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Uvod: Število ekspozicij dolgoročno vpliva na zmanjšanje senzibilnosti fluorescentne slikovne plošče za računalniško radiografijo, saj več ekspozicij, pomeni večjo izpostavljenost sevanju. Z merjenjem ekspozicijskega indeksa in produkta med dozo in površino ugotavljamo, koliko ionizirajočega sevanja je doseglo slikovni sprejemnik in pacienta. Če želimo ohraniti primerljiv ekspozicijski indeks med novimi in starimi slikovnimi sprejemniki, moramo ustrezno prilagoditi ekspozicijske pogoje. Namen: Namen diplomskega dela je ugotoviti, kako število ekspozicij dolgoročno vpliva na slikovne fluorescentne plošče za računalniško radiografijo ter med seboj primerjati stare in nove slikovne sprejemnike dveh različnih velikosti pri slikanju medenice. Metode dela: Za izdelavo diplomskega dela smo uporabili deskriptivno metodo pregleda literature in eksperimentalno metodo. Ta je zajemala meritve, s pomočjo katerih smo primerjali stare in nove slikovne sprejemnike ter merili kakšen vpliv ima to na dozo in ekspozicijski indeks. Pridobili smo faktorje spremembe ekspozicijskih pogojev za ohranitev približno enakega ekspozicijskega indeksa med starimi in novimi slikovnimi sprejemniki. Rezultati: V raziskavi smo ugotovili, da je ekspozicijski indeks pri uporabi novih slikovnih sprejemnikov občutno višji, zato moramo ustrezno prilagoditi ekspozicijske pogoje. V kolikor uporabimo na novih slikovnih sprejemnikih ustrezno prilagojene ekspozicijske pogoje, primerljive s starimi slikovnimi sprejemniki, dosežemo občutno zmanjšanje doze za pacienta. Razprava in zaključek: Iz rezultatov je razvidno, da obstajajo med starimi in novimi slikovnimi sprejemniki statistično značilne razlike v dozni obremenjenosti slikovnega sprejemnika in pacienta. Ravno tako ugotovimo, da število opravljenih ekspozicij tekom uporabe močno vpliva na kvaliteto slik. Introduction: The number of exposures performed on an imaging plate has a long term impact on the plate itself and lowers its sensitivity. By measuring the exposure index and the dose area product we can define how much ionizing radiation reaches the imaging plate and the patient. If we want to keep the exposure index between the old and the new plates comparable, we have to adjust the exposure parameters correctly. Purpose: The purpose of the diploma work is to assess how the number of exposures affects imaging plates for computed radiography by comparing old and new imaging plates. Methods: To write the diploma work we used the descriptive method by overviewing relevant literature, and the experimental method. This included gathering measurements, which we used to compare the old and the new imaging plates and define what impact this has on the radiation dose for the imaging plate and the dose for the patient. We adjusted the parameters to keep the exposure index comparable. Results: The research showed that the exposure index is much higher when we use a new imaging plate. That is why we have to adjust the exposure parameters. When the parameters used on the new imaging plates are comparable to the parameters used on the old imaging plates, the patient radiation dose is much lower on the new imaging plates. Discussion and conclusion: The results evidently show statistically defined differences in doses on the plate and for the patient comparing old and new imaging plates. Moreover, we can see that the number of exposures performed on an imaging plate in the time of use, affects the quality of the images.

