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Thèses sur le sujet « Virtual imaging »
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1
Wang, Lulu. « Virtual imaging system ». Click here to access this resource online, 2009. http://hdl.handle.net/10292/668.
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The main purpose of this research project was to implement a combination of computer graphics and processing to generate displays that will aid in the visualization of the colour rendering properties of a range of light sources, including the new generation of high-output LEDs (light emitting diodes) that are becoming widely adopted in general lighting service. The CIE (International Commission on Illumination) has developed a colour appearance model CIECAM02 for use in colour imaging and colour management, and this model is utilized in this work. This thesis describes the design and construction of a computer-based model that can be used as a research tool for the simulation and demonstration of the colour rendering properties of various artificial light sources. It is a comprehensive study of the colour models and measurement procedures currently in use in the lighting industry, as recommended by the CIE. This research project focused on the display of a set of surface colour patches as if they were illuminated by a specific light source, and the simultaneous display of two such sets to demonstrate the surface colour differences arising from the use of the two different light sources. A VIS (virtual imaging system) has been developed to display the colour properties of a series of test colour samples under different light sources. This thesis describes the computer models developed for the representation and display of surface colours in general, and colour rendering in particular. The designed system computes and displays the colour of each sample from a knowledge of the light-source spectrum and the spectral reflectance of each surface. It can simultaneously display the colours resulting from illumination by two different sources. In addition, the system computes the colour appearance differences for two sets of colours using the CIECAM02 colour appearance model. Subjective and objective tests were taken to validate the computed results. The VIS has been designed and implemented. It also has been tested by 21 observers and we believe that it will be a powerful research tool for the lighting industry, especially in relation to colour rendering.
2
Rose, John Frederick William. « Visually adaptive virtual acoustic imaging ». Thesis, University of Southampton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399992.
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Gledhill, Duke. « 3D panoramic imaging for virtual environment construction ». Thesis, University of Huddersfield, 2009. http://eprints.hud.ac.uk/id/eprint/6981/.
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The project is concerned with the development of algorithms for the creation of photo-realistic 3D virtual environments, overcoming problems in mosaicing, colour and lighting changes, correspondence search speed and correspondence errors due to lack of surface texture. A number of related new algorithms have been investigated for image stitching, content based colour correction and efficient 3D surface reconstruction. All of the investigations were undertaken by using multiple views from normal digital cameras, web cameras and a ”one-shot” panoramic system. In the process of 3D reconstruction a new interest points based mosaicing method, a new interest points based colour correction method, a new hybrid feature and area based correspondence constraint and a new structured light based 3D reconstruction method have been investigated. The major contributions and results can be summarised as follows: • A new interest point based image stitching method has been proposed and investigated. The robustness of interest points has been tested and evaluated. Interest points have been proved robust to changes in lighting, viewpoint, rotation and scale. • A new interest point based method for colour correction has been proposed and investigated. The results of linear and linear plus affine colour transforms have proved more accurate than traditional diagonal transforms in accurately matching colours in panoramic images. • A new structured light based method for correspondence point based 3D reconstruction has been proposed and investigated. The method has been proved to increase the accuracy of the correspondence search for areas with low texture. Correspondence speed has also been increased with a new hybrid feature and area based correspondence search constraint. • Based on the investigation, a software framework has been developed for image based 3D virtual environment construction. The GUI includes abilities for importing images, colour correction, mosaicing, 3D surface reconstruction, texture recovery and visualisation. • 11 research papers have been published.
4
Ren, Jinsong. « Software tools for integral imaging virtual studios ». Thesis, De Montfort University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406029.
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5
Papadopoulos, Timoleon. « Inverse filtering for virtual acoustic imaging systems ». Thesis, University of Southampton, 2006. https://eprints.soton.ac.uk/157421/.
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The research topic of this thesis is the use of inverse filtering for the design and implementation of two-channel virtual acoustic imaging systems that utilise loudspeakers. The basic objective of such systems is to invert the electroacoustic plant between the input to the loudspeakers and the output at the listener’s ears and hence make it possible for a pair of binaural signals to be locally reproduced at the position of the listener’s ears. As a starting point for the research presented, a previously introduced type of inverse filtering design is considered in which the inverse is implemented with FIR filters. The basic formulation of this design is described and a number of innovative points regarding its implementation are made. An experimental procedure is then formulated for the evaluation of the effectiveness of this inverse filtering design that is based on objective measurements of the inversion process. Unlike previously employed methods that are based on computer simulations or subjective experiments, the introduced experimental procedure is shown to be very efficient in isolating and exactly quantifying the effect on the accuracy of the inversion of a number of errors and approximations typically present in the implementation. A detailed evaluation is thus presented of the inverse filtering design at hand in realistic conditions of implementation. Subsequently, a novel method for the off-line implementation of the inverse filtering is presented that utilises recursive filters of lower order. In this method, the responses of the inverse filters are decomposed into two parts, one realisable in forward time and one in backward time. The effectiveness of this new method for the implementation of the inverse is tested and compared with a small selection of the objective evaluation results described above. Finally, an algorithm for the on-line implementation of the forward-backward inverse filtering is proposed and its computational cost is compared with the currently available frequency-domain block-processing filtering algorithms.
6
Mannerheim, P. V. H. « Visually adaptive virtual sound imaging using loudspeakers ». Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/157423/.
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Advances in computer technology and low cost cameras open up new possibilities for three dimensional (3D) sound reproduction. The problem is to update the audio signal processing scheme for a moving listener, so that the listener perceives only the intended virtual sound image. The performance of the audio signal processing scheme is limited by the condition number of the associated inversion problem. The condition number as a function of frequency for different listener positions and rotation is examined using an analytical model. The resulting size of the "operational area" with listener head tracking is illustrated for different geometries of loudspeaker configurations together with related cross-over design techniques. An objective evaluation of cross-talk cancellation effectiveness is presented for different filter lengths and for asymmetric and symmetric listener positions. The benefit of using an adaptive system compared to a static system is also illustrated. The measurement of arguably the most comprehensive KEMAR database of head related transfer functions yet available is presented. A complete database of head related transfer functions measured without the pinna is also presented. This was performed to provide a starting point for future modelling of pinna responses. The update of the audio signal processing scheme is initiated by a visual tracking system that performs head tracking without the need for the listener to wear any sensors. The solution to the problem of updating the filters without any audible change is solved by using either a very fine mesh for the inverse filters or by using commutation techniques. The filter update techniques are evaluated with subjective experiments and have proven to be e®ective both in an anechoic chamber and in a listening room, which supports the implementation of virtual sound imaging systems under realistic conditions. The design and implementation of a visually adaptive virtual sound imaging system is carried out. The system is evaluated with respect to filter update rates and cross-talk cancellation effectiveness.
7
Schuette, Kathrin. « The role of virtual imaging in building conservation ». Thesis, University of Plymouth, 2018. http://hdl.handle.net/10026.1/13076.
