoccupation croissante pour les radiothérapeutes. L’estimation de la dose aux tissus sains, y compris à distance du volume-cible présente un intérêt clinique croissant pour évaluer le risque aux structures sensibles situées hors du champ d’irradiation. Nos travaux antérieurs se sont focalisés sur l’évaluation la dose à distance des faisceaux de photons. La dose à distance due aux faisceaux d’électrons n’a jamais été prise en compte, ce qui peut conduire à des sous-estimations des doses à distance lorsque le traitement est fait entièrement ou partiellement par les électrons. C’est la raison pour laquelle, une étude approfondie de la dose à distance des faisceaux d’électrons est devenue indispensable. Dans le présent travail de thèse, nous avons dans un premier temps réalisé une étude expérimentale décrivant la dose à distance des faisceaux d’électrons de haute énergie produits par différents accélérateurs linéaires, équipés de différents types d’applicateurs. Nous avons analysé l’influence de différents paramètres du faisceau sur la dose à distance dont l’énergie du faisceau, la taille et le type de l’applicateur, la distance à l’axe du faisceau ainsi que la profondeur dans l’eau. Nous avons séparé la dose à distance en deux composantes principales : la dose due aux photons de bremsstrahlung et la dose due aux électrons diffusés. Ensuite, nous avons développé un modèle pour le calcul de la composante de la dose due aux photons de bremsstrahlung en tout point dans le patient, et un modèle pour le calcul de la dose due aux électrons diffusés en dehors du champ d’irradiation. Enfin, nous avons évalué l’application de nos modèles de calcul de dose à distance dans une situation clinique réelles afin de démontrer l’intérêt clinique de notre modélisation, l’objectif étant de mettre un point à terme, un outil logiciel innovant répondant à la fois aux besoins de l’optimisation de la radiothérapie moderne et à ceux de l’épidémiologie de la dose comme facteur de risque d’effets iatrogènesThe large improvements in the radiotherapy (RT) procedures have led to high survival rates. So the possible side late effects of the radiotherapy due to the doses deposited into the normal tissues have become a growing concern for the radio-oncologists. The assessment of the dose outside the radiation field presents an important clinical benefit for estimating the risk at sensible structures situated partially or entirely outside the radiation field, especially in pediatric, pregnant patients or the patients having cardiac implantable devices. More understanding of side effects of RT will require not only improved control of the high doses delivered to the target volumes, but also better knowledge of the unintended but unavoidable lower doses delivered out of the target. In this context, most studies on out-of-field dose estimation focus on photon beams. Nevertheless, electron beams are still an important component of RT, for treating superficial tumors (at depths < 5 cm). The out-of-field dose from electron beams has never been taken account, which causes an under estimation of this dose when the radiotherapy is done only or partly by the electrons. For this reason, a detailed investigation of the out-of-field dose from electron beams is essential for better estimation of the out-of-field dose regardless the radiotherapy type. In this thesis, we have experimentally evaluated the out-of-field doses in high-energy electron beams for three linear accelerators equipped with different electron applicator types used in daily practice. The dependence of this dose on different parameters, such as the applicator size, the electron beam energy, the depth, and the off-axis distance have been investigated. The scattered electrons component and the bremsstrahlung photons component have been separated by a semi-experimental method. We have developed a multi-source model based on existing multi-scattering models for calculating the bremsstrahlung dose distribution at any point in the patient inside and outside the radiation field. We have also analytically calculated the scattered electrons dose distribution outside the radiation field. These two models permit to calculate the total out-of-field dose from electron beams anywhere in the patient. Finally, we have evaluated the application of our models of dose calculation in a real clinical situation in order to validate our software, the aim being to set up an innovative software tool, meeting both the needs of radiotherapy and epidemiology of the dose as a risk factor for iatrogenic effects
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Moji, Kabelo McDonald. "Comparison of measured photon and electron beam dose distributions between 3D water phanton and profiler 2 scanning system, South Africa." Thesis, University of Limpopo (Medunsa Campus), 2013. http://hdl.handle.net/10386/1086.
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Thesis ( MSc ( Physics) ) -- University of Limpopo, 2013.Background and Objectives: To establish whether the profiler 2 scanning system can be used as a substitute for the 3D-water phantom, by comparing the percentage depth doses and beam profiles for both the photons and electron beams, and validating the results using CMS XiO treatment planning system. Methods: Beam data (profiles, percentage depth doses and absolute dosimetry) were acquired for the two systems: (3D-water phantom and profiler 2 scanning system) for beam energies 6 MV and 15 MV photon beams, and 4, 6, 8, 10, 12 and 15 MeV electron beams generated by the Elekta Synergy linear accelerator (linac) for the field sizes of 6 × 6 cm2, 10 × 10 cm2, 14 × 14 cm2, 20 × 20 cm2, and 25 × 25 cm2 at depths of 0.5 cm, 1.0 cm, 2.0 cm, and 5.0 cm respectively. These measurements were acquired using ionization chambers in water and diode detectors in Perspex. The acquired data was sent to CMS XiO treatment planning system for validation. Results: In general, the dose distributions for both systems compared very well with uncertainties within recommended limits. The largest maximum difference in symmetry was 1.6 % for a 6 MV photon beam defined at 25 × 25 cm2 field size. The largest maximum difference in flatness was 2.77 % for a 4 MeV electron beam defined at 10 × 10 cm2 applicator size. The penumbra largest maximum difference was 1.708 cm for 8 MeV electron beam defined at 25 × 25 cm2 applicator size, which was outside the recommended limit of 1.2 cm. The largest maximum difference in field size was 2.388 cm for a 6 MeV electron beam defined at 20 × 20 cm2 applicator size, which was outside the recommended limit of 0.4 cm. The largest maximum difference in percentage depth dose at 10 cm depth was 1.69 % for the 6 MV photon beam. The absolute dose output measurements showed a very good agreement between the two systems to a maximum percentage difference and highest standard deviation of -0.99 % and 0.69 % respectively for the 6 MV photon beam. Validation measurements showed an agreement to less than 1 % and 2 mm for percentage depth doses and beam profiles respectively. Conclusion and recommendation: From the results obtained, it is evident that the profiler 2 scanning system can be used as a substitute for the 3D-water phantom beam data acquisitions during linear accelerator commissioning. The future work based on this study could be to study the limitations involved with the profiler 2 scanning system when used during measurements for commissioning of a linear accelerator. Limitations like field size (maximum field size of 20 × 30 cm2 at SSD = 100 cm), number of Perspex slabs to be used on top of the profiler 2 scanning system and diagonal profile measurements.
