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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
571

Positron Emission Tomography for Pre-Clinical Sub-Volume Dose Escalation

Bass, Christopher 23 August 2013 (has links)
Purpose: This dissertation focuses on establishment of pre-clinical methods facilitating the use of PET imaging for selective sub-volume dose escalation. Specifically the problems addressed are 1.) The difficulties associated with comparing multiple PET images, 2.) The need for further validation of novel PET tracers before their implementation in dose escalation schema and 3.) The lack of concrete pre-clinical data supporting the use of PET images for guidance of selective sub-volume dose escalations. Methods and materials: In order to compare multiple PET images the confounding effects of mispositioning and anatomical change between imaging sessions needed to be alleviated. To mitigate the effects of these sources of error, deformable image registration was employed. A deformable registration algorithm was selected and the registration error was evaluated via the introduction of external fiducials to the tumor. Once a method for image registration was established, a procedure for validating the use of novel PET tracers with FDG was developed. Nude mice were used to perform in-vivo comparisons of the spatial distributions of two PET tracers, FDG and FLT. The spatial distributions were also compared across two separate tumor lines to determine the effects of tumor morphology on spatial distribution. Finally, the research establishes a method for acquiring pre-clinical data supporting the use of PET for image-guidance in selective dose escalation. Nude mice were imaged using only FDG PET/CT and the resulting images were used to plan PET-guided dose escalations to a 5 mm sub-volume within the tumor that contained the highest PET tracer uptake. These plans were then delivered using the Small Animal Radiation Research Platform (SARRP) and the efficacy of the PET-guided plans was observed. Results and Conclusions: The analysis of deformable registration algorithms revealed that the BRAINSFit B-spline deformable registration algorithm available in SLICER3D was capable of registering small animal PET/CT data sets in less than 5 minutes with an average registration error of .3 mm. The methods used in chapter 3 allowed for the comparison of the spatial distributions of multiple PET tracers imaged at different times. A comparison of FDG and FLT showed that both are positively correlated but that tumor morphology does significantly affect the correlation between the two tracers. An overlap analysis of the high intensity PET regions of FDG and FLT showed that FLT offers additional spatial information to that seen with FDG. In chapter 4 the SARRP allowed for the delivery of planned PET-guided selective dose escalations to a pre-clinical tumor model. This will facilitate future research validating the use of PET for clinical selective dose escalation.
572

An Investigation of NURBS-Based Deformable Image Registration

Jacobson, Travis J 01 January 2014 (has links)
Deformable image registration (DIR) is an essential tool in medical image processing. It provides a means to combine image datasets, allowing for intra-subject, inter-subject, multi-modality, and multi-instance analysis, as well as motion detection and compensation. One of the most popular DIR algorithms models the displacement vector field (DVF) as B-splines, a sum of piecewise polynomials with coefficients that enable local shape control. B-splines have many advantageous properties in the context of DIR, but they often struggle to adequately model steep local gradients and discontinuities. This dissertation addresses that limitation by proposing the replacement of conventional B-splines with a generalized formulation known as a Non-Uniform Rational B-Splines (NURBS). Beginning with the 1D fitting, heuristic rules are developed to determine the values of the additional free parameters introduced by NURBS. These rules are subsequently modified and extended to the 2D and 3D fitting of anonymized and publicly available patient DVFs. Based on the lessons learned from these increasingly complex test cases, a 2D DIR scheme is developed and tested on slices from a thoracic computed tomography (CT) scan. Finally, an automatic, non-uniform scheme is presented, and its registration performance is compared to the conventional uniform methods.
573

Cryptographie visuelle pour l’authentification de documents / Visual cryptography for documents authentification