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Conservation is the process of managing changes to significant historic buildings and places. This research explores key conservation concepts, identifying internationally agreed conservation principles and their relationship to the developing role of computer-based visualisation in the conservation process. An emphasis is placed upon documentation that plays an important part in conservation and has begun to recognise virtual imaging as a tool for recording, analysing, interpreting and presenting the cultural heritage. This research focuses in particular upon virtual imaging from the perspective of a building conservator. It addresses both the purpose and possibilities of virtual imaging, which are useful in terms of the act of conservation and more specifically regarding documentation, which itself informs and records the work of a conservator. How can virtual imaging support the practice of the building conservation, with particular reference to documentation including recording and interpretation has been explored through considering the stages of the conservation process. To enable this examination a table has been created to address the question "Where, when and for what purpose an image is supportive in conservation" in relation to the conservation process. This has been informed by the Spinal Steps recommended by E.C.C.O. (The European Confederation of Conservator-Restorer's Organisation). In addition, to better understanding the potential of this emerging technology different examples of virtual imaging and their uses have been assessed to help identify the benefits for imaging in VIII building conservation. To further investigate the impact of virtual imaging as a conservator's tool two case studies have been systematically examined to confirm its benefits and which stage of a conservation project they are of optimum use. The overall outcome is that virtual imaging is of particular use to the conservator, and enhances the conservation process and management plan, particularly in terms of documentation and recording historic buildings.
8
GHISLANZONI, L. T. HUANCA. « THREE-DIMENSIONAL DENTAL IMAGING THROUGH VIRTUAL STUDY MODELS ». Doctoral thesis, Università degli Studi di Milano, 2013. http://hdl.handle.net/2434/217618.
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This thesis was conceived as a paper series analyzing the topic of three-dimensional dental imaging through virtual study models. The aim of the thesis was to explore some of the new possibilities of use of three-dimensional virtual study models as a modern diagnostic and research tool. At the time of writing the thesis chapter 2 to 5 have been adapted as papers and submitted to orthodontic journals for approval.
An abstract of each paper is presented here after, while in chapters 2 to 5 the details of each study are described. In chapter 6 general conclusions are presented, while in chapter 7 references for all the papers are reported.
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Tickhill, Justin D. « The virtual pig head digital imaging in cephalic anatomy / ». Ohio : Ohio University, 2007. http://www.ohiolink.edu/etd/view.cgi?ohiou1187634238.
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Takeuchi, Takashi. « Systems for virtual acoustic imaging using the binaural principle ». Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249594.
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Tickhill, Justin David. « The Virtual Pig Head : Digital Imaging in Cephalic Anatomy ». Ohio University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1187634238.
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Galgenmüller, Sabrina [Verfasser]. « Acoustic Radiation Force Imaging der Leber - Generierung von Normwerten und Vergleich der Virtual Touch Tissue Quantification und Virtual Touch Imaging Quantification / Sabrina Galgenmüller ». Ulm : Universität Ulm. Medizinische Fakultät, 2016. http://d-nb.info/1091060924/34.
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Brewin, Michael A. « Reduced information integral imaging ». Thesis, De Montfort University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391420.
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Neuwirt, Christine [Verfasser]. « Acoustic Radiation Force Imaging der Schilddrüse : Generierung von Normwerten mittels Virtual TouchTM Imaging and Quantification / Christine Neuwirt ». Ulm : Universität Ulm, 2017. http://d-nb.info/1129258483/34.
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Geller, Felipe Foletto [UNESP]. « Colonoscopia virtual em cães ». Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/108454.
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000742391.pdf: 851690 bytes, checksum: e154e1e4762d25c0d409a7afaccd3e96 (MD5)Colonoscopia virtual é uma nova modalidade de imagem que permite a reconstrução tridimensional (3D) da superfície endoluminal do cólon, com imagens semelhantes àquelas conseguidas na colonoscopia endoscópica. A técnica é utilizada na detecção de lesões tumorais colorretais de seres humanos. O objetivo do estudo foi de avaliar a viabilidade da colonoscopia virtual em cães e descrever as imagens obtidas. Foram utilizados 10 cães adultos, sem raça definida e que não possuíam sinais clínicos ou histórico de doenças gastrointestinais. Os arquivos DICOM (Comunicação de imagens digital em medicina) gerados pelo tomógrafo foram reconstruídos em imagens de colonoscopia virtual no software Voxar 3D. Nas imagens da colonoscopia virtual nos cães, visibilizou-se a estrutura tubular com vários anéis dispostos ao longo do campo de visão e a parede do cólon lisa e regular. Conclui-se que a colonoscopia virtual pode ser realizada em cães e mostrou-se uma alternativa viável para o diagnóstico das doenças colônicas decorrentes de deslocamentos
Virtual colonoscopy is a new imaging modality that allows reconstruction of three-dimensional (3D) endoluminal surface of the colon, with images similar to those achieved in endoscopic colonoscopy. The technique is used in the detection of colorectal tumors in human beings. The aim of the study was to evaluate the feasibility of virtual colonoscopy in dogs and describe the obtained images. We used 10 adult mongrel dogs, which had no clinical signs or history of gastrointestinal diseases. The DICOM (Digital Imaging and Communications in Medicine) files generated by the CT images were reconstructed in virtual colonoscopy in Voxar 3D software. In the virtual colonoscopy images in dogs the tubular structure with several rings arranged along the field of view could be seen, and the colon wall smooth and regular. We concluded that virtual colonoscopy can be performed in dogs and proved to be a viable alternative for the diagnosis of colonic diseases caused by dislocations
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Geller, Felipe Foletto. « Colonoscopia virtual em cães / ». Botucatu, 2013. http://hdl.handle.net/11449/108454.
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Orientador: Maria Jaqueline MamprimBanca: Cláudia Valéria Suellner
Banca: Maria Lucia Gomes Lourenço
Banca: Ricardo Coelho Lehmkuhl
Banca: Ana Carolina Brandão de Campos Fonseca Pinto
Resumo: Colonoscopia virtual é uma nova modalidade de imagem que permite a reconstrução tridimensional (3D) da superfície endoluminal do cólon, com imagens semelhantes àquelas conseguidas na colonoscopia endoscópica. A técnica é utilizada na detecção de lesões tumorais colorretais de seres humanos. O objetivo do estudo foi de avaliar a viabilidade da colonoscopia virtual em cães e descrever as imagens obtidas. Foram utilizados 10 cães adultos, sem raça definida e que não possuíam sinais clínicos ou histórico de doenças gastrointestinais. Os arquivos DICOM (Comunicação de imagens digital em medicina) gerados pelo tomógrafo foram reconstruídos em imagens de colonoscopia virtual no software Voxar 3D. Nas imagens da colonoscopia virtual nos cães, visibilizou-se a estrutura tubular com vários anéis dispostos ao longo do campo de visão e a parede do cólon lisa e regular. Conclui-se que a colonoscopia virtual pode ser realizada em cães e mostrou-se uma alternativa viável para o diagnóstico das doenças colônicas decorrentes de deslocamentos
Abstract: Virtual colonoscopy is a new imaging modality that allows reconstruction of three-dimensional (3D) endoluminal surface of the colon, with images similar to those achieved in endoscopic colonoscopy. The technique is used in the detection of colorectal tumors in human beings. The aim of the study was to evaluate the feasibility of virtual colonoscopy in dogs and describe the obtained images. We used 10 adult mongrel dogs, which had no clinical signs or history of gastrointestinal diseases. The DICOM (Digital Imaging and Communications in Medicine) files generated by the CT images were reconstructed in virtual colonoscopy in Voxar 3D software. In the virtual colonoscopy images in dogs the tubular structure with several rings arranged along the field of view could be seen, and the colon wall smooth and regular. We concluded that virtual colonoscopy can be performed in dogs and proved to be a viable alternative for the diagnosis of colonic diseases caused by dislocations
Doutor
17
Yang, Mu. « RadPaint a Web-based interactive 3D virtual radiation field application / ». [Gainesville, Fla.] : University of Florida, 2002. http://purl.fcla.edu/fcla/etd/UFE1001198.