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Stewart, Kristin Joy. "The development of new devices for accurate radiation dose measurement: a guarded liquid ionization chamber and an electron sealed water calorimeter." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18423.
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In this work we developed two new devices that aim to improve the accuracy of relative and reference dosimetry for radiation therapy: a guarded liquid ionization chamber (GLIC) and an electron sealed water (ESW) calorimeter. With the GLIC we aimed to develop a perturbation-free energy-independent detector with high spatial resolution for relative dosimetry. We achieved sufficient stability for short-term measurements using the GLIC-03, which has a sensitive volume of approximately 2 mm3. We evaluated ion recombination in pulsed photon beams using a theoretical model and also determined a new empirical method to correct for relative differences in general recombination which could be used in cases where the theoretical model was not applicable. The energy dependence of the GLIC-03 was 1.1% between 6 and 18 MV photon beams. Measurements in the build-up region of an 18 MV beam indicated that this detector produces minimal perturbation to the radiation field and confirmed the validity of the empirical recombination correction. The ESW calorimeter was designed to directly measure absorbed dose to water in clinical electron beams. We obtained reproducible measurements for 6 to 20 MeV beams. We determined corrections for perturbations to the radiation field caused by the glass calorimeter vessel and for conductive heat transfer due to the dose gradient and non-water materials. The overall uncertainty on the ESW calorimeter dose was 0.5% for the 9 to 20 MeV beams and 1.0% for 6 MeV, showing for the first time that the development of a water-calorimeter-based standard for electron beams over a wide range of energies is feasible. Comparison between measurements with the ESW calorimeter and the NRC photon beam standard calorimeter in a 6 MeV beam revealed a discrepancy of 0.7±0.2% which is still under investigation. Absorbed-dose beam quality conversion factors in electron beams were measured using the ESW calorimeter for the Exradin A12 and PTW Roos ionizationDans ce travail nous avons développé deux nouveaux détecteurs qui visent à améliorer l'exactitude de la dosimétrie relative et de référence en radiothérapie: une chambre d'ionisation liquide gardée (GLIC) et un calorimètre d'eau scellé pour les électrons (ESW). Avec la GLIC nous avons visé à développer un détecteur indépendant de l'énergie et libre de perturbations avec une résolution spatiale élevée pour la dosimétrie relative. Nous avons atteint une stabilité suffisante pour des mesures à court terme en utilisant la GLIC-03, qui a un volume sensible d'approximativement 2 mm3. Nous avons évalué la recombinaison générale des ions dans des faisceaux de photons pulsés en utilisant un modèle théorique et nous avons également déterminé une nouvelle méthode empirique, permettrant de corriger pour les différences relatives de recombinaison générale, qui pourrait être employée dans les cas où le modèle théorique ne serait pas applicable. La dépendance d'énergie du GLIC-03 était 1.1% dans des faisceaux de photon entre 6 et 18 MV. Les mesures dans la région de déséquilibre électronique ('build-up') d'un faisceau du 18 MV ont indiqué que ce détecteur introduit une perturbation minimale du champ de rayonnement et ont confirmé la validité de la correction empirique de recombinaison. Le calorimètre ESW a été conçu pour mesurer directement la dose absorbée dans les faisceaux d'électrons cliniques. Nous avons obtenu des mesures reproductibles pour des faisceaux de 6 à 20 MeV. Nous avons déterminé les corrections nécessaires pour tenir compte des perturbations du champ de rayonnement introduites par le récipient de verre du calorimètre et du transfert thermique de conduction dû au gradient de dose et au fait que les matériaux ne sont pas de l'eau. L'incertitude globale sur la dose pour le calorimètre ESW était 0.5% pour les faisceaux de 9 à 20 MeV et 1.0% pour 6 MeV, prouvant pour la première fois que le d
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CINTRA, FELIPE B. de. "Avaliacao da metodologia de calculo de dose em microdosimetria com fontes de eletrons com o uso do codigo MCNP5." reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9619.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Jarry, Geneviève. "Study of novel techniques for verification imaging and patient dose reconstruction in external beam radiation therapy." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103025.
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Treatment delivery verification is an essential step of radiotherapy. The purpose of this thesis is to develop new methods to improve the verification of photon and electron beam radiotherapy treatments. This is achieved through developing and testing (1) a way to acquire portal images during electron beam treatments, (2) a method to reconstruct the dose delivered to patients during photon beam treatments and (3) a technique to improve image quality in kilovoltage (kV) cone beam computed tomography (CBCT) by correcting for scattered radiation. The portal images were acquired using the Varian CL21EX linac and the Varian aS500 electronic portal imaging device (EPID). The EGSnrc code was used to model fully the CL21EX, the aS500 and the kV CBCT system.We demonstrate that portal images of electron beam treatments with adequate contrast and resolution can be produced using the bremsstrahlung photons portion of the electron beam. Monte Carlo (MC) calculations were used to characterize the bremsstrahlung photons and to obtain predicted images of various phantoms. The technique was applied on a head and neck patient.
An algorithm to reconstruct the dose given to patients during photon beam radiotherapy was developed and validated. The algorithm uses portal images and MC simulations. The primary fluence at the detector is back-projected through the patient. CT geometry to obtain a reconstructed phase space file. The reconstructed phase space file is used to calculate the reconstructed dose to the patient using MC simulations. The reconstruction method was validated in homogeneous and heterogeneous phantoms for conventional and IMRT fields.
The scattered radiation present in kV CBCT images was evaluated using MC simulations. Simulated predictions of the scatter distribution were subtracted from CBCT projection images prior to the reconstruction to improve the reconstructed image quality. Reducing the scattered radiation was found to improve contrast and reduce shading artifacts.
MC simulations, in combination with experimental techniques, have been shown to be valuable tools in the development of treatment verification methods. The three novel methods presented in this thesis contribute to the improvement of radiotherapy treatment verification. They can potentially improve treatment outcome by ensuring a better target coverage.
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Rech, Amanda Burg. "Avaliação de dose administrada no tratamento de neoplasia ginecológica por ressonância de spin eletrônico com L-alanina." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-01082012-145158/.
