Дисертації з теми "Virtual tomography"
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1
Downham, Alexander David. "True 3D Digital Holographic Tomography for Virtual Reality Applications." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1513204001924421.
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Аврунін, О. Г., L. A. Averyanova, V. M. Golovenko, and O. Sklyar. "E-Learning of Functioning Principles Medical Intrascopy Systems." Thesis, Varna, Bulgaria, 2007. http://openarchive.nure.ua/handle/document/8276.
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Nicolson, Heather Johan. "Exploring the Earth's subsurface with virtual seismic sources and receivers." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5726.
Повний текст джерелаАнотація:
Traditional methods of imaging the Earth’s subsurface using seismic waves require an identifiable, impulsive source of seismic energy, for example an earthquake or explosive source. Naturally occurring, ambient seismic waves form an ever-present source of energy that is conventionally regarded as unusable since it is not impulsive. As such it is generally removed from seismic data and subsequent analysis. A new method known as seismic interferometry can be used to extract useful information about the Earth’s subsurface from the ambient noise wavefield. Consequently, seismic interferometry is an important new tool for exploring areas which are otherwise seismically quiet, such as the British Isles in which there are relatively few strong earthquakes. One of the possible applications of seismic interferometry is the ambient noise tomography method (ANT). ANT is a way of using interferometry to image subsurface seismic velocity variations using seismic (surface) waves extracted from the background ambient vibrations of the Earth. To date, ANT has been used to successfully image the Earth’s crust and upper-mantle on regional and continental scales in many locations and has the power to resolve major geological features such as sedimentary basins and igneous and metamorphic cores. In this thesis I provide a review of seismic interferometry and ANT and apply these methods to image the subsurface of north-west Scotland and the British Isles. I show that the seismic interferometry method works well within the British Isles and illustrate the usefulness of the method in seismically quiet areas by presenting the first surface wave group velocity maps of the Scottish Highlands and across the British Isles using only ambient seismic noise. In the Scottish Highlands, these maps show low velocity anomalies in sedimentary basins such as the Moray Firth and high velocity anomalies in igneous and metamorphic centres such as the Lewisian complex. They also suggest that the Moho shallows from south to north across Scotland, which agrees with previous geophysical studies in the region. Rayleigh wave velocity maps from ambient seismic noise across the British Isles for the upper and mid-crust show low velocities in sedimentary basins such as the Midland Valley, the Irish Sea and the Wessex Basin. High velocity anomalies occur predominantly in areas of igneous and metamorphic rock such as the Scottish Highlands, the Southern Uplands, North-West Wales and Cornwall. In the lower crust/upper mantle, the Rayleigh wave maps show higher velocities in the west and lower velocities in the east, suggesting that the Moho shallows generally from east to west across Britain. The extent of the region of higher velocity correlates well with the locations of British earthquakes, agreeing with previous studies that suggest British seismicity might be influenced by a mantle upwelling beneath the west of the British Isles. Until the work described in Chapter 6 of this thesis was undertaken in 2009, seismic interferometry was concerned with cross-correlating recordings at two receivers due to a surrounding boundary of sources, then stacking the cross-correlations to construct the inter-receiver Green’s function. A key element of seismic wave propagation is that of source-receiver reciprocity i.e. the same wavefield will be recorded if its source and receiver locations and component orientations are reversed. By taking the reciprocal of its usual form, in this thesis I show that the impulsive-source form of interferometry can also be used in the opposite sense: to turn any energy source into a virtual sensor. This new method is demonstrated by turning earthquakes in Alaska and south-west USA into virtual seismometers located beneath the Earth’s surface.
4
Malusek, Alexandr. "Calculation of scatter in cone beam CT : Steps towards a virtual tomograph." Doctoral thesis, Linköping : Department of Medical and Health Sciences, Linköping University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11275.
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Kang, Fatima Maria de Angelis. "Análise quantitativa de modelos de prototipagem rápida baseados em dados de tomografia volumétrica, por meio de inspeção de engenharia reversa tridimensional." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/23/23139/tde-27102009-095334/.