Machizaud, Jacques 27 September 2012 (has links)
La cryptographie visuelle consiste à partager entre plusieurs « Shadow Images » (SIs) un secret qui ne se révèlera à l'oeil de l'observateur qu'à leur superposition. Depuis les travaux de Naor et Shamir, ce procédé cryptographique a été étendu à Des schémas numériques variés, adaptés à diverses problématiques. En revanche, les travaux concernant son implémentation physique sont peu nombreux à ce jour. Cette thèse est consacrée à l'implémentation de la cryptographie visuelle sur des SIs imprimés en demi-tons en vue de l'authentification de documents. Le SI associé au document peut être imprimé sur support opaque ou transparent, les autres SIs étant imprimés sur films transparents. Nous avons résolu la difficulté de leur superposition par une méthode de Fourier permettant le recalage de la structure quasi-périodique d'un SI. La précision de cette méthode nous a permis de développer un système optique de superposition par projection. On verra que les phénomènes physiques responsables du rendu visuel de SIs superposés sont propices à une protection contre la copie illicite du SI associé à un document. La complexité de ces phénomènes et leur dépendance au type d'impression imposent une modélisation physique pour obtenir un rendu précis. Cette approche nous a conduit à considérer la problématique de la reproduction des couleurs et à développer des modèles spectraux adaptés à la superposition de supports imprimés non diffusants et/ou diffusants, en réflexion et en transmission. La précision de ces modèles prédictifs est tout à fait satisfaisante au regard de celle habituellement obtenue dans le domaine de la reproduction des couleurs. Cela nous a permis d'introduire une approche originale de la cryptographie visuelle par ajustement de couleur (color matching) : une même couleur, à une tolérance près basée sur la vision humaine, est générée par différents demi-tons imprimés sur les supports à superposer. La couleur du message peut ainsi constituer un secret partagé entre les SIs de la même façon que l'est le contenu du message. Chaque SI pris individuellement ne laisse fuir aucune information sur la couleur du message, qui ne sera révélée qu'à leur superposition. Cela peut permettre de prévenir une attaque par falsification du SI associé au document (cheating attack ). De plus, le rendu des couleurs étant très dépendant du système d'impression utilisé, une reproduction fidèle à partir d'un système d'impression différent est difficile. La difficulté peut être encore accrue par l'utilisation de caractéristiques d'impression non standard / In this thesis, we will focus on the physical implementation of visual cryptography, which consists in sharing a secret message between several unmeaning images, so-called shadow images, at least one of them being printed. By the principle of the method, no information leaks about the message until the images are properly stacked together. As the alignment of the shadow images hampers the deployment of the visual cryptography in practice, we develop a dedicated image registration method. In contrast with existing methods, ours is not intrusive. We make use of the particular shape of the elementary constituents of the shadow images, the shares, to extract in the Fourier domain the main parameters of the geometrical transformations occurring between the superposed images. We prove that this method allows subpixel accuracy in shadow images registration. We benefit from such ability by implementing visual cryptography in an image projection configuration : the digital shadow image is projected onto the printed one. In this way, the registration is performed automatically by using a digital camera (the resulting superposition being observable by the eye). For the purpose of authentication, one has to deal with specific attacks: the shadow image attached to a given document could be tampered with or copied. In order to prevent such attacks, we have increased the di_culty to reproduce the shadow image by considering color. This approach requires a complete management of colors. Thanks to recent advances in color reproduction, we are able to predict the reflectance and transmittance spectra of supports printed in color. In this thesis, we develop new spectral prediction models namely for piles of printed transparencies as well as for transparencies stacked onto papers, all printed in color. Thus, we are able to predict the color of each share in a shadow image to be printed and to achieve color matching i.e. we are able to reach a color by various combinations of superposed colors. Such a prediction allowed us to introduce a new approach in visual cryptography: color matching when revealing the secret message to be shared into two (or more) shadow images, in order to authenticate the shadow images provider. As the prediction models are sensitive to the calibration of the printing system (printer, inks, supports, halftoning and geometry measurement conditions), the use of special materials will increase the di_culty to generate visually acceptable fake pairs of shadow images
574

Zpřesnění DMR v pískovcovém skalním terénu s využitím přesné registrace dat leteckého laserového skenování / Enhancement of DTM in Sandstone Landscapes Using Precise Registration of Airborne Laserscanning Data