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Neoplasias ginecológicas são os tumores de maior incidência no público feminino. Como alternativa para o tratamento destes tumores existe a radioterapia, em que a sua eficácia depende prioritariamente da correta administração da dose prescrita ao tumor, com acurácia de ±5%, conforme estabelecido pela American Association of Physicists in Medicine (AAPM). Para verificar a administração de doses existem diversas técnicas dosimétricas, entre elas a ressonância de spin eletrônico (RSE) com L-alanina, material tecido-equivalente, que relaciona dose com a quantidade de radicais livres formados pela radiação. Portanto, o objetivo deste estudo é a verificação da dose administrada na região tumoral de pacientes diagnosticadas com câncer ginecológico submetidas à teleterapia, utilizando L-alanina e a RSE. Para comparação entre as modalidades de radioterapia, foi realizada braquiterapia ginecológica com objeto simulador, verificando a dose no reto durante o tratamento, que deve ser inferior a 65% da dose prescrita ao tumor, conforme a International Commission on Radiation Units (ICRU). Para a análise de teleterapia foi construído um aparato, para a inserção vaginal do material radio-sensível, que foi utilizado durante 5 das 25 sessões de tratamento. As doses foram determinadas com o sistema de planejamento do tratamento mediante as imagens da tomografia computadorizada, em conjunto com softwares de planejamento, e a existência de marcadores radiopacos no aparato permitiu a confirmação das doses, conforme referência óssea através de imagens de portal feitas no momento anterior ao tratamento. Após a irradiação foi feita a leitura das amostras com o espectrômetro de RSE, em que a amplitude pico a pico da linha principal do sinal, normalizado pela massa, determinou a dose entregue nas regiões de interesse. Previamente ao estudo in vivo foi efetuada a teleterapia com objeto simulador, nas mesmas condições de tratamentos in vivo, apresentando desvio médio em relação ao planejamento de (0,2 ± 3,5)%, viabilizando o estudo com pacientes. Para a primeira paciente o desvio médio obtido foi de (0,5 ± 3,7)% e para a segunda de (-0,7 ± 2,8)%. Na simulação da braquiterapia o desvio médio observado foi de (-1,3 ± 9,2)%. Por causa do pequeno número amostral de pacientes, esta pesquisa é classificada como um estudo de viabilidade, em que a utilização de L-alanina com a RSE se mostrou eficiente para o objetivo proposto, fazendo com que os resultados da teleterapia estivessem de acordo com o estipulado pela AAPM e na braquiterapia a dose administrada no reto obedecesse ao relatório 38 da ICRU.Gynecological malignancies are the most incident female tumors. As an alternative treatment for these tumors exist the radiotherapy, which their effectiveness mainly depends on the right administration of the prescribed dose to the tumor, with an accuracy of ±5%, as established by the American Association of Physicists in Medicine (AAPM). There are a lot of dosimetric techniques for dose verification, including electron spin resonance (ESR) with L-alanine, a tissue-equivalent material, which relates dose with the amount of free radicals formed by radiation. Therefore, the aim of this study is to verify the dose administered in the tumor of patients diagnosed with gynecological cancer subjected to external beam radiation therapy using L-alanine and ESR. For comparison between the radiotherapy modalities was performed gynecological brachytherapy in phantom, verifying the dose to the rectum during treatment, which must be less than 65% of the prescribed dose to the tumor, according to the International Commission on Radiation Units (ICRU). For teletherapy analysis was constructed an apparatus for vaginal insertion of the radio-sensitive material, which was used in 5 of the 25 treatment fractions. The doses were determined with the treatment planning system with the computed tomography images, together with the planning software, and the existence of radiopaque markers in the apparatus allowed the dose confirmation, according to the bone reference through portal images made before treatment. After the irradiation the samples was read with the ESR spectrometer, wherein the peak to peak amplitude of the signal main line, normalized by weight, determined the dose delivered into the regions of interest. Prior to the in vivo study was performed the teletherapy with phantom, under the same conditions of in vivo treatments, presenting mean deviation to the planning dose of (0.2 ± 3.5)%, enabling the study with patients. For the first patient, the mean deviation obtained was of (0.5 ± 3.7)% and for the second one of (-0.7 ± 2.8)%. In the brachytherapy simulation the mean deviation observed was of (-1.3 ± 9.2)%. Due to the small sample of patients, this research is classified as a feasibility study, which the use of L-alanine with the ESR was efficient for the objective proposed, making the teletherapy results consistent with the stipulated by the AAPM, and in the brachytherapy the dose to the rectum obey the ICRU report 38.
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Chinaglia, Dante Luis. "O deslocamento do segundo ponto de cruzamento na curva de emissão eletrônica de polímeros com a dose de irradiação absorvida e suas implicações." Universidade de São Paulo, 1992. http://www.teses.usp.br/teses/disponiveis/54/54132/tde-21072009-172318/.
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Amostras de Teflón® FEP e Mylar C foram submetidas a um bombardeio eletrônico por longos períodos a fim de se verificar a existência de uma possível corrente de condução na fase final de um carregamento por feixe eletrônico. Em vez disso, descobriu-se que a energia associada ao segundo ponto de cruzamento da curva de emissão eletrônica do material bombardeado varia lentamente com o tempo de exposição à irradiação. Por outro lado foram descobertos também fortes indícios de que o centróide de carga sofre um deslocamento enquanto a amostra está sendo irradiada. A componente da corrente através da amostra, associada a qualquer um desses efeitos se superpõe à corrente de condução (se existir) e acaba tornando inviável a sua observação, enquanto um ou ambos os efeitos persistirem. Na realidade não é só a energia do segundo ponto de cruzamento que varia; toda a curva de emissão característica do material, que é fundamental para se entender os processos e carga e descarga de amostras, sofre modificação com a irradiação prolongada. Além disto, dois novos métodos para se carregar uma amostra de polímero estão sendo propostos. Um deles permite carregar uma amostra positivamente, por etapas, a tensões mais elevadas que o método convencional. O outro possibilita carregar negativamente uma amostra, lançando mão do mecanismo de auto-regulação para interrupção do processo de carga, o que só havia sido feito até o momento para um carregamento positivo. Um novo método para se descarregar uma amostra usando o próprio feixe eletrônico também é apresentado.Teflon® FEP and Mylar C samples were submitted to an electron beam during long periods of time in order to examine the possible existence of conduction current in the final stages of the charging process. It was found that the energy associated with the second crossover point in the electronic emission curve of the irradiated material varied slightly with the time of irradiation. On the other hand, strong evidence emerged that the charge centroid is shifted while the sample is being irradiated. The component of the current through the sample which is associated with any of these effects is superimposed to the conduction current (if present), hampering the identification of a conduction current. In fact, it is not only the energy of the second crossover point that varies, for the whole emission curve is modified upon prolonged irradiation. This emission curve is fundamental for understanding the charging and discharging processes in the samples. In addition, two new methods for charging a sample are being proposed. The first allows one to charge the sample positively to surface potentials that are higher than those obtained in the conventional method. The other method permits the sample to be charged negatively using the auto-regulation mechanism for interrupting the charging process; this had previously been done only for charging samples positively. A new method for discharging a sample using the electron beam is also presented.