Повний текст джерелаАнотація:
O objetivo neste estudo foi avaliar a reprodutibilidade quantitativa dos modelos tridimensionais gerados por meio de imagens de tomografia volumétrica de feixe cônico, obtidos por dois tomógrafos volumétricos NEWTOM 9000 DVT (i- (Quantitative Radiology, Verona, Itália) e i-CAT (Imaging Sciencies Int. Hatfield, Pensilvânia. Estados Unidos da América), submetidos à inspeção de engenharia reversa. Uma mandíbula macerada foi digitalizada por meio do SCANNER 3D VIVID 910, com precisão de 0,01 mm, associado à fotometria digital, sendo utilizado o software GEOMAGIC STUDIO, e assim obteve-se um modelo considerado padrão ouro. Posteriormente realizamos o exame de tomografia volumétrica de feixe cônico, na mesma mandíbula nos dois tomógrafos volumétricos, obtendo-se assim os modelos virtuais tridimensionais. Por meio de um alinhamento das geometrias do padrão ouro com os modelos virtuais resultantes da tomografia do aparelho NEWTOM 9000 DVT e do i-CAT, foram observadas as possíveis discrepâncias. Concluímos que estas alterações encontradas após a análise quantitativa das diversas regiões foram menores nas imagens adquiridas pelo tomógrafo volumétrico de feixe cônico modelo i-CAT, e portanto possibilitam a geração de modelos de prototipagem rápida de melhor qualidade.The purpose of this study was to evaluate the quantitative reproductability of the 3d models created using CT images. The images used were obtained from two different cone beam tomographs: NEWTOM 9000 DVT (Quantitative Radiology, Verona, Italy) and i-CAT ( Imaging Sciences Int., Hatfield, EUA) and then inspected through reverse engineering processing software. A dry mandible was digitalized using a 3D Scanner VIVID 910 and the GEOMAGIC STUDIO software to obtain a 0,01mm precision model considered to be our gold standard. Two distinct 3D virtual models were then created after submitting the same dry mandible to a cone beam exam on both tomographs (NEWTOM and i-Cat). Possible discrepancies between the 3D models and the gold standard were analyzed through and alignment of their geometries. After evaluating the discrepancies at the different sites of the models, we concluded that the virtual model obtained using the i-Cat tomograph images was more accurate and therefore of greater quality.
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Chouika, Nabil. "Generalized Parton Distributions and their covariant extension : towards nucleon tomography." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS259/document.
Повний текст джерелаАнотація:
Les Distributions de Partons Généralisées (GPDs) encodent les corrélations entre impulsion longitudinale et position transverse des partons dans les hadrons et permettent d'imager la structure du nucléon en 2+1 dimensions. Elles ont été étudiées théoriquement et expérimentalement pendant deux décennies et une nouvelle ère expérimentale débute actuellement (à Jefferson Lab et COMPASS, mais aussi à l'avenir à un collisionneur électron-ion) pour les extraire avec grande précision. La difficulté est que seul un accès expérimental indirect est possible, à travers divers canaux de diffusion exclusive et les observables associés. Cela implique de prendre nécessairement en compte les nombreuses contraintes théoriques si l'on veut concevoir des modèles fiables pour la phénoménologie. En particulier, deux contraintes cruciales sont les propriétés de "polynomialité" et de "positivité". L'approche de cette thèse consiste à tirer partie des deux propriétés en modélisant d'abord les fonctions d'onde sur le cône de lumière des premiers états de Fock du nucléon, permettant d'obtenir une GPD dans la région appelée DGLAP via overlap où le nombre de partons est conservé, puis l'étendre de manière covariante à la région ERBL, avec une inversion de transformée de Radon. In fine, le but est d'appliquer cette procédure à un modèle de quark-constituant pour GPDs de valence, ce qui permettrait de produire de manière inédite pour ce genre de modèle des résultats à comparer à l'expérience (sur le processus de diffusion Compton profondément virtuelle en l’occurrence). Pour atteindre cette objectif, on utilise la librairie PARTONS sous différentes hypothèses perturbativesGeneralized Parton Distributions (GPDs) encode the correlations between longitudinal momentum and transverse position of partons inside hadrons and can give