Uvod: Število ekspozicij dolgoročno vpliva na zmanjšanje senzibilnosti fluorescentne slikovne plošče za računalniško radiografijo, saj več ekspoziciji, pomeni večjo izpostavljenost sevanju. Z merjenjem ekspozicijskega indeksa in produkta med dozo in površino ugotavljamo koliko ionizirajočega sevanja je doseglo slikovni sprejemnik in pacienta. Če želimo ohraniti primerljiv ekspozicijski indeks med novimi in starimi slikovnimi sprejemniki, moramo ustrezno prilagoditi ekspozicijske pogoje. Namen: Namen diplomskega dela je ugotoviti, kako število ekspozicij dolgoročno vpliva na slikovne fluorescentne plošče za računalniško radiografijo ter med seboj primerjati stare in nove slikovne sprejemnike pri slikanju roke in kolka. Metode dela: Za izdelavo diplomskega dela smo uporabili deskriptivno metodo pregleda literature in eksperimentalno metodo. Ta je zajemala meritve, s pomočjo katerih smo primerjali stare in nove slikovne sprejemnike ter merili kakšen vpliv ima to na dozo in ekspozicijski indeks. Pridobili smo faktorje spremembe ekspozicijskih pogojev za ohranitev približno enakega ekspozicijskega indeksa med starimi in novimi slikovnimi sprejemniki pri slikanju roke in kolka. Rezultati: V raziskavi smo ugotovili, da je ekspozicijski indeks pri uporabi novih slikovnih sprejemnikov občutno višji, zato moramo ustrezno prilagoditi ekspozicijske pogoje. V kolikor uporabimo na novih slikovnih sprejemnikih ustrezno prilagojene ekspozicijske pogoje, primerljive s starimi slikovnimi sprejemniki, dosežemo občutno zmanjšanje doze za pacienta. Razprava in zaključek: Iz rezultatov je razvidno, da obstajajo med starimi in novimi slikovnimi sprejemniki statistično značilne razlike v dozni obremenjenosti slikovnega sprejemnika in pacienta. Ravno tako ugotovimo, da število opravljenih ekspozicij tekom uporabe vpliva na kvaliteto slik. Introduction: The number of exposures performed on an imaging plate has a long term impact the plate itself and lowers its sensitivity. By measuring the exposure index and the dose area product we can define how much ionizing radiation reaches the imaging plate and the patient. If we want to keep the exposure index between the old and the new plates comparable, we have to adjust the exposure parameters correctly. Purpose: The purpose of the diploma work is to assess how the number of exposures affects imaging plates for computed radiography done on hand and hip by comparing old and new imaging plates. Methods: To write the diploma work we used the descriptive method by overviewing relevant literature, and the experimental method. This included gathering measurements, which we used to compare the old and the new imaging plates and define what impact this has on the radiation dose for the imaging plate and the dose for the patient. The radiographies were done for the hand and the hip. We adjusted the parameters to keep the exposure index comparable. Results: The research showed that the exposure index is much higher when we use a new imaging plate. That is why we have to adjust the exposure parameters. When the parameters used on the new imaging plates are comparable to the parameters used on the old imaging plates, the patient radiation dose is much lower on the new imaging plates. Discussion and conclusion: The results evidently show statistically defined differences in doses on the plate and for the patient comparing old and new imaging plates. Moreover, we can find out that the number of exposure performed on an imaging plate in the time of use, affects the quality of the images.