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GROPPO, DANIELA P. "Caracterização dosimétrica de amostras de BeO em feixes de radiação alfa, beta e X por técnicas luminescentes." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10576.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
28
Olofsson, Lennart. "Energy and intensity modulated radiation therapy with electrons." Doctoral thesis, Umeå : Department of Radiation Sciences, Radiation Physics, Umeå University, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-491.
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Albaret, Claude. "Automated system for Monte Carlo determination of cutout factors of arbitrarily shaped electron beams and experimental verification of Monte Carlo calculated dose distributions." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81259.
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Dose predictions by Monte-Carlo (MC) techniques could alleviate the measurement load required in linac commissioning and clinical radiotherapy practice, where small or irregular electron fields are routinely encountered. In particular, this study focused on the MC calculation of cutout factors for clinical electron beams. A MC model for a Varian linac CL2300C/D was built and validated for all electron energies and applicators. A MC user code for simulation of irregular cutouts was then developed and validated. Supported by a home-developed graphical user interface, it determines in situ cutout factors and depth dose curves for arbitrarily shaped electron fields and collects phase space data. Overall, the agreement between simulations and measurements was excellent for fields larger than 2 cm.The MC model was also used to calculate dose distributions with the fast MC code XVMC in CT images of phantoms of clinical interest. These dose distributions were compared to dose calculations performed by the pencil-beam algorithm-based treatment planning system CadPlan and verified against measurements. Good agreement between calculations and measurements was achieved with both systems for phantoms containing 1-dimensional heterogeneities, provided a minimal quality of the CT images. In phantoms with 3-dimensional heterogeneities however, CadPlan appeared unable to predict the dose accurately, whereas MC provided with a more satisfactory dose distribution, despite some local discrepancies.
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POLI, MARIA E. R. "Dosimetria aplicada na irradiacao de toda a pele utilizando feixes de eletrons com energia nominal de 4 MeV." reponame:Repositório Institucional do IPEN, 2000. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10813.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
31
KOIKE, AMANDA C. R. "Compostos bioativos em flores comestíveis processadas por radiação." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/23907.
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Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
32
Cardoso, Ana Paula Ferragut [UNESP]. "Estudo dose-resposta do herbicida diuron[3-(3,4-diclorofenil)-1,1-dimetiluréia] no epitélio da bexiga de ratos Wistar machos." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/95891.
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cardoso_apf_me_botfm.pdf: 463235 bytes, checksum: f5c3dd035d2b9e83db6356001aa70012 (MD5)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] is a herbicide that in a previous longterm study with Wistar rats fed at 2,500 ppm concentration showed high incidence of urothelial tumors in both genders. Accordingly, USEPA categorized Diuron as a “known/likely” human carcinogen. The accepted non-genotoxic mode of action (MOA) of Diuron encompasses urothelial necrosis induced by direct cytotoxicity, followed by regenerative cell proliferation and sustained urothelial hyperplasia that may favor neoplasia development. Scanning electron microscopy (SEM), light microscopy and labeling index are essentials tools for identification and classification of cytotoxic and proliferative changes in the bladder. The present study evaluated the dose-response of Diuron regarding urothelial lesions. Sixty male Wistar rats were fed Diuron for 20 weeks mixed in the diet at 0, 60, 125, 500, 1,250, or 2,500 ppm. Simple hyperplasia was significantly increased in the Diuron 1,250 and 2,500 ppm groups, and the cell proliferation at 2,500 ppm group. By SEM, the incidences and severity of lesions were significantly greater in the 500 and 1,250 ppm. Although numerically increased, the incidence of lesions in the 2,500 ppm group did not differ significantly from the control. The present study documented a doseresponse influence of Diuron on the rat urothelium, with a no observed effect level (NOEL) of 125 ppm.
33
ISOLDI, ANA B. G. "Estudo do efeito da dose de radioesterilizacao sobre as propriedades do poli(tereftalato de etileno) - PET reciclado." reponame:Repositório Institucional do IPEN, 2003. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11134.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
34
BANADOS, PEREZ HOMERO E. "Desenvolvimento de um sistema calorimetrico para dosimetria de feixes de eletrons em processos por radiacao." reponame:Repositório Institucional do IPEN, 1994. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10356.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
35
FONSECA, GABRIEL P. "Projeto e construcao de placas espalhadoras e degradadoras de energia para uso em radioterapia com feixe de eletrons para doencas de pele." reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9550.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
36
Wan, Jui. "Exploring RayStation Treatment Planning System: Commissioning Varian TrueBeam Photon and Electron Energies, and Feasibility of Using FFF Photon Beam to Deliver Conventional Flat Beam." University of Toledo Health Science Campus / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=mco1501843246429305.
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ANTUNES, PAULA C. G. "Reconstrucao de objetos simuladores segmentados aplicaveis a dosimetria de pele." reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9614.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
38
Ruiz, González Néstor A. "Use of GAFCHROMIC® EBT film for in-water measurements of surface dose, buildup region, and other dosimetric parameters of 6, 9, 12, 16, and 20 MeV electron beams a thesis /." San Antonio : UTHSC, 2008. http://learningobjects.library.uthscsa.edu/cdm4/item_viewer.php?CISOROOT=/theses&CISOPTR=38&CISOBOX=1&REC=1.
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Cardoso, Ana Paula Ferragut. "Estudo dose-resposta do herbicida diuron[3-(3,4-diclorofenil)-1,1-dimetiluréia] no epitélio da bexiga de ratos Wistar machos /." Botucatu : [s.n.], 2010. http://hdl.handle.net/11449/95891.