access to a picture of the nucleon structure in 2+1 dimensions. They have been studied theoretically and experimentally for almost two decades and a new experimental era is starting (at JLab and COMPASS currently, and in the future at an EIC) to extract them. The difficulty is that only an indirect experimental access is so far possible, through different exclusive channels and various observables. Therefore, one has to take into account the many theoretical constraints to be able to produce accurate models and rely on their phenomenology. Two important constraints are called the polynomiality and positivity properties. The approach of this thesis is to make use of both of them by first modeling low Fock states light-front wave-functions, which gives a GPD in the DGLAP region by a parton number conserved overlap, and then covariantly extending this GPD to the ERBL region, through an inverse radon transform. In fine, the goal is to apply this on a constituent quark-like model for valence GPDs, which would allow to produce a phenomenological output (on DVCS data for instance) from this kind of models, which was impossible before. We make use of the versatile PARTONS framework to achieve this under various perturbative QCD assumptions
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Steuwe, Andrea [Verfasser], and Hans-Ulrich [Akademischer Betreuer] Kauczor. "Spatially resolved quantification of radiation exposure associated with computed tomography examinations – Towards the development of virtual dosimetry / Andrea Steuwe ; Betreuer: Hans-Ulrich Kauczor." Heidelberg : Universitätsbibliothek Heidelberg, 2019. http://d-nb.info/1193347297/34.
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Schanandore, James. "Examination of Age at Death Methods and the Effects on Estimation Accuracy when Applied to Computed Tomography Scans and Virtual Models of Mummies." Diss., North Dakota State University, 2015. http://hdl.handle.net/10365/24808.
Повний текст джерелаАнотація:
Three-dimensional (3D) medical imaging provides a method to non-invasively examine the sub-surface structures of a mummified body, particularly the skeleton. The unique nature of both natural and anthropogenic mummification processes causes inconsistencies for estimating accurate age at death for a particular mummy or group of mummies. These inaccuracies are compounded when age at death methods are used in relation to 3D virtual models. There is a need for the examination of methods being used in mummy case studies and how they are being applied to the 3D virtual models.
My research encompassed three studies that addressed the relationship of and the variability when estimating age at death of mummies using radiological imaging. In one study, 146 published case studies were examined for which methods were used to estimate age at death. This study found that articles often provided an assessment of age, but many failed to specify the methods used to calculate the estimated age, and if specified methods were limited to certain areas of the body.
In a second study, a cohort of age at death methods was applied to a sample of 17 adult mummies and it was determined that some methods do not transpose well and consequently provided inaccurate age at death estimations when applied to 3D virtual models. Modifications to traditional osteological approaches for age estimation were sometimes necessary due to the presence of soft tissue and post-mortem changes to the body. This study proposes that more methods are needed that utilize the tools available for radiological images in order to limit the variability of transposing a traditional age at death method to virtual 3D models.
In the third study, the rim height of the auricular surface was measured using computed tomography scans of 97 living or recently deceased individuals’. These measurements targeted areas around the edge of the surface, for example the height of the apex above the surface. The rim height above the surface produced models that can accurately predict age at death.
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Rosa, Vera Lúcia Mestre. "Cefalostato virtual-posicionamento inicial para a padronização na marcação de pontos craniométricos em imagens obtidas por tomografia computadorizada, para uso em cefalometria." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/23/23139/tde-19122009-122434/.