Holman, Lukáš January 2013 (has links)
DTM Improvement in Sandstone Cliffs Relief using precise Co-registration of Airborne Laser Scanning Data Abstract The topic of this thesis is to design innovation of methodology improvement of digital terrain models from airborne laser scanning data in sandstone rocks rugged relief. Theoretical part of this thesis presents the Project GeNeSiS and New Elevation Model Project of the Czech Republic Territory, in which the test datasets were acquired. Simultaneously this section describes in detail methods of co-registrations datasets from strip adjustment to 3D least squares matching method, which have been published until now. In practical part of the work the Pravčická brána model region is introduced firstly. The focus of this section lays on description of new methodology for co-registration and classification of point clouds using spatial query. Co-registration of point clouds, respective detection transform parameters in this thesis is solved by introducing ground control areas. For each such region displacement and rotations in each axis are detected which subsequently determines the global transformation key. Innovation of the thesis lies in the fact that for DTM improvement there is sufficient only one point cloud. The second (and possibly others) point cloud is classified by presented algorithm...
575

Conception de métaheuristiques pour l'optimisation dynamique : application à l'analyse de séquences d'images IRM / Design of metaheuristics for dynamic optimization : application to the analysis of MRI image sequences

Lepagnot, Julien 01 December 2011 (has links)
Dans la pratique, beaucoup de problèmes d'optimisation sont dynamiques : leur fonction objectif (ou fonction de coût) évolue au cours du temps. L'approche principalement adoptée dans la littérature consiste à adapter des algorithmes d'optimisation statique à l'optimisation dynamique, en compensant leurs défauts intrinsèques. Plutôt que d'emprunter cette voie, déjà largement explorée, l'objectif principal de cette thèse est d'élaborer un algorithme entièrement pensé pour l'optimisation dynamique. La première partie de cette thèse est ainsi consacrée à la mise au point d'un algorithme, qui doit non seulement se démarquer des algorithmes concurrents par son originalité, mais également être plus performant. Dans ce contexte, il s'agit de développer une métaheuristique d'optimisation dynamique. Deux algorithmes à base d'agents, MADO (MultiAgent algorithm for Dynamic Optimization) et MLSDO (Multiple Local Search algorithm for Dynamic Optimization), sont proposés et validés sur les deux principaux jeux de tests existant dans la littérature en optimisation dynamique : MPB (Moving Peaks Benchmark) et GDBG (Generalized Dynamic Benchmark Generator). Les résultats obtenus sur ces jeux de tests montrent l'efficacité des stratégies mises en oeuvre par ces algorithmes, en particulier : MLSDO est classé premier sur sept algorithmes évalués sur GDBG, et deuxième sur seize algorithmes évalués sur MPB. Ensuite, ces algorithmes sont appliqués à des problèmes pratiques en traitement de séquences d'images médicales (segmentation et recalage de séquences ciné-IRM cérébrales). A notre connaissance, ce travail est innovant, en ce sens que l'approche de l'optimisation dynamique n'avait jamais été explorée pour ces problèmes. Les gains de performance obtenus montrent l'intérêt d'utiliser les algorithmes d'optimisation dynamique proposés pour ce type d'applications / Many real-world problems are dynamic, i.e. their objective function (or cost function) changes over time. The main approach used in the literature is to adapt static optimization algorithms to dynamic optimization, compensating for their intrinsic defects. Rather than adopting this approach, already widely investigated, the main goal of this thesis is to develop an algorithm completely designed for dynamic optimization. The first part of this thesis is then devoted to the design of an algorithm, that should not only stand out from competing algorithms for its originality, but also perform better. In this context, our goal is to develop a dynamic optimization metaheuristic. Two agent-based algorithms, MADO (MultiAgent algorithm for Dynamic Optimization) and MLSDO (Multiple Local Search algorithm for Dynamic Optimization), are proposed and validated using the two main benchmarks available in dynamic environments : MPB (Moving Peaks Benchmark) and GDBG (Generalized Dynamic Benchmark Generator). The benchmark results obtained show the efficiency of the proposed algorithms, particularly : MLSDO is ranked at the first place among seven algorithms tested using GDBG, and at the second place among sixteen algorithms tested using MPB. Then, these algorithms are applied to real-world problems in medical image sequence processing (segmentation and registration of brain cine-MRI sequences). To our knowledge, this work is innovative in that the dynamic optimization approach had never been investigated for these problems. The performance gains obtained show the relevance of using the proposed dynamic optimization algorithms for this kind of applications
576