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Orientador: Maria Luiza Cotrim Sartor de OliveiraBanca: Carlos Márcio Nóbrega de Jesus
Banca: Heidge Fukumasu
Não disponível
Abstract: Diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] is a herbicide that in a previous longterm study with Wistar rats fed at 2,500 ppm concentration showed high incidence of urothelial tumors in both genders. Accordingly, USEPA categorized Diuron as a "known/likely" human carcinogen. The accepted non-genotoxic mode of action (MOA) of Diuron encompasses urothelial necrosis induced by direct cytotoxicity, followed by regenerative cell proliferation and sustained urothelial hyperplasia that may favor neoplasia development. Scanning electron microscopy (SEM), light microscopy and labeling index are essentials tools for identification and classification of cytotoxic and proliferative changes in the bladder. The present study evaluated the dose-response of Diuron regarding urothelial lesions. Sixty male Wistar rats were fed Diuron for 20 weeks mixed in the diet at 0, 60, 125, 500, 1,250, or 2,500 ppm. Simple hyperplasia was significantly increased in the Diuron 1,250 and 2,500 ppm groups, and the cell proliferation at 2,500 ppm group. By SEM, the incidences and severity of lesions were significantly greater in the 500 and 1,250 ppm. Although numerically increased, the incidence of lesions in the 2,500 ppm group did not differ significantly from the control. The present study documented a doseresponse influence of Diuron on the rat urothelium, with a no observed effect level (NOEL) of 125 ppm.
Mestre
40
MELO, ANA M. M. de A. "Estudos dos efeitos da radiacao gama de sup60Co sobre larvas de Biomphalaria glabrata (Say,1818)." reponame:Repositório Institucional do IPEN, 1998. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9270.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
41
Emelianova, Olga. "Modeling gas-driven microstructural evolution in ODS-EUROFER steel by high dose helium and hydrogen ion implantation." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP056.
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Les aciers ferritiques-martensitiques renforcés par dispersion d'oxydes (ODS) sont des matériaux de structure de haute performance pour les futures installations nucléaires de fission et de fusion. Un problème important pour la performance de ces aciers sous irradiation est leur résistance aux effets néfastes des gaz de transmutation, l'hélium et l'hydrogène, avec une attention particulière aux effets liés à la forte densité de nanoparticules d'oxyde. L'objectif de la thèse est une étude systématique et fondamentale de l’évolution de la microstructure induite par les gaz légers dans les aciers ODS ferritiques-martensitiques en fonction de la teneur en gaz accumulée, du taux d'endommagement et de la température, en accordant une attention particulière au rôle des nanoparticules d'oxyde. L'approche expérimentale utilisée a consisté à saturer des échantillons avec différentes quantités d'hélium et d'hydrogène, par implantation ionique à JANNuS-Orsay, dans des conditions bien contrôlées. Le matériau de référence utilisé était l'acier ODS-EUROFER. Les modifications microstructurales accompagnant l'accumulation de gaz ont été révélées par microscopie électronique à transmission. Pour une meilleure compréhension des mécanismes d’interaction de l’hélium avec les nanoparticules d’oxyde, les expériences ont été complétées par des implantations ioniques dans un système modèle de couches minces Y₂O₃/FeCr, et par une modélisation analytique et numérique pertinente. Cependant, leurs contributions au gonflement sont généralement relativement mineures par rapport aux autres populations de bulles. Au contraire, les grosses bulles comportent le risque d'une transition accélérée d’une bulle à une cavité dans des conditions défavorables, ce qui provoque un gonflement non contrôlé des cavités. La viabilité d'un tel effet a été démontrée dans des expériences d'implantation d’ions He et d’irradiation d’ions Au simultanées, et quantifiée à l'aide d'une modélisation analytique. Lors de l'implantation séquentielle d'hélium et d'hydrogène dans l'acier ODS-EUROFER, une augmentation notable de l'absorption d'hydrogène a été observée par rapport à l'acier ne contenant pas d’oxyde. Cependant, la résistance globale à l’irradiation de l'acier n'a été que faiblement influencée par l'hydrogène, aussi bien dans l'acier ODS-EUROFER que dans le système modèle Y₂O₃/FeCr. Les effets visibles de l'hydrogène sur la microstructure des bulles étaient mineurs et ne se manifestaient qu'après l'implantation d’H à température ambiante. En résumé, l’acier ODS s’avère résistant au gonflement jusqu’à des niveaux très élevés d’hélium et d’hydrogène accumulés. La présence de nano-oxydes à haute densité est généralement bénéfique pour la tolérance à l’irradiation de l'acier, mais leur influence n'est pas aussi forte que celle attendue. Le piégeage de l’hydrogène dans les bulles d’hélium ne présente aucun risque potentiel pour la tolérance à l’irradiation de l’acier ODS dans les conditions expérimentales étudiéesOxide dispersion strengthened (ODS) ferritic-martensitic steels are advanced high-performance structural materials for next generation nuclear and fusion facilities. An important issue for operation performance of these steels is their resistance to detrimental effects of transmutation gases, helium and hydrogen, with a particular attention to the effects from dense population of nano-size oxide particles. The objective of the thesis is a systematic investigation of fundamental trends in gas-driven microstructure development in ferritic-martensitic ODS steels in reply to variations in the accumulated gas content, gas accumulation and damage rates, and temperature, with particular attention to the role of oxide particles. The applied experimental approach involved saturation of steel samples with various amounts of helium and hydrogen atoms using ion implantation at the JANNuS-Orsay facility in well-controlled conditions. The reference material used was ODS-EUROFER steel. The microstructural changes accompanying gas accumulation were revealed using transmission electron microscopy (TEM). For the better understanding of the mechanisms of helium interaction with oxide particles, the experiments were backed up with ion implantation into a model Y₂O₃/FeCr bilayer system and with relevant analytical and numerical modeling. Microstructural investigations of ODS-EUROFER samples implanted to high He fluences reveal a persistent partitioning of introduced gas between different microstructural features. In addition to gas bubbles in the grain bulk, extensive bubble precipitation on extended defects (grain boundaries and dislocations) and precipitates (carbides and oxides) was observed. The relative abundance of bubbles associated with different microstructural features is found to be sensitive to implantation conditions and changes in uncorrelated manner with the variation of implantation parameters. Overall, the main contributions to steel volume expansion (swelling) and the He inventory were from bubbles on grain boundaries and, at lower implantation temperatures and higher fluxes, from bubbles in the grain matrix. However, the preferential He accumulation at grain boundaries does not lead to bubble coalescence and growth of huge grain boundary cavities, without causing high-temperature helium embrittlement. Oxide nanoparticles were found to be efficient centers for helium bubble nucleation, each hosting a single bubble typically noticeably larger than bubbles in other populations. However, their contributions to both swelling and He inventory were estimated to be generally relatively minor as compared to other bubble populations, implying that oxide particle provide no substantial improvement of steel radiation performance. On the contrary, the large bubbles bear the risk of accelerated bubble-to void transition in unfavorable conditions, launching uncontrolled void swelling. The viability of such effect was demonstrated in experiments on simultaneous steel implantation with He and Au ions and quantified using analytical modeling. Under sequential helium and hydrogen implantation into ODS-EUROFER steel, notable increase of hydrogen uptake was observed as compared to oxide-free steel. However, the parameters of He bubble microstructure and, hence, the overall steel radiation resistance were found to be only weakly influenced by hydrogen, in both ODS-EUROFER steel and in Y₂O₃/FeCr bilayer system. Visible hydrogen effects on bubble microstructure were minor and manifested only after the room temperature H implantation. Summing up, ODS steel is shown to be resistant to void swelling up to very high levels of accumulated helium and hydrogen. The presence of high density of nano-oxides is generally beneficial for steel radiation tolerance, but their influence is not as strong as commonly expected. Hydrogen trapping in helium bubbles doesn’t manifest any potential risks for ODS steel radiation tolerance under experimental conditions studied
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James, Anthony. "Développement de méthodes de caractérisation chimiques de surface en support à l’amélioration des procédés de la microélectronique avancée." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10097/document.