Повний текст джерелаАнотація:
Objetivo: O desenvolvimento da tecnologia em diagnóstico odontológico por imagem através dos Tomógrafos Computadorizados por Feixe Cônico, tornou possível e acessível a avaliação cefalométrica através de reconstruções volumétricas do crânio. Parâmetros baseados em evidências científicas são necessários para implementar o seu uso. Alguns parâmetros utilizados na cefalometria convencional (bidimensional) deverão ser esquecidos, outros deverão ser adaptados, outros, ainda, deverão ser criados. Propomos aqui a criação de um Cefalostato Virtual para orientação do crânio em TC, com a utilização de pontos intracranianos, que são mais estáveis. Também propomos a criação do ponto TS e da linha TS-Pg em substituição ao ponto S e ao eixo Y de crescimento de Downs, respectivamente. Além disso, propomos a linha Ba-Op como referência para casos de assimetria faciais onde não é possível a utilização do plano Horizontal de Frankfurt, em casos, por exemplo, de síndromes que afetem os pontos de referências mais externos. Métodos: 49 crânios pertencentes ao do Museu de Anatomia UNIFESP, foram escaneados em um tomógrafo computadorizado por feixe cônico (TCFC), na clínica ISOOrthographic, São Paulo. As pontuações foram realizadas em dois momentos, com espaçamento de uma semana. Foram calculadas estatisticamente medidas-resumo (média, quartis, mínimo, máximo e desvio padrão). Foram calculadas também as correlações intraclasse e correlações de Pearson entre o Eixo Y (S-Gn) e linha entre os pontos TS e Pg. Resultados: Apesar de se observar uma baixa reprodutibilidade nas coordenadas, para os pontos CE, Pg e Gn, foi observada alta correlação entre as medidas angulares em questão. Para descrever a inclinação do Eixo Y em função da inclinação da Linha TS e Pg adotou-se um modelo de regressão linear simples descrito pela equação abaixo: Ang Sö- Gn = 0,989 Ang TS Pgi i Conclusões: o uso do Cefalostato Virtual na orientação de Crânios em Tomografia Computadorizada é factível e favorece a reprodução do posicionamento craniano; apesar da baixa reprodutibilidade intra observador dos pontos CE, Pg e Gn, novos critérios tridimensionais na definição destes pontos poderiam aumentar a precisão na sua localização; a alta reprodutibilidade intra observador para os pontos Op, TS e N, sugere que os critérios anatômicos próprios das estruturas estudadas favorecem a sua determinação; o ponto TS apresentou maior reprodutibilidade do que o ponto S, embora esta diferença não tenha sido estatisticamente significante, podendo-se substituir o ponto S pelo TS em estudos futuros; existe alta correlação entre a linha entre os pontos TS e Pg e o Eixo Y; a avaliação do comportamento da inclinação da linha orbitomeática (HF) com relação à linha Básio-Opístio sugere que na presença de alterações cranianas este relacionamento propicie auxílio no diagnóstico das alterações craniofaciais.Objective: The development of new technology in dental diagnosis by cone beam CT (CBCT) image, made possible and accessible the realization of cephalometric evaluation through volumetric reconstructions of the skull. Scientific parameters with evidence-based are needed to implement its use. Some parameters used in conventional cephalometry (2D) maybe need to be forgotten, others should be adapted, and others still to be created. In this research we propose to create a Virtual Cephalostat orientation of the skull in CT, with the intracranial landmarks, because they are more stable. We propose the creation of landmark TS (Tubercle Sella) and the TS-Pg line to replace the landmark S (Sella) and the Y-axis of growth (Downs), respectively. Furthermore, we propose to use the Basion-Opistion line as a reference for cases of craniofacial asymmetry where is not possible to use the Frankfurt horizontal plane, as in some cases of syndromes that affects the most external landmarks. Methods: 49 skulls of Anatomy Museum of UNIFESP Federal University of São Paulo, were scanned in a CBCT. The analyses were performed in 2 stages, within 1-week space. Statistics measurements were calculated (mean, quartiles, minimum, maximum and standard deviation). We also