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Conroy-Dalton, Ruth Alison. « Spatial navigation in immersive virtual environments ». Thesis, University College London (University of London), 2001. http://discovery.ucl.ac.uk/1111/.
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Morgan, David J. « Algorithmic approaches to finding cover in three-dimensional, virtual environments ». Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03sep%5FMorgan.pdf.
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Thesis (M.S. in Modeling, Virtual Environments and Simulation)--Naval Postgraduate School, September 2003.Thesis advisor(s): Christian J. Darken, Joseph A. Sullivan. Includes bibliographical references (p. 91-92). Also available online.
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Sicuro, David Leonardo Lencastre. « Physically based modeling and simulation of a ship in open water 3-D virtual environment ». Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03sep%5FSicuro.pdf.
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Thesis (M.S. in Electrical Engineering and M.S. in Modeling, Virtual Environments and Simulation)--Naval Postgraduate School, September 2003.Thesis advisor(s): Xiaoping Yun, Fotis Papoulias, Joseph Sullivan. Includes bibliographical references (p. 89-90). Also available online.
21
Wozniak, Peter. « Range imaging based obstacle detection for virtual environment systems and interactive metaphor based signalization ». Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAD013/document.
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Avec cette génération d'appareils, la réalité virtuelle (RV) s'est réellement installée dans les salons des utilisateurs finaux. Ces appareils disposent de 6 degrés de liberté de suivi, ce qui leur permet de se déplacer naturellement dans les mondes virtuels. Cependant, pour une locomotion naturelle dans le virtuel, il faut un espace libre correspondant dans l'environnement réel. L'espace disponible est souvent limité. Les objets de la vie quotidienne peuvent rapidement devenir des obstacles pour les utilisateurs de RV s'ils ne sont pas éliminés. Les systèmes actuellement disponibles n'offrent qu'une aide rudimentaire pour résoudre ce problème. Il n'y a pas de détection d'objets potentiellement dangereux. Cette thèse montre comment les obstacles peuvent être détectés automatiquement avec des caméras d'imagerie à distance et comment les utilisateurs peuvent être avertis efficacement de leur présence dans l'environnement virtuel. 4 métaphores visuelles ont été évaluées à l'aide d'une étude des utilisateursWith this generation of devices, virtual reality (VR) has actually made it into the living rooms of end-users. These devices feature 6 degrees of freedom tracking, allowing them to move naturally in virtual worlds. However, for a natural locomotion in the virtual, one needs a corresponding free space in the real environment. The available space is often limited. Objects of daily life can quickly become obstacles for VR users if they are not cleared away. The currently available systems offer only rudimentary assistance for this problem. There is no detection of potentially dangerous objects. This thesis shows how obstacles can be detected automatically with range imaging cameras and how users can be effectively warned about them in the virtual environment. 4 visual metaphors were evaluated with the help of a user study
22
Stewart, Kyle Bradley. « Waveform-Diverse Multiple-Input Multiple-Output Radar Imaging Measurements ». The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1450437383.
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Miyachi, Shigeru, Takashi Izumi, Noriaki Matsubara, Osamu Hososhima, Yuko Tsurumi et Arihito Tsurumi. « Virtual Histology Analysis of Carotid Atherosclerotic Plaque : Plaque Composition at the Minimum Lumen Site and of the Entire Carotid Plaque ». Wiley-Blackwell, 2013. http://hdl.handle.net/2237/17694.
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Schuster, Tabea Marcia Solveig [Verfasser]. « Quantitative elastographische Beurteilung von Schilddrüsenknoten mit Virtual Touch™ Tissue Imaging Quantification / Tabea Marcia Solveig Schuster ». Ulm : Universität Ulm, 2019. http://d-nb.info/1200022092/34.
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Icenogle, David A. « Development of virtual mitral valve leaflet models from three-dimensional echocardiography ». Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/48994.
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Mitral valve (MV) disease is responsible for approximately 2,581 deaths and 41,000 hospital discharges each year in the US. Mitral regurgitation (MR), retrograde blood from through the MV, is often an indicator of MV disease. Surgical repair of MVs is preferred over replacement, as it is correlated with better patient quality of life. However, replacement rates are still near 40% because MV surgical repair expertise is not spread across all hospitals. In addition, 15-80% of surgical repair patients have recurrent MR within 10 years. Quantitative patient-specific models could aid these issues by providing less experienced surgeons with additional information before surgery and a quantitative map of patient valve changes after surgery. Real-time 3D echocardiography (RT3DE) can provide high quality 3D images of MVs and has been used to generate quantitative models previously. However, there is not currently an efficient, dynamic, and validated method that is fast enough to use in common practice. To fill this need, a tool to generate quantitative 3D models of mitral valve leaflets from RT3DE in an efficient manner was created. Then an in vitro echocardiography correction scheme was devised and a dynamic, in vitro validation of the tool was performed. The tool demonstrated that it could generate dynamic, complex MV geometry accurately and more efficiently than current methods available. In addition, the ability for mesh interpolation techniques to reduce segmentation time was demonstrated. The tool generated by this study provides a method to quickly and accurately generate MV geometry that could be applied to dynamic patient specific geometry to aid surgical decisions and track patient geometry changes after surgery.
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Chen, Pei. « Volumetric reconstruction and real-time deformation modeling of biomedical images ». Access to citation, abstract and download form provided by ProQuest Information and Learning Company ; downloadable PDF file 6.09 Mb., p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3220796.
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Thesis (Ph.D.)--University of Delaware, 2006.Principal faculty advisors: Kenneth E. Barner, Dept. of Electrical and Computer Engineering; and Karl V. Steiner, Delaware Biotechnology Institute. Includes bibliographical references.
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Ziegeler, Sean Bernard. « Using virtual environments to visualize atmospheric data : can it improve a meteorologist's potential to analyze the information ? » Master's thesis, Mississippi State : Mississippi State University, 2002. http://library.msstate.edu/etd/show.asp?etd=etd-04032002-162001.
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Sultana, Razia. « Research on system architecture for device and content independent applications including 3d imaging and virtual reality as content ». Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAD034/document.