Automatic 3D facial modelling with deformable models

Xiang, Guofu January 2012 (has links)
Facial modelling and animation has been an active research subject in computer graphics since the 1970s. Due to extremely complex biomechanical structures of human faces and people’s visual familiarity with human faces, modelling and animating realistic human faces is still one of greatest challenges in computer graphics. Since we are so familiar with human faces and very sensitive to unnatural subtle changes in human faces, it usually requires a tremendous amount of artistry and manual work to create a convincing facial model and animation. There is a clear need of developing automatic techniques for facial modelling in order to reduce manual labouring. In order to obtain a realistic facial model of an individual, it is now common to make use of 3D scanners to capture range scans from the individual and then fit a template to the range scans. However, most existing template-fitting methods require manually selected landmarks to warp the template to the range scans. It would be tedious to select landmarks by hand over a large set of range scans. Another way to reduce repeated work is synthesis by reusing existing data. One example is expression cloning, which copies facial expression from one face to another instead of creating them from scratch. This aim of this study is to develop a fully automatic framework for template-based facial modelling, facial expression transferring and facial expression tracking from range scans. In this thesis, the author developed an extension of the iterative closest points (ICP) algorithm, which is able to match a template with range scans in different scales, and a deformable model, which can be used to recover the shapes of range scans and to establish correspondences between facial models. With the registration method and the deformable model, the author proposed a fully automatic approach to reconstructing facial models and textures from range scans without re-quiring any manual interventions. In order to reuse existing data for facial modelling, the author formulated and solved the problem of facial expression transferring in the framework of discrete differential geometry. The author also applied his methods to face tracking for 4D range scans. The results demonstrated the robustness of the registration method and the capabilities of the deformable model. A number of possible directions for future work were pointed out.
577

Upphävande av ledningsrätt i vattenområde : Hur hanteras eventuell miljöskada inom Stockholms län

Juric, Marija January 2016 (has links)
I dagens samhälle är vi beroende av elkraft, vatten- och avloppsförsörjning, bredband och andra ledningar som är till stor nytta för människor och infrastruktur. För att säkra rätten att dra fram ledningar för olika ändamål bildas det ofta ledningsrätter. Samhällen förändras över tiden och själva tekniken moderniseras. Befintliga ledningar räcker inte till vilket gör att behov av fler ledningar och ledningsrätter uppstår. Ledningar och anläggningar som tjänat ut sitt ändamål ändras eller upphävs. Frågan uppstår då vad som händer med ledningar och dess anordningar efter det att de tjänat ut sitt ändamål. Hur hanteras eventuell miljöskada?   När det skrivs om bildande, ändring och/eller upphävande av ledningsrätter går tankarna oftast till själva processen samt kring nytta av ändamål och syfte som ledningsrätten uppfyller. Själva miljöaspekten är något som det inte pratas lika mycket om. När ledningar befinner sig på sjöbotten eller blir kvarlämnade efter att de tjänat ut sitt ändamål pågår nedbrytning av materialet som sprids ut i vattnet.   De metoder som har använts i arbetet är: (1) en juridisk studie där rättslägget undersöks och beskrivs; (2) en intervjustudie för att analysera hur Lantmäteriet och Länsstyrelsen ser på problematiken kring ledningar som lämnas kvar i vatten efter att ledningsrätt har upphävts samt en intervjustudie för att analysera i vilket mån är fastighetsägarna och ledningsrättshavarna informerade om själva problematiken kring ledningar som finns kvar i vattnet efter att ledningsrätt har upphävts och vem de anser har ansvar att ta bort ledningar för att återställa miljö i vattenområde; (3) en granskning av förrättningsakter för att analysera om tillräcklig information ges ut till fastighetsägarna och ledningsrättshavarna om vad som kommer att hända med ledningar efter att dessa tjänat ut sitt syfte och att analysera om någon miljöbedömning gjorts avseende miljöpåverkan av ledningar i vattenområde.   Resultatet och slutsatsen av examensarbetet ger svar på frågan om den gällande lagstiftningen tar hänsyn till miljö under iordningsställande av ledningsrätten, vilka brister som råder kring hantering av miljöfrågor och hur dessa brister skulle kunna åtgärdas. / In today's society we are dependent on electricity, water and sewage treatment, broadband and other lines, which are of great benefit to people and infrastructure. In order to secure the right to draw up cables for different purposes are formed often rights. Communities change over time, and the technology itself modernized. Existing utility easements are not sufficient, which means that the need for more cables and rights occurs. Existing pipelines and facilities that served their purpose, amended or repealed. The question arises what happens with the lines and the devices after they served their purpose. How is environmental damage managed?   When written about the establishment, amendment and / or termination of utility easements there is usually suggest of the process itself as well as about the advantage of object and purpose of the utility easement which it meet. The environmental aspect is something that is not talked about as much. When the cables are on the bottom of the lake, or gets left behind after they served their purpose, it starts ongoing degradation of the material out in the water. What happened is – impact on environmental and thereby also people's life quality.   The methods used in the work are: (1) a legal study of legal position examined and described; (2) an interview to analyze how the Swedish mapping, cadastral and land registration authority and the County Board looks at the problem of wiring left in the water after a utility easement has been repealed and an interview study to analyze to what extent are the property owners and proprietor of the utility easement informed about the problem of cables left in the water after the utility easement right has been revoked and who they think has the responsibility to remove the cables to restore the environment in the water area; (3) a review of the ordinance acts to analyze whether sufficient information is given out to the property owners and proprietor of the utility easement about what will happen to the cables after they served their purpose and to analyze whether an environmental assessment has been made regarding the environmental impact of the cables in the water area.   The results and the conclusion of the thesis answers the question whether current legislation including the environment during the preparation of utility easement, identifying gaps about the management of environmental issues and how these gaps could be fixed.
578