calculated the intraclass correlations (ICC) and the Pearson correlations between the Y axis (S-Gn) and the line between landmarks TS-Pg. Results: Even if there is a low reproducibility in the coordinates for landmarks EC (Ethmoidal Crest), Pg and Gn it was observed a high correlation between the angular measures in question. To describe the inclination of the Y axis according to the slope of the line adopted TS and Pg a simple linear regression model is used, showed by the equation bellow: Ang Sö- Gn = 0,989 Ang TS Pgi i Conclusions: The use of the Virtual Cephalostat in orientation of skulls using CBCT is feasible and facilitates the reproduction of the skull position, despite the low intra observer reproducibility of landmarks EC, Pg and Gn, new 3D criteria in the definition of these landmarks could increase the precision in its location. The high intra observer reproducibility at the landmarks Op, N and TS, suggests that the anatomical criteria themselves promote their reliability; The TS landmark showed a higher reproducibility than the S landmark, even though the difference was not statistically significant, and it should be replaced by the landmark TS in future studies. There is a high correlation between the TS - Pg line and Y-axis. The relationship between the slope of the HF plane and Ba -Op line suggests that in the presence of the alteration of morphology in craniofacial structure, this relationship offer help in the diagnosis of craniofacial changes.
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Töpperwien, Mareike [Verfasser], Tim [Akademischer Betreuer] Salditt, Tim [Gutachter] Salditt, and Florian [Gutachter] Rehfeldt. "3d virtual histology of neuronal tissue by propagation-based x-ray phase-contrast tomography / Mareike Töpperwien ; Gutachter: Tim Salditt, Florian Rehfeldt ; Betreuer: Tim Salditt." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://d-nb.info/1162339675/34.
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Freitas, Aurea do Carmo Pêpe Agulha de. ""Avaliação inter-observador da aplicação da sinuscopia virtual, comparada com as imagens obtidas por meio da tomografia computadorizada helicoidal, nos comprometimentos sinusais"." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/23/23139/tde-06062005-113501/.
Повний текст джерелаАнотація:
Objetivo: Comparar as imagens obtidas por meio da sinuscopia virtual com aquelas adquiridas por meio da tomografia computadorizada helicoidal, quando da interpretação dos comprometimentos sinusais, considerando as opiniões dos médicos otorrinolaringologistas e radiologistas odontológicos, com a finalidade de validação do método da sinuscopia virtual. Métodos: Foram utilizadas informações obtidas por meio da observação de imagens de 20 casos pertencentes ao arquivo docente, da Unidade de Imagens Dento-Maxilo-Facial da Clínica Felix Boada, em Caracas-Venezuela. Os referidos casos apresentaram imagens adquiridas por meio da tomografia computadorizada helicoidal e imagens obtidas por meio da sinuscopia virtual. As imagens foram analisadas por 2 grupos de observadores, 10 médicos otorrinolaringologistas e 10 radiologistas odontológicos, que responderam a um questionário previamente elaborado. Resultados: Os resultados foram avaliados pelos testes estatísticos de média aritmética, mediana, desvio padrão, análise de médias, percentuais globais, teste nãoparamétrico de Kruskal-Wallis e teste não-paramétrico de Wilcoxon. Conclusões: Para os médicos otorrinolaringologistas e radiologistas odontológicos faz-se importante, a associação das imagens obtidas por meio da sinuscopia virtual com as imagens axiais obtidas por meio da tomografia computadorizada helicoidal na interpretação de um comprometimento sinusal. Os radiologistas odontológicos acharam que as imagens axiais obtidas por meio da tomografia computadorizada helicoidal já eram esclarecedoras, na avaliação dos casos, embora também recomendassem a sinuscopia virtual. Nos casos considerados fáceis, a aplicação da sinuscopia virtual foi evidente, porém nos casos difíceis não contribuiu. A sinuscopia virtual isoladamente não oferece condições para a conclusão do diagnóstico de uma