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L'objectif principal de ce travail de thèse a été de développer des méthodologies d'analyse de surface fiables pour caractériser divers nouveaux matériaux intégrés dans des structures de très faibles dimensions caractéristiques des développements actuels de la microélectronique. Un intérêt particulier a été porté sur l'utilisation combinée de plusieurs techniques complémentaires. Une première étude a porté sur les artefacts de caractérisation de couches isolantes (dioxyde de silicium et dioxyde de silicium dopé au fluor – FTEOS) situées entre les niveaux de métallisation des puces. Une étude systématique des effets de la dose électronique liée à une analyse AES a été réalisée en utilisant la complémentarité des techniques AES/XPS. Les résultats ont révélé des changements chimiques en extrême surface (sous-oxydes) dépendant de la nature du matériau. La seconde étude a porté sur la mise en oeuvre d'une méthodologie analytique pour la caractérisation de la couche de passivation formée sur les flancs de gravure après deux gravures plasma successives sur des structures de très faibles dimensions (lignes de 300 nm et tranchées de 200 nm). Cette méthodologie a été basée sur l'utilisation de l'effet de charge différentiel, observé lors d‘analyses simultanées de deux matériaux de propriétés électriques différentes, ainsi que sur la complémentarité des caractérisations par XPS et ToF-SIMS y compris des analyses XPS résolues en angles (AR-XPS). La composition chimique de l'extrême surface de la couche de passivation a ainsi pu être déterminée sur des parois verticales. La surface de cette couche a révélé être composée principalement par de l'oxygène ayant réagi avec le silicium pour former des sous-oxydes de silicium de différentes stoechiométriesThe main goal of this thesis was to develop reliable surface analysis methods to characterize various new materials used in very small size structures typical of current developments in microelectronics applications. A particular interest has been taken in combining several complementary techniques. The first study was focused on potential artifacts when characterizing insulating layers (silicon dioxide and fluorine doped silicon dioxide – FTEOS) which are used between metal layers in chips. A comprehensive study of the electron dose effects in AES was performed using complementary AES and XPS techniques. The results revealed chemical changes in the outermost surface (suboxides) that depend on the nature of the material. The second study was focused on the development of an analytical methodology to characterize the passivation layer on the etch sidewalls after two successive plasma etching processes applied onto very small size structures (300 nm lines and 200 nm trenches). This methodology was based on the use of the differential charging effect that takes place when analyzing simultaneously two materials exhibiting different electrical properties and on the complementarity of ToF-SIMS and XPS characterizations including angular resolved XPS (AR-XPS). The chemical composition of the outermost surface of the sidewall passivation layer could then be determined. The surface of that layer was found to be consisting mostly from oxygen than reacted with silicon to form silicon suboxides with various stoichiometries
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Fauré, Joël. "Etude de surfaces monocristallines de silicium par reflexion d'electrons : degradation par implantation d'ions argon, reorganisation par recuit." Toulouse 3, 1987. http://www.theses.fr/1987TOU30108.
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Etude de la degradation de la surface plane si(111) par implantation d'ions ar**(+) a temperature ambiante. Lorsque la dose d'ions implantes augmente, l'intensite des taches du diagramme de diffraction diminue progressivement et les marches atomiques, observees en microscopie electronique par reflexion, disparaissent. Lorsque l'energie incidente des ions ar**(+) augmente, la vitesse de degradation de la surface diminue. Apres disparition complete des marches atomiques, un recuit thermique "in situ" de quelques minutes a 575**(o)c permet de retrouver la topographie de la surface initiale. Le recuit provoque la desorption complete de l'argon implante et de retour en sites des atomes de la surface
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PEREIRA, LILIAN N. "Uso de diodos epitaxiais de Si em dosimetria de fótons." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10581.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Perrot, Yann. "Evaluation de la dose déposée par des faisceaux d'électrons en radiothérapie dans des fantômes voxelisés en utilisant la plateforme de simulation Monte Carlo GATE fondée sur GEANT4 dans un environnement de grille." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2011. http://tel.archives-ouvertes.fr/tel-00721940.
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La planification de traitement en radiothérapie nécessite un calcul précis de la dose délivrée au patient. La méthode la plus fiable pour y parvenir est la simulation du transport des particules par technique Monte Carlo. Cette thèse constitue la première étude concernant la validation de la plateforme de simulation Monte Carlo GATE (GEANT4 Application for Tomographic Emission), basée sur les librairies de GEANT4 (GEometry ANd Tracking), pour le calcul de la dose absorbée déposée par des faisceaux d'électrons. L'objectif de cette thèse est de montrer que GATE/GEANT4 est capable d'atteindre le niveau d'exigences requis pour le calcul de la dose absorbée lors d'une planification de traitement, dans des situations où les algorithmes analytiques, actuellement utilisés dans les services de radiothérapie, n'atteignent pas un niveau de précision satisfaisant. L'enjeu est de prouver que GATE/GEANT4 est adapté pour la planification de traitement utilisant des électrons et capable de rivaliser avec d'autres codes Monte Carlo reconnus. Cet enjeu a été démontré par la simulation avec GATE/GEANT4 de faisceaux et des sources d'électrons réalistes utilisées en radiothérapie externe ou en radiothérapie moléculaire et la production de distributions de dose absorbée en accord avec les mesures expérimentales et avec d'autres codes Monte Carlo de référence pour la physique médicale. Par ailleurs, des recommandations quant à l'utilisation des paramètres de simulation à fixer, assurant un calcul de la distribution de dose absorbée satisfaisant les spécifications en radiothérapie, sont proposées.