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Les réseaux traitant l’information, intègrent différentes technologies incluant une large gamme de dispositifs aux capacités et puissances très variées et capables de gérer une immense quantité d’informations sous forme de données d’une grande diversité de formats. La recherche sur l'imagerie 3D, la réalité virtuelle et autres techniques holographiques permettront d’offrir de nouvelles techniques d’interactions homme/machine (IHM), notamment pour les appareils mobiles. Cela enrichira encore la variété et la diversité de ces dispositifs. Beaucoup d'efforts ont été faits, notamment ces dernières années, afin d’établir une intégration ouverte, évolutive et transparente des différentes technologies permettant l’affichage de contenus, notamment d’images 2D et 3D et ce pour tout type de système, y compris mobile en tenant compte, notamment et de plus en plus, de la situation géographique individuelle de l'utilisateur final. Sur ces différents points, la tâche est loin d’être terminée. Cette thèse représente, dans ce contexte, une contribution, vers la généralisation de la transportabilité des informations pour des objets communicants de natures différentes, notamment portables, particulièrement dans le cas de l’imagerie en 3 dimensions, de plus en plus exploitée.L'objectif de ce travail de recherche est de trouver un moyen de résoudre le problème énoncé ci-dessus en proposant une architecture pour fournir un accès sans contrainte, continu et personnalisé pour le contenu et les applications interactives partout et à tout moment avec la plus grande quantité possible d’appareils communicants. Un exemple d’exploitation utile et particulièrement adaptée d'un tel système est l'apprentissage sur mobile en raison de la grande diversité des appareils communicants disponibles, dotés de caractéristiques et de fonctionnalités très différentes. Comme solution au problème considéré, une nouvelle architecture nommée "Smoothie" est proposée, un prototype a été développé et évalué en tant que composant important d'un jeu d'apprentissage collaboratif de langues étrangères nommé LLG (Language Learning Game)Today’s network landscape consists of many different network technologies, a wide range of end-devices with large scale of capabilities and power, an immense quantity of information and data represented in different formats. Research on 3D imaging, virtual reality and holographic techniques will result in new user interfaces (UI) for mobile devices and will increase their diversity and variety. A lot of effort is being made in order to establish open, scalable and seamless integration of various technologies and content presentation for different devices including those that are mobile, considering the individual situation of the end user. Till today the research is going on in different parts of the world but the task is not completed yet.The goal of this research work was to find a way to solve the above stated problems by investigating system architectures to provide unconstrained, continuous and personalized access to the content and interactive applications everywhere and at anytime with different devices. As a Solution of the problem considered, a new architecture named “Smoothie” is proposed, developed as prototype and evaluated as an important feature of a collaborative foreign language learning game named LLG
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Mao, Dun. « A quality assessment approach and a hole-filling method for DIBR virtual view images ». Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3950633.
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Silva, Fabrício Loreni da. « Adaptação do código Geant4 para conversão de imagens DICOM em phantom virtual ». Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/520.
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CAPESEste trabalho apresenta a adaptação do código Geant4 para conversão de imagens DICOM (Digital Imaging and Communications in Medicine) de crânio, obtidas em tomografia convencional (CT), em um phantom antropomórfico virtual. O trabalho foi baseado no exemplo médico denominado “Código Dicom”, disponibilizado pelos desenvolvedores do código Geant4. Durante a execução do trabalho foram feitas reestruturações no exemplo “Código Dicom” para a conversão direta de imagens tomográficas em um phantom virtual. Foram retirados do código todos os passos referentes aos eventos físicos nucleares. Foi reformulado o arquivo DicomHandler.cc para não realizar a compressão dos pixels da imagem de CT. Em seguida foi realizada a conversão direta de imagens tomográficas, de um phantom físico de polietileno (PEAD) com núcleo central de acrílico e de um crânio real humano, em phantoms virtuais para o código Geant4. Os resultados demonstraram que com este código é possível a reconstrução de áreas anatômicas com geometrias complexas, partindo do uso de imagens tomográficas reais.
This work presents the adaptation of the Geant4 code for converting DICOM (Digital Imaging and Communications in Medicine) images of a skull, obtained in conventional tomography (CT), into a virtual anthropomorphic phantom. The work was based on the medical example named "Dicom Code" provided by the developers of the code Geant4. During the execution, restructurings using the "Dicom Code" example were made to achieve the direct conversion of tomographic images into a virtual phantom. All the steps referring to nuclear physical events were removed. The file DicomHandler.cc was reformulated in order to avoid the pixels compression of the CT image. The CT images of a physical polyethylene (PEAD) phantom with acrylic core and a real human skull were then converted into virtual phantoms for the code Geant4. The results showed that with this code, it may be possible the reconstruction of anatomical areas with complex geometries, based on the use of real tomographic images.
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Shelton, Brett E. « How augmented reality helps students learn dynamic spatial relationships / ». Thesis, Connect to this title online ; UW restricted, 2003. http://hdl.handle.net/1773/7668.
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Chean, Shen Lee. « Numerical study for acoustic micro-imaging of three dimensional microelectronic packages ». Thesis, Liverpool John Moores University, 2014. http://researchonline.ljmu.ac.uk/4502/.
Texte intégralRésumé :
Complex structures and multiple interfaces of modern microelectronic packages complicate the interpretation of acoustic data. This study has four novel contributions. 1) Contributions to the finite element method. 2) Novel approaches to reduce computational cost. 3) New post processing technologies to interpret the simulation data. 4) Formation of theoretical guidance for acoustic image interpretation. The impact of simulation resolution on the numerical dispersion error and the exploration of quadrilateral infinite boundaries make up the first part of this thesis's contributions. The former focuses on establishing the convergence score of varying resolution densities in the time and spatial domain against a very high fidelity numerical solution. The latter evaluates the configuration of quadrilateral infinite boundaries in comparison against traditional circular infinite boundaries and quadrilateral Perfectly Matched Layers. The second part of this study features the modelling of a flip chip with a 140µm solder bump assembly, which is implemented with a 230MHz virtual raster scanning transducer with a spot size of 17µm. The Virtual Transducer was designed to reduce the total numerical elements from hundreds of millions to hundreds of thousands. Thirdly, two techniques are invented to analyze and evaluate simulated acoustic data: 1) The C-Line plot is a 2D max plot of specific gate interfaces that allows quantitative characterization of acoustic phenomena. 2) The Acoustic Propagation Map, contour maps an overall summary of intra sample wave propagation across the time domain in one image. Lastly, combining all the developments. The physical mechanics of edge effects was studied and verified against experimental data. A direct relationship between transducer spot size and edge effect severity was established. At regions with edge effect, the acoustic pulse interfacing with the solder bump edge is scattered mainly along the horizontal axis. The edge effect did not manifest in solder bump models without Under Bump Metallization (UBM). Measurements found acoustic penetration improvements of up to 44% with the removal of (UBM). Other acoustic mechanisms were also discovered and explored. Defect detection mechanism was investigated by modelling crack propagation in the solder bump assembly. Gradual progression of the crack was found have a predictable influence on the edge effect profile. By exploiting this feature, the progress of crack propagation from experimental data can be interpreted by evaluating the C-Scan image.
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Sjölie, Daniel. « Human brains and virtual realities : Computer-generated presence in theory and practice ». Doctoral thesis, Umeå universitet, Institutionen för datavetenskap, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-68664.