afecção sinusal.Purpose: To compare the images obtained by means of virtual sinuscopy with those formed by means of helical computerized tomography during the interpretation of sinusal compromise taking into consideration the opinions of otorhinolaryngologists and odontological radiologists aiming to validate the method of virtual sinuscopy. Methods: Information obtained through the observation of images of 20 cases belonging to the professorial file, of the Dental Maxillo - Facial Unit of Images of Félix Boada Clinic in CaracasVenezuela were used. The cases mentioned above showed images formed by means of the helical computerized tomography and images formed by means of the virtual sinuscopy. The images were analysed by 2 groups of observers, 10 otorhinolaryngologists and 10 odontological radiologists who answered a questionnaire previously prepared. Results: The results were appraised through statistical tests of arithmetic average, median, standard deviation, average analysis, global percentile, Kruskal-Wallis non-parametric test and Wilcoxon non-parametric test. Conclusions: To the otorhinolaryngologists and odontological radiologists it is important, the association of the images obtained by means of the virtual sinuscopy with the axial images formed by means of helical computerized tomography in the interpretation of a sinusal compromise. The odontological radiologists thought the axial images formed by means of the helical computerized tomography were already elucidatory, for the evaluation of the cases although they also recommended the virtual sinuscopy. In the cases regarded as easy ones, the application of the virtual sinuscopy was evident, but in the difficult cases it didnt contribute. The virtual sinuscopy used singly doesnt offer conditions for a diagnostic conclusion of the sinusal affection.
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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.
Повний текст джерелаАнотація:
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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Botega, Leonardo Castro. "Análise de imagens tomográficas da Ciência do Solo em ambiente de realidade virtual." Universidade Federal de São Carlos, 2008. https://repositorio.ufscar.br/handle/ufscar/412.
Повний текст джерелаАнотація:
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Previous issue date: 2008-08-28This work presents a Virtual Reality environment dedicated to the analysis of tomographic images of Soil Science. Its architecture uses models proceeding from a volumetric (3-D) reconstruction algorithm, summed with several graphics processes of manipulation and visualization, in a way to provide immersion and interaction of the user with the virtual scene. Its validation was performed based on a case study involving the analysis of the porosity of the agricultural soil samples, which presents preferential paths for the water and solute flow (fingering). Results illustrate the consistent verification of the preferential paths of the agricultural soil samples, analyzed based on the developed environment.
Este trabalho apresenta um ambiente de Realidade Virtual dedicado à análise de imagens tomográficas da Ciência do Solo. Sua arquitetura utiliza modelos provenientes de um algoritmo de reconstrução volumétrica (3-D) adicionado a diversos processos gráficos de manipulação e visualização, de tal forma a possibilitar imersão e interação do usuário com a cena virtual. Sua validação foi realizada com base em um estudo de caso envolvendo análise de porosidade de amostras de solos agrícolas, os quais apresentam caminhos preferenciais para o fluxo de água e solutos (fingering). Resultados ilustram a verificação consistente dos caminhos preferenciais das amostras de solos agrícolas, analisadas com base no ambiente desenvolvido.
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Ärleryd, Sebastian. "Realtime Virtual 3D Image of Kidney Using Pre-Operative CT Image for Geometry and Realtime US-Image for Tracking." Thesis, Uppsala universitet, Avdelningen för visuell information och interaktion, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-234991.