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Leuthold, Jan. "Untersuchungen zur Qualität von peripheren Blutstammzellpräparaten." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2003. http://dx.doi.org/10.18452/14908.
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Das moderne Therapiekonzept der Hochdosischemotherapie von soliden Tumoren und hämatologischen Neoplasien erfordert die prätherapeutische Sammlung, die extrakorporale Reinigung und die nachfolgende Tieftemperaturlagerung von menschlichen Blutstammzellen zur späteren Retransplantation. Stammzellpräparate (Transplantate) von 22 Patienten wurden durch extrakorporale Trennung von peripheren Blut hergestellt. Von jedem Patienten wurde eine Probe mit Dimethylsulfoxid (DMSO) versetzt, bei - 196 oC gelagert und nach ca. 3 Wochen aufgetaut. Eine Vergleichsprobe jedes Patienten wurde ohne den Zusatz von DMSO und ohne einen Einfrierschritt untersucht. Die Exposition von DMSO, das Frieren und Auftauen der Zellen zeigte eine geringfügige des Zell- und Kerndurchmessers, eine konstante Anzahl an Mitochondrien und eine Reduktion der Vesikel. Ein markantes Merkmal der Schädigung nach Tieftemperaturlagerung war das Auftreten von Flüssigkeitseinlagerungen in die Kerndoppelmembran und die Ausbildung von zisternenartigen Erweiterungen des endoplasmatischen Retikulums. Regelmäßig konnten Mitochondrien von verringerter Größe und randständig kondensierter Cristae gefunden werden. Insgesamt konnten keine schwerwiegenden zellulären Schäden beim Vergleich der unbehandelten und der DMSO- versetzten , eingefrorenen und wieder aufgetauten Proben festgestellt werden. Die morphologischen Ergebnisse korrespondieren mit der vollständigen Restitution aller hämatopoetischer Zelllinien nach Transplantation.The modern therapeutic concept of high-dose chemotherapy of solid tumors and hematologic neoplasias demands a pretherapeutic harvest, an extracorporal purification and an consecutive deep temperature storage of human blood stem cells which will be retransplanted later. Stem cell preparates (transplants) of 22 patients were produced by extracorporal separation of peripheral blood. From each patient a stem cell specimen was mixed with dimethylsulfoxide (DMSO), storaged at - 196 °C and thawed after about 21 days. A corresponding specimen of each patients material was investigated without DMSO addition and without freezing under native conditions. The DMSO exposed, frozed and again defrosted cells showed a mild increase of total cell and nucleus diameters, a constant number of mitochondrias and a reduction of vesicles. A markedly feature of deep temperature damage was the occurance of liquide storages in the nucleus double membrane and the forming of cisterne-like enlargement of the endoplasmatic reticulum. Persistantly we found mitochondrias with reduced size and marginal condensed cristae. Alltogether there were no severe cellular damages in the comparative investigated overlifed specimen cells of the same patient with and without DMSO and deep temperature storage. The morphological results correspond with clinical investigations of a sufficient restitution of all hematopoietic cell lineages in transplanted patients.
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Hanna, Rachelle. "Transport de charges et mécanismes de relaxation dans les matériaux diélectriques à usage spatial." Thesis, Toulouse, ISAE, 2012. http://www.theses.fr/2012ESAE0026.
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Comprendre et modéliser le comportement des matériaux sous irradiation électronique est un enjeu important pour l’industrie spatiale. La fiabilité des satellites nécessite de maîtriser et prédire les potentiels de surface s'établissant sur les diélectriques. Ce travail de doctorat a donc pour objectif de caractériser et de modéliser les différents mécanismes physiques (en surface et en volume) gouvernant le potentiel de charges dans les matériaux polymères spatiaux tels que le Téflon® FEP et le Kapton® HN. La mise au point d'un nouveau dispositif et d'un protocole expérimental a permis de corroborer l'existence d’une conductivité latérale des charges, souvent négligée dans les modèles physiques et numériques. Les études paramétriques, révélant l’influence de l’énergie et le flux des électrons incidents, ont permis de brosser un portrait des processus mis en jeu pour le transport (par saut ou par piégeage/dépiégeage) de charges en surface. A la lumière de cette étude, une conductivité équivalente est extraite, assimilant le matériau à un système prenant en compte les mécanismes de transport volumique et surfacique. L'analyse des évolutions non-monotones de potentiel mesurées sur les polymères spatiaux en condition spatiale a permis de révéler une dépendance de la conductivité volumique induite sous irradiation avec la dose reçue. L'étude paramétrique réalisée sur les mécanismes de transport en volume révèle une influence minoritaire du déplacement du barycentre de charges et du vieillissement physicochimique. Un modèle «0D» à un seul niveau de pièges, prenant en compte les mécanismes de piégeage/dépiégeage et recombinaison entre les porteurs de charges, a été développé. Ce modèle simplifié permet de reproduire qualitativement les évolutions de potentiel expérimentales en fonction du débit de dose et lors d'irradiations successivesCharging behaviours of space dielectric materials, under electron beam irradiation, is of special interest for future spacecraft needs, since this mechanism could induce electrostatic discharges and consequently damages on the sensitive systems on board. In order to assess the risks of charging and discharging, this work aims at understanding the overall charge transport mechanisms and predicting the electrical behaviour of the insulator materials, especially Teflon® FEP and Kapton® HN. For an optimized prediction, the first part of our work is thus to check whether lateral conduction process can take place in the overall charge transport mechanism. Through the definition of a new experimental set-up and protocol, we have been able to discriminate between lateral and bulk conductivity and to reveal the presence of lateral conductivity that is enhanced by radiation ionization processes. We have been able to demonstrate as well that lateral intrinsic conductivity is enhanced with the increase current density and when approaching the sample surface. The second part of our work deals with the characterization of the electrical charging behaviour of Teflon® FEP under multi-energetic electron beam irradiation and the modelling of the overall bulk charge transport mechanisms. An experimental study on charge potential evolution as a function of electron spectrum, electric field, relaxation time, dose and dose rate, was performed. A numerical model has been developed to describe the effect of the different abovementioned mechanisms on the evolution of the surface potential. This model agrees correctly with the experimental phenomenology at qualitative level and therefore allows understanding the physical mechanisms steering charge transport in Teflon® and Kapton®
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Lemaire, Matthieu. "Validation des calculs d'échauffements photoniques en réacteur d'irradiation au moyen du programme expérimental AMMON et du dispositif CARMEN." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4072/document.