In order to protect their detection against the giant electromagnetic pulse generated by the interaction of the PETAL laser with its target, PETAL diagnostics will be equipped with passive detectors. For SESAME and SEPAGE systems, a combination of imaging plate (IP) detectors with high-Z material protection layers will be used to provide additional features such as: 1) Ensuring a response of the detector to be independent of its environment and hence homogeneous over the surface of the diagnostics; 2) Shielding the detectors against high-energy photons from the PETAL target. In this work, calibration experiments of such detectors based on IPs were performed at electron and proton facilities with the goal of covering the energy range of the particle detection at PETAL from 0.1 to 200 MeV. The introduction aims at providing the reader the methods and tools used for this study. The second chapter presents the results of two experiments performed with electrons in the range from 5 to 180 MeV. The third chapter describes an experiment and its results, where protons in the energy range between 80 and 200 MeV were sent onto detectors. The fourth chapter is dedicated to an experiment with protons and ions in the energy range from 1 to 22 MeV proton energy, which aimed at studying our detector responses and testing the demonstrator of the SEPAGE diagnostic. We used the GEANT4 toolkit to analyse our data and compute the detection responses on the whole energy range from 0.1 to 1000 MeV.; Afin de protéger leurs systèmes de détection de l'impulsion électromagnétique géante générée par l'interaction du laser PETAL avec sa cible, les diagnostics de PETAL seront équipés de détecteurs passifs. Pour les ensembles SEPAGE et SESAME, une combinaison d'Imaging Plates (IP) et de couches de protection de matériaux de grand numéro atomique sera utilisée, qui permettra: 1) d'assurer que la réponse des détecteurs sera indépendante de son environnement mécanique proche dans les diagnostics et donc homogène sur toute la détection, 2) de blinder les détecteurs contre les photons de haute énergie produits dans la cible de PETAL. Dans le travail présenté ici, nous avons réalisé des expériences d'étalonnage avec les IPs auprès d'installations générant des électrons, des protons ou des ions, dans le but de couvrir le domaine en énergie cinétique de la détection des particules chargées de PETAL, de 0.1 à 200 MeV. L'introduction a pour but de décrire les méthodes et outils utilisés au cours de cette étude. Le second chapitre présente les résultats de deux expériences réalisées avec des électrons dans le domaine d'énergie cinétique [5-180] MeV. Le troisième chapitre décrit une expérience et ses résultats avec les protons entre 80 et 200 MeV étaient envoyés sur nos détecteurs. Le quatrième chapitre est consacré à une expérience utilisant des protons et des ions entre1 et 22 MeV en énergie de protons et dont l'objectif était l'étude de détecteurs et le test du démonstrateur de SEPAGE. Nous avons utilisé GEANT4 pour l'analyse de nos données et prédire la réponse de nos détecteurs dans le domaine 0.1 à 1000 MeV.

As an image recording medium for transmission positron microscopes, imaging plates are quite useful and powerful. Imaging plates are also quite sensitive and the photon-stimulated luminescence (PSL) is linearly proportional to the positron intensity in six digits (106). No bulky or expensive equipment is necessary to accommodate in vacuum. Imaging plates can be set under bright lights, this is different from the photographic films. Darkness is only required during exposure and transfer to a reader. Slow Positron Facility at KEK, Japan was used to study the effect of “mono-chromatic” positron beam. Specimens were set just in front of an imaging plate. After a certain time of exposure, the imaging plates were processed by a reader. Used imaging plates can be used repeatedly after erased by ultra-violet lights. Images through samples can be obtained. Similar experiments using non-monochromatic (white) positrons and electrons have been performed at Teikyo University of Science and Technology (TUST) and Research Reactor Institute, Kyoto Univ. (RRI). Sealed 22Na positron source can be conveniently used for non-destructive tests.

A personal imaging plate (IP) dosimeter is in the process of being developed for neutron fields using the BaFBr: Eu 2 + phosphor. A configuration incorporating a polyethylene radiator placed before the IP detector is used to produce protons via (n,p) elastic scattering. For a dosimeter sensitive to thermal neutrons, a Nylon plate ( 100 μ m thick) is placed between the polyethylene (1.2 mm thick) radiator and the IP ( 130 μ m thick sensitive layer) detector to produce protons via the 14 N ( n , p ) 14 C reaction. Dosimeters having these configurations have been exposed to neutrons from 241 Am –Be and 252 Cf sources at the Institute for Radioprotection and Nuclear Safety of Cadarache at angles of 0 ∘ (normal incidence), 30 ∘ and 60 ∘ and several dose equivalents. The personal dose equivalent response in terms of H p ( 10 ) is evaluated from the net measured photostimulated luminescence densities ( PSL mm - 2 ). The calibration factor obtained for estimating the personal dose equivalent with this dosimeter is 9.20 × 10 - 5 mSv PSL - 1 mm 2 for 241 Am –Be and 13.07 × 10 - 5 mSv PSL - 1 mm 2 for 252 Cf .

Various forms of industrial radiography have been used for decades in non-destructive inspection. Recent advances in digital image acquisition, either through digitalization of analogue x-ray scans or by direct digital recording of x-rays, as well as improvements in x-ray source designs, have resulted in broadened scope of application, reduced cost, and increased speed of inspection. From system design standpoint, source and detection of radiation are the most important components ; various types of sources and detectors are described in detail, with special care for both advantages and disadvantages of specific types. Recent advances in Computed Tomography are also described, along with its principle of operation and potential for traceable dimensional measurements.