Texte intégralRésumé :
A combined view of the human brain and computer-generated virtual realities is motivated by recent developments in cognitive neuroscience and human-computer interaction (HCI). The emergence of new theories of human brain function, together with an increasing use of realistic human-computer interaction, give reason to believe that a better understanding of the relationship between human brains and virtual realities is both possible and valuable. The concept of “presence”, described as the subjective feeling of being in a place that feels real, can serve as a cornerstone concept in the development of such an understanding, as computer-generated presence is tightly related to how human brains work in virtual realities. In this thesis, presence is related both to theoretical discussions rooted in theories of human brain function, and to measurements of brain activity during realistic interaction. The practical implications of such results are further developed by considering potential applications. This includes the development and evaluation of a prototype application, motivated by presented principles. The theoretical conception of presence in this thesis relies on general principles of brain function, and describes presence as a general cognitive function, not specifically related to virtual realities. Virtual reality (VR) is an excellent technology for investigating and taking advantage of all aspects of presence, but a more general interpretation allows the same principles to be applied to a wide range of applications. Functional magnetic resonance imaging (fMRI) was used to study the working human brain in VR. Such data can inform and constrain further discussion about presence. Using two different experimental designs we have investigated both the effect of basic aspects of VR interaction, as well as the neural correlates of disrupted presence in a naturalistic environment. Reality-based brain-computer interaction (RBBCI) is suggested as a concept for summarizing the motivations for, and the context of, applications building on an understanding of human brains in virtual realities. The RBBCI prototype application we developed did not achieve the set goals, but much remains to be investigated and lessons from our evaluation point to possible ways forward. A developed use of methods and techniques from computer gaming is of particular interest.Ett kombinerat perspektiv på den mänskliga hjärnan och datorgenererade virtuella verkligheter motiveras av den senaste utvecklingen inom kognitiv neurovetenskap och människa-datorinteraktion (MDI). Framväxten av nya teorier om den mänskliga hjärnan, tillsammans med en ökande användning av realistisk människa-datorinteraktion, gör det troligt att en bättre förståelse för relationen mellan mänskliga hjärnor och virtuella verkligheter är både möjlig och värdefull. Begreppet "närvaro", som i detta sammanhang beskrivs som den subjektiva känslan av att vara på en plats som känns verklig, kan fungera som en hörnsten i utvecklingen av en sådan förståelse, då datorgenererad närvaro är tätt kopplat till hur mänskliga hjärnor fungerar i virtuella verkligheter. I denna avhandling kopplas närvaro både till teoretiska diskussioner grundade i teorier om den mänskliga hjärnan, och till mätningar av hjärnans aktivitet under realistisk interaktion. De praktiska konsekvenserna av sådana resultat utvecklas vidare med en närmare titt på potentiella tillämpningar. Detta inkluderar utveckling och utvärdering av en prototypapplikation, motiverad av de presenterade principerna. Den teoretiska diskussionen av närvaro i denna avhandling bygger på allmänna principer för hjärnans funktion, och beskriver känslan av närvaro som en generell kognitiv funktion, inte specifikt relaterad till virtuella verkligheter. Virtuell verklighet (virtual reality, VR) är en utmärkt teknik för att undersöka och dra nytta av alla aspekter av närvaro, men en mer allmän tolkning gör att samma principer kan tillämpas på ett brett spektrum av applikationer. Funktionell hjärnavbildning (fMRI) användes för att studera den arbetande mänskliga hjärnan i VR. Sådant data kan informera och begränsa en vidare diskussion av närvaro. Med hjälp av två olika försöksdesigner har vi har undersökt både effekten av grundläggande aspekter av VR-interaktion, och neurala korrelat av störd närvaro i en naturalistisk miljö. Verklighets-baserad hjärna-dator interaktion (reality-based brain-computer interaction, RBBCI) föreslås som ett begrepp för att sammanfatta motiv och kontext för applikationer som bygger på en förståelse av den mänskliga hjärnan i virtuella verkligheter. Den prototypapplikation vi utvecklade uppnådde inte de uppsatta målen, men mycket återstår att utforska och lärdomar från vår utvärdering pekar på möjliga vägar framåt. En vidare användning av metoder och tekniker från dataspel är speciellt intressant.
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Boretzki, Simon [Verfasser]. « Acoustic Radiation Force Impulse Imaging der Niere : Generierung von Normwerten in der ShearWave Elastographie mittels Virtual Touch Tissue Quantification / Simon Boretzki ». Ulm : Universität Ulm, 2017. http://d-nb.info/1122644868/34.
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Vassallo, Daniele. « A virtual coronagraphic test bench for SHARK-NIR, the second-generation high-contrast imager for the Large Binocular Telescope ». Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3422319.
Texte intégralRésumé :
SHARK-NIR is the second-generation high-contrast coronagraphic imager for the Large Binocular Telescope (LBT). In my Ph.D. project I have been involved in the conceptual and final design phase of the instrument. In specific, I developed a simulator in IDL language that operated as a virtual test bench to make a comparative study of several coronagraphic techniques identified as suitable candidates for implementation in the instrument. The simulator is based on physical optics propagation and adopts an end-to-end approach to generate images in presence of several sources of optical aberrations, from atmospheric residuals to telescope vibrations and non common path aberrations (NCPA). In particular, a big effort has been devoted to the optimization of the software efficiency through a dedicated parallelization scheme, to modelling of NCPA spatial and temporal properties, to the investigation of the effects of telescope vibrations and of the impact of the forthcoming upgrade of LBT Adaptive Optics system. I explored the coronagraphic performance in a wide range of observing conditions and characterized the coronagraphs sensitivity to aberrations, misalignments of optical components and chromatism. I also helped developing a data reduction pipeline to process simulated data adopting several algorithms. Simulations results have been used to define a final set of coronagrahic solutions that allow to fulfill the top-level scientific requirements.\\Finally, I validated with simulations the phase diversity approach as a strategy for on-line sensing of NCPA. Simulations contributed to the final choice of the internal DM for both NCPA and fast tip-tilt correction.SHARK-NIR è l'imager ad alto contrasto di seconda generazione per il Large Binocular Telescope. Durante il mio Ph.D. sono stato coinvolto nella fasi di design concettuale e finale dello strumento. In specifico, ho sviluppato un simulatore in IDL che è stato utilizzato come banco di test virtuale per realizzare uno studio comparativo di diverse tecniche coronografiche identificate come possibili candidate a essere implementate nello strumento. Il simulatore è basato sulla propagazione di fronti d'onda e utilizza un approccio end-to-end per generare immagini in presenza di svariate sorgenti di aberrazioni ottiche, da residui atmosferici a vibrazioni e aberrazioni di non-common path (NCPA). Un'attenzione particolare è stata rivolta all'ottimizzazione del software attraverso specifici schemi di parallelizzazione, alla modellizzazione delle proprietà temporali e spaziali delle NCPA e allo studio dell'impatto del prossimo upgrade dei sistema di Ottica Adattiva di LBT. Ho esplorato le performance di diversi coronografi in un ampio range di condizioni osservative e caratterizzato la loro sensibilità ad aberrazioni, disallineamenti e cromatismo. Ho anche contribuito allo sviluppo di una pipeline di riduzione dati rivolta a processare le immagini simulate adottando diversi algoritmi. I risultati delle simulazioni sono stati utilizzati per effettuare una selezione di tecniche coronografiche in grado di soddisfare i requisiti scientifici dello strumento. Infine, ho validato attraverso simulazioni un approccio denominato Phase Diversity il cui fine è misurare on-line le NCPA. Le simulazioni hanno contribuito alla scelta di implementare uno specchio deformabile interno per la correzione simultanea di NCPA e vibrazioni residue ad alta frequenza.