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Le Réacteur Jules Horowitz (RJH) est un réacteur d’irradiation technologique actuellement en construction au CEA Cadarache. Ce réacteur permettra de réaliser les études scientifiques sur le comportement des matériaux et des combustibles sous irradiation.Pour répondre aux enjeux du RJH, il est nécessaire de valider les outils de calcul des échauffements photoniques (les codes de calcul et la librairie européenne JEFF3.1.1 de données nucléaires) pour le cas spécifique du RJH. Cette problématique est traitée en 3 volets dans cette thèse.Le 1er volet a consisté à quantifier le biais de calcul dû aux données nucléaires de la librairie européenne JEFF3.1.1 pour les calculs d’échauffements photoniques dans le RJH. Ce travail repose sur l’interprétation, avec le code TRIPOLI-4, de mesures d’échauffements réalisées dans la maquette critique EOLE du CEA Cadarache.Le 2ème volet a consisté à obtenir des éléments sur les biais de calcul des échauffements photoniques dus aux méthodes de calcul elles-mêmes. La comparaison calcul / calcul entre différents codes Monte Carlo met en évidence l’importance du transport des particules chargées pour les calculs d’échauffements.Le 3ème volet de ce travail a consisté à fournir des points de comparaison calcul / mesure pour des mesures d’échauffements réalisées dans le réacteur OSIRIS avec une première version du dispositif CARMEN. Le dispositif CARMEN est un projet de dispositif de mesure multi-détecteur innovant pour le RJH. En conclusion, cette thèse a apporté des éléments de validation des calculs d’échauffements photoniques pour le RJH. Ces éléments ont d’ores et déjà été capitalisés pour les études de sûreté du RJHThe Jules Horowitz Reactor (JHR) is the next MTR under construction at CEA Cadarache research center. The JHR will be a major research infrastructure for the test of structural material and fuel behavior under irradiation.To be up to the challenges set by the JHR, It is necessary to validate photon-heating calculation tools (calculation codes and the European nuclear-data JEFF3.1.1 library) for specific use in the JHR. This topic is handled with a three-prong work plan. The first part consisted in quantifying the calculation bias due to the JEFF3.1.1 nuclear-data library on JHR photon-heating calculations. This work relies on the interpretation, with the TRIPOLI-4 code, of heating measurements carried out in the EOLE critical mock-up at CEA Cadarache.The second part of this work is dedicated to the determination of photon-heating calculation biases linked to the approximations of calculation schemes. The calculation / calculation comparison between different Monte Carlo codes highlights the importance of charged-particle transport for heating calculations.The third part of this work consisted in providing calculation / measurement comparisons for heating measurements carried out in the OSIRIS reactor with a prototype of the CARMEN device. The CARMEN device aims at measuring neutron flux, photon flux and nuclear heating simultaneously in the different experimental locations of JHR. In conclusion, this work brings forth validation elements for JHR photon-heating calculations. These elements are already taken into account for the estimation of biases and uncertainties associated with photon-heating calculations for JHR performance and safety studies
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Martin, Luc. "Méthodes de corrections avancées des effets de proximité en lithographie électronique à écriture directe : Application aux technologies sub-32nm." Thesis, Lyon, INSA, 2011. http://www.theses.fr/2011ISAL0003.
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Pour adresser les nœuds technologiques avancés dans le cadre de la lithographie électronique, une nouvelle stratégie de correction des effets de proximité a été imaginée pour prendre le relai de la technique standard de modulation de dose. Dans ces travaux de thèse, les effets de proximité ont été analysés sur les outils e-beam de dernière génération au sein du LETI. Les limites de la modulation de dose ont aussi été évaluées. Parallèlement, une approche plus fondamentale, basée sur la simulation, a permis de mieux comprendre l'impact des différentes étapes du procédé de lithographie sur les motifs réalisés. Une nouvelle stratégie de correction avancée, appelée exposition multiple, a ensuite été mise au point. Celle-ci fait intervenir des motifs spécifiques appelés eRIF (electron Resolution lmprovement Features) dont l'exposition, couplée à celle des motifs initiaux permet de mieux contrôler la répartition de la dose injectée dans la résine. On parle alors d'expositions multiples. Au cours de ces travaux le positionnement des eRIF, ainsi que leurs dimensions ont fait l'objet d'une étude approfondie. L'élaboration d'algorithmes d'optimisation et la réalisation d'expérimentations en salle blanche ont permis d'optimiser ces paramètres et de mettre en évidence les gains apportés par les eRIF. Par rapport à la modulation de dose, des améliorations significatives ont pu être démontrées sur de véritables circuits intégrés. Grâce à l'exposition multiple, la résolution ultime des outils de lithographie e-beam a été repoussée de 2 nœuds technologiques pour les niveaux les plus critiques d'un circuit. Les règles de dessin retenues pour réaliser les eRIF ont ensuite été intégrées dans des modèles de corrections. via le logiciel de préparation de données INSCALE d'ASELTA NANOGRAPHICS pour assurer une correction automatisée des circuitsIn electron beam lithography, a new proximity affects correction strategy has been imagined to push the resolution capabilities beyond the limitations of the standard dose modulation. In this work, the proximity affects inherent to e-beam lithography have been studied on the newest e-beam tools available at LETI. First, the limits of the standard dose modulation correction have been evaluated. The influences of each step of the lithographic process have also been analyzed from a theoretical point a view. A simulation approach was built and used to determine the impact of each of these steps on the patterned features. Then, a new writing strategy has been fully developed. It involves sub resolution features known as eRIF (electron Resolution Improvement features) which provide a finer control of the dose profile into the resist. Since the eRIF are exposed a top the nominal features, this new writing strategy is called multiple pass exposure. In this work, the position, the dose and the design of the eRIF have been studied and optimized to get the best of this new strategy. To do so, experiments were led in a clean room environment, and minimization algorithms have been developed. It has been demonstrated that the eRIF provide a significant gain compared to the standard dose modulation. Improvements have been observed even on the most critical levels of the Integrated circuits. By using the multiple pass exposure with optimized eRIF, the resolution capabilities of the e-beam tool have been reduced by 2 technological nodes. The design rules that have been determined to use the eRIF the most efficient way were finally implemented in INSCALE, the new data preparation software developed by ASELTA NANOGRAPHICS. This way, multiple pass exposure can be used in an automated mode to correct full layouts
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OLIVEIRA, ICIMONE B. de. "Desenvolvimento do cristal semicondutor de brometo de tálio para aplicações como detector de radiação e fotodetector." reponame:Repositório Institucional do IPEN, 2006. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11385.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:01/09049-5