Повний текст джерелаАнотація:
In this thesis a method is presented to provide a 3D visualization of the human kidney and surrounding tissue during kidney surgery. The method takes advantage of the high detail of 3D X-Ray Computed Tomography (CT) and the high time resolution of Ultrasonography (US). By extracting the geometry from a single preoperative CT scan and animating the kidney by tracking its position in real time US images, a 3D visualization of the surgical volume can be created. The first part of the project consisted of building an imaging phantom as a simplified model of the human body around the kidney. It consists of three parts: the shell part representing surrounding tissue, the kidney part representing the kidney soft tissue and a kidney stone part embedded in the kidney part. The shell and soft tissue kidney parts was cast with a mixture of the synthetic polymer Polyvinyl Alchohol (PVA) and water. The kidney stone part was cast with epoxy glue. All three parts where designed to look like human tissue in CT and US images. The method is a pipeline of stages that starts with acquiring the CT image as a 3D matrix of intensity values. This matrix is then segmented, resulting in separate polygonal 3D models for the three phantom parts. A scan of the model is then performed using US, producing a sequence of US images. A computer program extracts easily recognizable image feature points from the images in the sequence. Knowing the spatial position and orientation of a new US image in which these features can be found again allows the position of the kidney to be calculated. The presented method is realized as a proof of concept implementation of the pipeline. The implementation displays an interactive visualization where the kidney is positioned according to a user-selected US image scanned for image features. Using the proof of concept implementation as a guide, the accuracy of the proposed method is estimated to be bounded by the acquired image data. For high resolution CT and US images, the accuracy can be in the order of a few millimeters.
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Martins, Marcelo Tarcísio. "Avaliação das reformatações de arquivos DICOM, originados de tomografia computadorizada de feixe cônico, para planejamento cirúrgico virtual em implantodontia." Universidade Federal de Juiz de Fora, 2012. https://repositorio.ufjf.br/jspui/handle/ufjf/1697.
Повний текст джерелаАнотація:
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FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais
Métodos de planejamento cirúrgico baseado em imagens de tomografia computadorizada de feixe cônico são utilizados para aprimorar a terapêutica em Implantodontia. Esta tecnologia possibilita a manipulação das imagens pelo Cirurgião-Dentista. Para isto, é necessário que a imagem enviada pela clínica de radiologia tenha sido reformatada/convertida, para um programa de planejamento cirúrgico virtual; necessário para tornar o exame compatível com a capacidade de processamento dos computadores domésticos. O objetivo desta pesquisa foi comparar a nitidez e a medida da altura de 55 exames tomográficos em um corte coronal da região mandibular posterior inferior entre os arquivos DICOM reformatados em 3 (3X-RF) e 5 vezes (5X-RF) e o não reformatado (S-RF). Em valores absolutos o grupo S-RF apresentou imagens mais nítidas que os demais. Foi significativa a análise da variância das fontes de variação, inerentes ao processo de medição (p≤0,05). Pelo Estudo de Gage R&R concluiu-se que os critérios de medições da altura do lado direito (MID) e do lado esquerdo (MIE), não foram alterados nos grupos S-RF, 3X-RF e 5X-RF.
Methods of surgical planning based on images from cone beam computed tomography are used to improve therapy in Implantology. This technology allows the manipulation of images by the Dental Surgeon. For this, it is necessary that the image sent for clinical radiology has been resized / converted to a program of virtual surgical planning, necessary to make the examination compatible with the processing power of home computers. The aim of this study was to compare the sharpness and height measurement of coronal section of the mandibular posterior region in 55 CT scans between DICOM files reformatted in 3 (RF-3X) and 5 (RF-5X) times, and not reformatted (S-RF). The S-RF group showed sharper images than the RF-3X and 5X-RF groups. The variance analysis of the sources of variation inherent in the measurement process was statistically significant between groups (p ≤ 0.05). By Gage R & R study concluded that measures of height of coronal mandibular right and left, did not differ in groups S-RF, RF-3X and 5X-RF.
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Jover, Jérémy. "Contribution à la réduction des pertes d'informations dans l'industrie du bois : utilisation de la Résonance Quadrupolaire Nucléaire pour l'identification de marqueurs chimiques et de la virtualisation du processus de production pour la détermination de nomenclatures divergentes." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0239/document.