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Heizelmann, Anne [Verfasser]. « Messungen am Musculus trapezius und Musculus erector spinae mit der Virtual Touch Imaging and Quantification-Technologie unter Berücksichtigung verschiedener Einflussfaktoren / Anne Heizelmann ». Ulm : Universität Ulm, 2017. http://d-nb.info/1136956786/34.
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Uematsu, Miho. « Brainstem tau pathology in Alzheimer’s disease is characterized by increase of three repeat tau and independent of amyloid β ». Kyoto University, 2018. http://hdl.handle.net/2433/232128.
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Sanchez, de la Rosa Ruben. « Simulations and virtual clinical trials for the assessment of the added clinical value of angio-tomosynthesis over angio-mammography ». Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLT046.
Texte intégralRésumé :
Contrast Enhanced Spectral Mammography (CESM) and Contrast Enhanced Digital Breast Tomosynthesis (CEDBT) sont des techniques d'imagerie par rayons X à double énergie impliquant l'injection d'un agent de contraste vasculaire. Les deux techniques fournissent des informations sur l'hypervascularisation des lésions par l'absorption de contraste. CESM est une application d'imagerie récemment introduite offrant un meilleur diagnostic du cancer du sein que la mammographie de diagnostique. CEDBT est une technique prometteuse fournissant des informations en trois dimensions, ce qui peut atténuer les limites du CESM. Cependant, sa valeur clinique par rapport à l'examen actuel CESM n'est toujours pas bien comprise. Notre travail vise à évaluer les performance de chaque technique afin de détecter et de caractériser avec précision les différentes absorptions de contraste apparaissant lors des examens cliniques. Cependant, une telle évaluation nécessiterait une vaste base de données de données cliniques avec une représentation complète des divers captages de contraste insérés dans différents contextes hétérogènes, ainsi que la vérité sur le terrain de chaque cas. Au lieu de cela, la nouveauté de notre proposition réside dans l'évaluation des deux techniques à l'aide de données simulées réalistes. Premièrement, nous avons amélioré le réalisme d’un outil de simulation de rayons X analytique. Ensuite, nous avons proposé un nouveau modèle d’absorption de contraste en masse, liée aux lésions mammaires et d’absorption naturelle de contraste de l’anatomie du sein. Enfin, nous avons réalisé un essai clinique virtuel évaluant les performances de détectabilité et de caractérisation du CESM et de la CEDBT à l'aide des outils de simulation développés dans notre travail. Les résultats obtenus montrent que la CEDBT offre une certaine valeur ajoutée clinique par rapport au CESM. En tant que travail futur, les résultats cliniques attendus grâce à la plate-forme de simulation proposée doivent être comparés aux vraies évaluations cliniques lorsqu'un système réel sera disponibleContrast Enhanced Spectral Mammography (CESM) and Contrast Enhanced Digital Breast Tomosynthesis (CEDBT) are dual-energy X-ray imaging techniques involving the injection of a vascular contrast agent. Both techniques provide information on hypervascularization of lesions through contrast uptake. CESM is a recently introduced imaging application providing a better diagnosis of breast cancer than diagnostic mammography. CEDBT is a promising technique providing three-dimensional information, which may alleviate the limitations of CESM. However, its incremented clinical value, compared to the current CESM exam, is still not well understood. This work aims to assess the performance of each technique to detect and accurately characterize the different contrast uptakes appearing in clinical exams. However, such an evaluation would require a large database of clinical data with a complete representation of diverse contrast uptakes. Instead, the novelty of our proposal lies on the evaluation of both techniques using realistic simulated data. First, we improved the realism of an analytic X-ray simulation tool. Then, we proposed a new model for mass-like contrast uptakes related to breast lesions and natural contrast uptake of the breast anatomy. Finally, we performed a Virtual Clinical Trial evaluating the detectability and characterization performance of CESM and CEDBT using the simulations tools developed in our work. The results obtained show that CEDBT offers a certain added clinical value compared to CESM. As a future work, the clinical results anticipated thanks to the proposed simulation platform should be compared to true clinical evaluations when a real system will be available
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Gunn, Therese. « The impact of virtual reality training on the clinical skill and confidence of medical radiation science students ». Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/209310/1/Therese_Gunn_Thesis.pdf.
Texte intégralRésumé :
This study investigates the impact of virtual reality simulation training on medical radiation science students. It evaluates this by comparing clinical skills between students using traditional learning methods and those trained with the inclusion of the VR simulator and assesses the impact on student clinical confidence. This study's outcomes have highlighted the advantages of using such an innovative technique whilst demonstrating that the software itself is not enough to guarantee student learning. Instead, it requires purposeful inclusion into the curriculum with educators ensuring knowledge of the technology and appreciating the students' individual learning needs.
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Lauthers, Chad M. « The effects of stereoscopic technologies on subjects' ability to perform a Lego block construction task ». Connect to this title online, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1143132334.
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Jeffrey, Stuart. « Three dimensional modelling of Scottish early medieval sculpted stones ». Thesis, Connect to electronic version, 2003. http://ads.ahds.ac.uk/catalogue/library/theses/jeffrey%5F2004/index.cfm.
Texte intégralRésumé :
Thesis (Ph. D.)--University of Glasgow, 2003.Accompanied by CD-ROM. Ph. D. thesis submitted to the Department of Archaeology, University of Glasgow, 2003. Includes bibliographical references. Print version also available.
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Dalgarno, Barney John. « Characteristics of 3D environments and potential contributions to spatial learning ». Access electronically, 2004. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20050114.092913/index.html.
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Jovanovski, Diana. « Cognitive set shifting using functional magnetic resonance imaging (fMRI) and virtual reality (VR) a comparison between a traditional and a novel ecologically-valid executive function task / ». Full text available, 2005. http://images.lib.monash.edu.au/ts/theses/jovanovski.pdf.
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Bergqvist, Emil. « Spatial orientation & ; imagery : What are the gender differences in spatial orientation and mental imaging when navigating a virtual environment with only auditory cues ? » Thesis, Högskolan i Skövde, Institutionen för informationsteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-11270.
Texte intégralRésumé :
This thesis analyses the gender differences in spatial orientation and mental imagery when navigating a virtual environment with only auditory cues. A prototype was developed for an iPod Touch device to evaluate possible gender difference in performance of orientation. A sketch map task was conducted to externalize the participants’ mental representation they achieved from the environment. Questionnaires were used to collect data on previous video game experience, spatial orientation self-assessment and spatial anxiety. A post-interview was conducted to gather qualitative information from the participants on how they experienced the experiment and to collect some background about them. In total, 30 participants (15 females, 15 males) with tertiary education participated in the experiment. The result indicates that there are gender differences in time to complete the tasks in the virtual environment. In the sketch map task, there were no gender differences in how well they sketch and externalize their mental representation of the environment. The post-interview showed tendencies that there are possible gender differences in vividness of mental imagery.
