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. Dans-cette-travail-de-thèse, nous avons développé une méthode de correction du diffusé flexible et adaptablè a de nombreux cas rencontrés en tomographie industrielle, pp.100-106

. Mev, La méthode développée s'applique sur les projections, elle est donc indépendante de l'algorithme de reconstruction utilisée ensuite. La méthode nécessite de simuler que quelques cas

. Le-modèle-basé-sur-la-carte, Dans lapremì ere approche, nous avons adopté la méthode simple de calcul d'´ epaisseur en utilisant la loi de Beer-Lambert. Pour tenir compte davantage de l'effet de durcissement du faisceau de l'´ epaisseur a ´ eté calculée sur la base des tables de consultation. Cependant, cette approche estégalementestégalement limitée sur la modélisation du spectre du logiciel simulant. Une des méthodes de calcul de l'´ epaisseur au niveau de chaque pixel peut se faire par l'utilisation de la méthode de lancer de rayon

. Mev, ´ energie les processusélectroniquesprocessusélectroniques comme le rayonnement de freinage deviennent non négligeable. CIVA ne tenant pas compte de ces processus, il faudra simuler les noyaux avec des codes plus complet comme MCNP ou Penelope

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. Ecole-doctorale:-Électronique, A. Électrotechnique, and . Spécialité, La nature des matériaux et les épaisseurs traversées conduisent inévitablement à la génération de rayonnement diffusé Ce dernier est généré par l'objet mais également par le détecteur. La présence de rayonnement parasite conduit à ne plus respecter l'hypothèse de la loi de Beer-Lambert. Par conséquent, on voit apparaitre sur les coupes tomographiques des artefacts de reconstruction comme des streaks, des effets ventouses ou des valeurs d'atténuation linéaire erronée. Par conséquence, on retrouve dans la littérature de nombreuses méthodes de correction du diffusé. Ce travail vise à mettre en point et tester une méthode originale de correction du diffusé. Le premier chapitre de cette étude, dresse un état de l'art de la plupart des méthodes de corrections existantes. Nous proposons, dans le deuxième chapitre, une évolution de la méthode de superposition des noyaux de convolution (Scatter Kernel Superposition) Notre méthode repose sur une description continue des noyaux en fonction de l'épaisseur traversée. Dans cette méthode, les noyaux de diffusion sont paramétrés analytiquement sur toute la plage d'épaisseur. Le procédé a été testé pour des objets à la fois mono-matériaux et poly-matériaux, ainsi que sur des données expérimentales et simulées. Nous montrons dans le troisième chapitre l'importance de la contribution du diffusé détecteur dans la qualité de l'image reconstruite. Mais également l'importance de décrire les noyaux de convolution à l'aide d'un modèle à quatre gaussienne

C. Département-d-sijbers and I. Lyon, Imagerie et de Simulation pour le Contrôle (DISC) Centre de Recherche en Acquisition et Traitement de l'Image pour la Santé (CREATIS) Directeur de thèse: Jean Michel Létang Président de jury : Composition du jury Alessandro Olivo et Dimitris Visvikis Cette thèse est accessible à l'adresse : http://theses.insa-lyon