Multi-modal registration of T1 brain image and geometric descriptors of white matter tracts / Recalage Multi-modal des image du cerveau T1 et les descripteurs de trajectoires de la matière blanche

Siless, Viviana 08 July 2014 (has links)
Le recalage des images du cerveau vise à réduire la variabilité anatomique entre les differentes sujets, et à créer un espace commun pour l'analyse de groupe. Les approches multi-modales essaient de minimiser les variations de forme du cortex et des structures internes telles que des faisceaux de fibres nerveuses. Ces approches nécessitent une identification préalable de ces structures, ce qui s'avère une tâche difficile en l'absence d'un atlas complet de référence. Nous proposons une extension de l'algorithme de recalage difféomorphe des Démons pour recaler conjointement des images et des faisceaux de fibres. Dans cette thèse, nous analysons différentes représentations des faisceaux de fibres comme une séquence de points, un nuage de points, les courants et les mesures. Différentes distances sont analysées et étudiées dans l'algorithme de recalage. Pour simplifier la représentation de la matière blanche nous utilisons et étendons les algorithmes de classification existants. En étendant le recalage d'images afin d'ajouter des descripteurs de la géométrie des fibres nerveuses, nous espérons améliorer les futures analyses concernant les matières grise et blanche. Nous avons démontré l'efficacité de notre algorithme en recalant conjointement des images anatomiques pondérées en T1 et des faisceaux de fibres. Nous avons comparé nos résultats à des approches concurrentes, l'une multimodale s'appuyant sur l'anisotropie fractionnaire et la pondération T1, l'autre sur les tenseurs de diffusion, et obtenu de meilleures performances à l'aide de notre algorithme. Enfin, nous mettons en évidence sur des études de groupe en IRMf que notre méthodologie et notre implémentation apportent un gain en sensibilité de détection des activations cérébrales. / Brain image registration aims at reducing anatomical variability across subjects to create a common space for group analysis. Multi-modal approaches intend to minimize cortex shape variations along with internal structures, such as fiber bundles. These approaches require prior identification of the structures, which remains a challenging task in the absence of a complete reference atlas. We propose an extension of the Diffeomorphic Demons image registration to jointly register images and fiber bundles. In this thesis we analyze differents representations of the fiber bundles such as ordered points, clouds of points, Currents and Measures. Different distances are analyzed and implemented into the registration algorithm. To simplify white matter representation we also analyze, use and extend existing clustering algorithms. By extending the image registration to include geometric fiber bundles descriptors we hope to improve future analyses regarding both, grey and white matter. We demonstrate the efficacy of our algorithm by registering simultaneously T1 images and fiber bundles and compare results with a multi-modal T1+Fractional Anisotropy (FA) and a tensor-based registration algorithms and obtain superior performance with our approach. We provide preliminary evidence that our implementation improves the sensitivity of activation detection in fMRI group studies.
579