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Minz, Jacob Rajkumar. « Physical Design Automation for System-on-Packages and 3D-Integrated Circuits ». Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14012.
Texte intégralRésumé :
The focus of this research was to develop interconnect-centric
physical design tools for 3D technologies.
A new routing model for the SOP structure was developed which
incorporated the 3D structure and formalized the resource structure
that facilitated the development of the global routing tool.
The challenge of this
work was to intelligently convert the 3D SOP routing problem into a set
of 2D problems which could be solved efficiently.
On the lines of MCM, the global routing problem
was divided into a number of phases namely, coarse pin distribution,
net distribution, detailed pin distribution, topology generation, layer
assignment, channel assignment and local routing. The novelty in this
paradigm is due to the feed-through vias needed by the nets which traverse
through multiple placement layers. To gain further improvements in
performance, optical
routing was proposed and a cost analysis study was done. The areas for
the placement of waveguides were efficiently determined, which reduced
delays and maximized utilization.
The global router developed was integrated into a simulated-annealing based
floorplanner to investigate trade-offs of various objectives. Since power-supply
noise suppression is of paramount importance in SOP, a model was developed
for the SOP power-supply network. Decap allocation, and
insertion were also integrated into the framework. The challenges
in this work were to integrate computationally intensive analysis tools with
a floorplanning that works to its best efficency provided the evaluation of
the cost functions are rapid. Trajectory-based approaches were used to sample
representative data points for congestion analysis and interpolate the
the congestion metric during the optimization schedule. Efficient
algorithms were also proposed for 3D clock routing, which acheived
equal skews under uniform and worst thermal profiles. Other
objectives such as wirelength, through-vias, and
power were also handled.
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Siqueira, Dimytri Alexandre de Alvim. « Utilização do ultra-som intracoronário com Histologia Virtual® na identificação de lesões propensas à reestenose após o implante de stents ». Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/98/98131/tde-19092011-073142/.
Texte intégralRésumé :
A intervenção percutânea com implante de stents constitui-se na principal forma de revascularização miocárdica empregada, e associa-se à redução de sintomas, à melhoria na qualidade de vida e ao aumento da sobrevida em pacientes acometidos por síndrome coronária aguda. Entretanto, o implante de stents pode acompanhar-se de exagerada hiperplasia intimal, principal determinante da reestenose destes dispositivos. Diversos fatores clínicos, anatômicos e técnicos associam-se a maiores taxas de reestenose, porém a hipótese de que o tipo ou a composição da lesão aterosclerótica tratada possa correlacionar-se com o fenômeno ainda não foi esclarecida. Determinar a relação entre a composição da placa aterosclerótica tratada conforme análise pela Histologia Virtual® - e a magnitude da hiperplasia intimal após o implante de stents farmacológicos e não-farmacológicos. No período de setembro de 2008 a novembro de 2009, selecionamos 52 pacientes prospectivos com o diagnóstico de síndrome coronária aguda com ou sem supra ST, submetidos à cinecoronariografia e candidatos à intervenção percutânea. Estes foram randomizados para o tratamento com stents farmacológicos com sirolimus (Cypher® Cordis, Johnson & Johnson) ou com stents não-farmacológicos (Driver®,Medtronic Inc.). O ultra-som com Histologia Virtual® foi realizado antes do tratamento das lesões culpadas, e correlacionou-se o porcentual dos componentes fibrótico, fibrolipídico, núcleo necrótico e cálcio com o grau de hiperplasia intimal, em reestudo ultrasonográfico realizado aos 9 meses. A média de idades foi de 55,3 anos (DP 4,9 anos), sendo 77% homens. Não foram verificadas diferenças significativas entre os grupos no que se refere às variáveis clínicas e angiográficas. A maioria dos pacientes apresentava obstrução coronária uniarterial, e o vaso mais freqüentemente tratado foi a descendente anterior. À Histologia Virtual®, não foram detectadas diferenças em relação ao tipo de placa tratada, sendo predominantes as lesões do tipo fibroateroma e fibroateroma calcificado. O tecido fibrótico foi o componente preponderante [59,6% (DP 15,8%) do volume total das placas analisadas], e cerca de 20% do volume das lesões era composto por núcleo necrótico. Após 9 meses, o reestudo ultrasonográfico foi realizado em 49 (94%) dos pacientes. Tanto o volume como o porcentual de hiperplasia intimal foram significativamente maiores no grupo tratado com stents não-farmacológicos [60,8 mm3 [DP 32 mm3] versus 14 mm3 (DP 9,2 mm3), p<0,0001 e [31,9% (DP 12,9%) versus 8,2% (DP 7,6%) , p<0,0001, respectivamente]. Contudo, não foi observada associação entre os porcentuais dos componentes fibrótico (corr. 0,038, p=0,81), fibrolipídico (corr. 0,109, p=0,49), cálcio (corr. -0,073, p=0,64) e núcleo necrótico (corr. -0,062, p=0,69) das lesões tratadas com o tecido neointimal intra-stent. Os resultados desta investigação prospectiva e randomizada indicam que as informações providas pela Histologia Virtual® na caracterização das placas ateroscleróticas não auxiliam na identificação de lesões mais propensas à reestenose, após o implante de stents farmacológicos e não-farmacológicos.To the present, little is known about the correlation between modifications in plaque composition at stent edges and the changes in vessel geometry. This study sought to evaluate, by serial grey-scale intravascular ultrasound (IVUS) and Virtual Histology(TM), the modifications in plaque composition at the edges of drug-eluting and bare-metal stents and the correlation of these findings with changes in the measuremntes of vessel, lumen and plaque area at those segments. Single-center, prospective and randomized (1:1) evaluation of 40 patients with acute coronary syndrome treated with bare-metal (Driver(TM), n=20 patients) or drug-eluting stents (Cypher(TM), n=20 patients). Following stent deployment, all individuals underwent gray scale IVUS and Virtual Histology(TM) evaluation, which were repeated at nine months. Primary endpoint included the modification in vessel, lumen and plaque area and in the composition of the plaque in the mean time between the baseline and follow-up procedure. Additionally, we tried to determine a correlation between plaque composition variation and changes in vessel geometry. At the proximal edge of both drug-eluting and bare-metal stents there was a trend to positive vessel remodeling which compensated the modest increase in plaque area. At the distal edge, patients treated with drug-eluting stents had less plaque growth resulting in a larger lumen area at follow-up. By Virtual Histology, there was a marked reduction in the % of fibrotic tissue and necrotic core in both edges of the two stents and a positive, strong correlation was seen between increase in % of fibrofatty component and augmentation in plaque area(r=0.78, p=0.01). The use of drug-eluting stents was not associated with \"edge effect\". On the contrary, patients treated with these devices experienced less plaque growth, especially at the distal edge of the stents. Modifications in plaque composition, with increase in fibrofatty content, might partially explain these findings.
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Li, Zhijin. « Task-based optimization of 3D breast x-ray imaging using mathematical observers ». Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLN038.