This work takes place in the framework of the characterization and theoptimization of laser-driven electron and photon sources. With the goal of usingthese sources for nuclear physics experiments, we focused on 2 energy ranges:one around a few MeV and the other around a few tens of keV. The first partof this work is thus dedicated to the study of detectors routinely used forthe characterization of laser-driven particle sources: Imaging Plates. A modelhas been developed and is fitted to experimental data. Response functions toelectrons, photons, protons and alpha particles are established for SR, MS andTR Fuji Imaging Plates for energies ranging from a few keV to several MeV. Thesecond part of this work present a study of ultrashort and intense electron andphoton sources produced in the interaction of a laser with a solid or liquid target.An experiment was conducted at the ELFIE facility at LULI where beams ofelectrons and photons were accelerated up to several MeV. Energy and angulardistributions of the electron and photons beams were characterized. The sourceswere optimized by varying the spatial extension of the plasma at both the frontand the back end of the initial target position. In the optimal configuration ofthe laser-plasma coupling, more than 10exponent11 electrons were accelerated. In the caseof liquid target, a photon source was produced at a high repetition rate on anenergy range of tens of keV by the interaction of the AURORE Laser at CELIA(10exponent16 W cm exponent-2) and a melted gallium target. It was shown that both the meanenergy and the photon number can be increased by creating gallium jets at thesurface of the liquid target with a pre-pulse. A physical interpretation supportedby numerical simulations is proposed., Ce travail de thèse expérimental traite de la caractérisation et de l'optimisation de sources d'électrons et de photons (gamme en énergie keV- MeV) produites lors de l'interaction d'un laser à impulsion courte et intense avec une cible à l'état de plasma. La caractérisation en énergie et angulaire de ces sources est un enjeu d'importance, notamment dans la perspective de les utiliser pour des expériences de physiques nucléaires dans les plasmas. Une partie de ce travail est consacrée à l'étude des écrans photostimulables (IPs), détecteurs couramment utilisés pour la mesure des distributions en énergie et angulaire des faisceaux de particules accélérées par laser. Les caractéristiques des écrans de type MS, SR et TR de la marque Fuji ont été étudiés et leurs fonctions de réponse aux électrons, photons, protons et particules alpha sont établies dans une gamme en énergie de quelques kev à plusieurs MeV. Enfin un protocole est proposé pour réaliser des mesures quantitatives avec ces détecteurs dans différentes configurations expérimentales.Dans une seconde partie, une source d'électrons produite avec l'installation ELFIE du LULI dans la gamme en énergie de l'ordre du MeV a été caractérisée et optimisée en faisant varier l’extension spatiale du pré-plasma dans lequel interagi le laser intense. En particulier nous montrons que plus de 1011 électrons de plus de 10 MeV sont accélérés lors de l’interaction laser- plasma pour des conditions particulières d’extension longitudinale du pré-plasma en amont, mais aussi en aval de la cible.Dans une dernière partie, une source de photons produite à haute cadence avec le laser AURORE du CELIA est étudiée dans une gamme en énergie d'une dizaine de keV. L’originalité de la source réside dans la nature de la cible qui est du gallium à l'état liquide. Nous montrons en particulier que l'énergie moyenne et le nombre des photons peuvent être optimisés en créant des jets de gallium à la surface de la cible au moyen d'une pré-impulsion laser. Une interprétation physique du phénomène est proposée s’appuyant sur des simulations numériques.

We describe a dosimeter incorporating BaFBr:Eu2+ imaging plates (IPs) for fast neutron ambient dose equivalent measurements. Its configuration and some of its characteristics will be described. While IPs are far more sensitive to radiation than photographic film or track detectors, they are nevertheless subject to fading and account must be taken of this phenomenon in order to arrive at a correct dose estimation. A procedure for making the fading correction will be presented.