Netradiční označení a ochranné známky / Non-conventional signs and trade marks

Uhrinová, Zuzana January 2018 (has links)
(Eng) The submitted master's thesis discusses non-conventional signs and trade marks, which have grown in significance, especially from the perspective of marketing, traders and law, as was demonstrated by the recent amendments of the European trade mark law. The main aim of this thesis is to identify the particularities of non-conventional signs and obstacles to their registration from the perspective of the selected jurisdictions and consequently, to evaluate the reasons and justifications of the countries' approach. After a historical overview of trade mark functions and the development of law in the studied jurisdictions, the thesis is concerned with outlining the theoretical legal basis of trade mark protection in the European Union, Canada, Australia and the United States of America. The main focus of the thesis lies in the specific effects of the law on the individual types of non-conventional signs and trade marks, with a particular emphasis on the decisions of offices and courts, especially the Court of Justice of the European Union. The analysis includes sounds, scents, shapes and colours, as well as motion marks, holograms, position marks and tactile signs. The main part of the thesis is subdivided into several sections in order to grasp the particularities and singularities of each type...
580

Técnica de reconstrução geométrica da superfície do corpo humano baseada em múltiplos sensores de profundidade para aplicação em teleconferência imersiva. / Geometry reconstruction technique of human body surface based on multiple depth sensors for immersive teleconferencing system.

Lemeszenski, Daniel de Andrade 05 April 2013 (has links)
O interesse no uso de técnicas de aquisição de dados 3D em vídeos interativos e sistemas de videoconferência imersiva aumentou significativamente nos últimos anos. A disponibilidade de sensores de profundidade baseados em luz estruturada no varejo apresenta uma série de novas oportunidades em sistemas de teleconferência, entretenimento e e-learning. No entanto, problemas de oclusão frequentemente ocorrem quando é utilizado um único sensor ou técnicas de reconstrução 2,5D. Outras técnicas de interação e aplicações de teleconferências podem exigir uma reconstrução mais completa do usuário. Uma possível solução para isso implica na utilização de múltiplos dispositivos simultaneamente, o que traz novos desafios relacionados ao processo de calibração de câmaras e a aferição do aumento da superfície capturada quando é adicionado um novo sensor. Neste trabalho é apresentada a proposta VMD (Video-avatar from Multiple Depth maps), uma arquitetura de sistema que trata esses dois problemas. Com a finalidade de validar a viabilidade dessa proposta, três experimentos foram feitos resultando em uma análise qualitativa e quantitativa a fim de encontrar uma configuração adequada de múltiplos sensores de profundidade. / The interest in the use of 3D data acquisition techniques in video based interaction and immersive videoconferencing systems has noticeably increased in recent years. The availability of structured light 3D sensors as off-the-shelf hardware presents a series of new opportunities in teleconferences, entertainment and e-learning. However, occlusion issues often occur when it is used a single sensor or 2,5D reconstruction techniques. Other interaction techniques and teleconferencing applications may require a more complete reconstruction of the user. One possible solution to this involves the use of multiple devices simultaneously, which may bring new challenges related to the calibration process of cameras and measurement of the increase in covered area when it is added a new sensor. In this work we present VMD (Video-avatar from Multiple Depth maps), a system architecture that addresses this two issues. In order to validate the feasibility of this proposal, three experiments were performed resulting in a qualitative and quantitative analysis with the purpose of finding a suitable setup with multiple depth sensors.

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