Texte intégralRésumé :
La mammographie, une modalité 2D d'imagerie du sein par rayons X, a montré son efficacité pour réduire la mortalité par cancer du sein. Aujourd'hui, la tomosynthèse numérique du sein, une modalité 3D d'imagerie du sein par rayons X, prend une place de plus en plus importante dans la pratique clinique, et est reconnue de plus en plus souvent comme ayant le potentiel de remplacer la mammographie dans un proche avenir. Pour évaluer plusieurs aspects de la tomosynthèse, des études cliniques sont nécessaires. Mais les études cliniques sont coûteuses et présentent des risques supplémentaires pour les patientes dus à l'utilisation de radiations ionisantes. Les études cliniques virtuelles ont pour objectif d'offrir une approche alternative en utilisant des simulations numériques. Dans cette thèse, nous nous intéressons à plusieurs éléments intervenants dans une telle étude clinique virtuelle. Dans un premier temps, nous analysons l'état de l'art sur la caractérisation analytique des champs aléatoires 3D pour la simulation de la texture du sein par rayons X. Nous nous intéressons aussi à l'estimation de caractéristiques statistiques des images du sein par rayons X (densité, indice spectral). Puis nous développons un nouveau modèle de texture 3D du sein basé sur la géométrie stochastique, et qui permet de simuler des images 2D et 3D réalistes du sein. Nous considérons le problème de l'inférence d'un tel modèle à partir d'une base d'images cliniques 3D. Ensuite, nous développons un observateur mathématique basé sur la théorie textit{a contrario} de la perception visuelle, pour modéliser la détection des microcalcifications par des radiologues dans des images 2D et 3D du sein. Tous ces composants sont utilisés pour implémenter une étude clinique entièrement numérique. La pertinence des résultats obtenus montre l'utilité de ces études cliniques virtuelles et nous incite à en développer de plus élaborées dans le futurFull field digital mammography, a 2D x-ray breast imaging modality has been proved to reduce the breast cancer mortality. Today, digital breast tomosynthesis, a 3D x-ray breast imaging modality, is being integrated in clinical practice and is believed to replace standard mammography in the near future. To assess the clinical performance of various aspects of tomosynthesis, clinical trials are needed. Clinical trials are burdensome, expensive and may impose increased risk to the patient due to additional radiation exposure. Virtual Clinical Trials aim to offer a more efficient alternative by using computational components. Today, active research is ongoing to develop computational components dedicated to 2D and 3D breast imaging, especially to 3D tomosynthesis. This thesis aims to advance several aspects in the development of Virtual Clinical Trials. First, we focused on analytical characterization of state-of-the-art 3D random field breast texture models. The estimation of statistical characteristics (breast density, spectral index) from clinical x-ray breast images was also studied. Next, we proposed a mathematically traceable 3D breast texture model based on stochastic geometry, that allows to simulate realistic 2D and 3D images. The statistical inference of the texture model parameters from a database of clinical 3D breast images was also tackled. We then developed a mathematical observer based on the textit{a contrario} theory, that allows to model the microcalcification detection process by radiologists in 2D and 3D breast images. Finally, these two proposed components were applied to implement a virtual clinical trial experiment, demonstrating their potential in the conduct of more advanced virtual clinical studies in the future
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Villamil, Marta Becker. « Modelagem e simulação da articulação temporomandibular ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/18247.
Texte intégralRésumé :
A simulação de articulações baseada em anatomia, além de melhorar o realismo de animações do corpo humano na área da computação gráfica, tem se tornado uma importante ferramenta no auxílio ao diagnóstico médico e nas estimativas de resultados pósoperatórios, simplificando e melhorando o planejamento cirúrgico. Entretando, para uso efetivo em aplicações médicas, é necessário modelar as articulações de acordo com individualidades de cada paciente. Neste contexto, este trabalho propõe um modelo do conjunto de articulações temporomandibulares (ATMs) baseado em anatomia, modelo esse construído a partir de dados reais que representam a geometria e o movimento mandibular de um paciente normal. A modelagem aqui proposta apresenta uma topologia de duas juntas interdependentes, de maneira que o objeto geométrico que representa a mandíbula é associado a mais de uma junta. O modelo geométrico foi obtido de um indivíduo com ATM normal. O modelo padrão de como a ATM se movimenta é obtido a partir de cinemática inversa aplicada aos pontos da curva incisal capturada do mesmo indivíduo. Para reproduzir o movimento da mandíbula, a simulação trata as colisões entre os ossos da mandíbula e do crânio, facilitando, desta maneira, o entendimento de como forma e função interagem neste complexo sistema. Todas as fases da modelagem foram verificadas usando dados reais. Um modelo como este tem um grande potencial de prover dados úteis para médicos e dentistas realizarem diagnóstico de patologias e planejamento de cirurgias. O modelo foi usado para analisar como a forma e função são relacionadas nos movimentos de depressão e elevação da mandíbula e na mastigação. É apresentada também a aplicação do mesmo modelo de movimento da ATM para diferentes modelos de mandíbulas e maxilas, representando diferentes pessoas e diferentes patologias. Para atingir este objetivo, a malha do crânio padrão foi modificada manualmente para simular patologias conhecidas. Além disso, foram usados dados reais advindos de análises cefalométricas para modificar o modelo geométrico original com o intuito de representar a morfologia de pessoas diferentes sem submetê-las a exames de tomografia.Beyond improving the realism of human body animation in entertainment graphics applications, the simulation of anatomical joints has become an important tool in aiding medical diagnosis as well as in the estimation of postoperative results, simplifying and improving surgical planning. However, for effective use in such medical applications, it is necessary to model the articulation in accordance with specificities of each patient. In this context, this work proposes a model of the temporomandibular joints (TMJs) set based on anatomy and built from real data representing geometry and movement of a normal patient. The model proposed here presents a topology of interdependent joints in such way that the geometric object that represents the jaw is associated to more than one joint. A geometric model of the skull was obtained from an individual with a normal TMJ. The basic model of how TMJ moves is obtained from inverse kinematics applied to the points of the incisal motion path captured from the same individual. To actually reproduce the movement of the mandible, the simulation treats the collision between the bones of the jaw and skull, facilitating the understanding of how form and function interact in this complex system. All phases of the modeling process were checked using real data. A model like this has a great potential to provide physicians and dentists with useful data for diagnosis and surgery planning. We use our model to analyze how form and function are closely related in the movements of opening and closing the mouth as well as mastication. We also show how the same model of TMJ movement can be applied to different mandible-maxilla models, representing different people and different pathologies. To accomplish that we manually modified the standard skull to simulate different, well-know pathologies but also used real data from cefalometric analysis to tailor our geometric model to represent skull morphology of different people without submitting them to computer tomography exams.
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Madai, Vince István [Verfasser]. « Virtual pre-embedding labeling : a method for correlative fluorescence and electron microscopic imaging and double-labeling in the central nervous system of the rat / Vince István Madai ». Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2012. http://d-nb.info/1027307558/34.
Texte intégral
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Madai, Vince Istvan [Verfasser]. « Virtual pre-embedding labeling : a method for correlative fluorescence and electron microscopic imaging and double-labeling in the central nervous system of the rat / Vince István Madai ». Berlin : Medizinische Fakultät Charité - Universitätsmedizin Berlin, 2012. http://d-nb.info/1027307558/34.
Texte intégral