Повний текст джерелаАнотація:
La conservation des informations dans les industries dont le processus de transformation est divergent à toujours posé d'important contraintes, et l'industrie du bois n'y manque pas. Les solutions de traçabilité existantes à l'heure actuelle ne permettent pas de conserver ces informations tout au long du cycle de vie du produit bois. L'objectif de cette thèse est de montrer la faisabilité de deux concepts permettant d'améliorer la conservation de l'information : le paradigme de matière communicante et le paradigme de Virtual Manufacturing. Avec le premier paradigme, il est possible de conserver les informations relatives à l'origine du produit grâce à un marquage chimique introduit dans l'ensemble de la matière que nous identifions par Résonance Quadrupolaire Nucléaire. Dans le deuxième paradigme pour anticipons les caractéristiques biométriques des produits finaux en numérisant la matière et en virtualisant les opérations de transformation. Grâce à cela, il est possible de déterminer, malgré l'imperfection des données et des décisions les caractéristiques des produitsInformation conservation in the divergent process has always imposed important constraints. In the Wood industry, in which the problem is present, has no solution to conserve information all along the wood life cycle. This thesis goal is to validate the use of two new paradigms allowing improving the information conservation: the communicating material and the virtual manufacturing. With the first one, the wood material is intrinsically marked with chemical product which can be identify with the Nuclear Quadrupole Resonance and allow conserving the material origin. With the second one, it is possible to anticipate sawmill production by foresee the final product characteristics
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Ibrahim, Idris. "A virtual instrument tomographic measurement system." Thesis, Manchester Metropolitan University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485325.
Повний текст джерелаАнотація:
Increasing applications of Pe's in industry has led to the concept of the Virtual Instrument (VI), allowing greater flexibility and ease of modification for different situations, making Virtual Instrumentation increasingly favourable over traditional standalone instruments. This thesis provides insight into the uses of VI techniques for tomographic imaging, using proprietary hardware and software, applied to a pneumatic polypropylene transportation system. The VI based tomographic imaging system is used as part of a flow control mechanism and is used for mass-flow measurement and analysis. The thesis presents an introduction to Electrical Capacitance Tomography and its applications for process monitoring in particular, for use with the MMU flow rig, which emulates the pneumatic conveyance of solids for ~ typical industrial system. An argument for the selection of Virtual Instrumentati~n for tomographic imaging is . presented and the benefits and limitations discussed. An overview of tomographic imaging is presented, from basic electrical field concepts and their associated' data normalisations techniques for the generation of permittivity images to various reconstruction methods. Details -of proprietary and application specific hardware is given, two distinct ECT imaging systems using the AC-bridge capacitance detection technique have been developed. An 8-electrode serial capacitance data acquisition system and a higher performance 8/12-electrode parallel data acquisition system. Both ECT imaging systems utilise a National Instruments based PXI instrumentation platform and LabVIE\y graphical programming environment. A discussion on the implementation of the software developed for both ECT systems, highlighting some of the software optimisation strategies employed and an evaluation of the ECT systems is presented. The performance of each tomographic system in terms of image accuracy and speed and the differences between an 8electrode and a higher resolution 12-electrode imaging system is analysed. The applications of the VI based tomographic imaging systems are discussed, both the serial and parallel 8-electrode being successfully applied to flow control using Artificial Neural Networks. The dual-plane imaging capability of the parallel system has allowed accurate measurement of terminal velocities for vertical pellet flow and is used for mass-flow measurement using cross-correlation. A Virtual Instrument, incorporating a Tomographic system capable of imaging pneumatically conveyed pellets in the MMU flow rig, has been designed and built using LabVIEW software running on an embedded Pentium-4 PXI controller. This has resulted in a system which is independent of the standard PC platform and is a robust system, capable of use in an industrial environment. Advantages of using the PXI system include having an imaging system that uses proprietary interchangeable hardware, that can be easily modified. In addition it lends itself to a platform that can be used for developing powerful tools using LabVIEW and Matlab. The VI Measurement System VIMS has shown distinct advantages for applications where fast frame rates are not critical but design flexibility and low development costs are required.
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Rositi, Hugo. "Approche informationnelle de l’imagerie de contraste de phase par rayonnement synchrotron : Applications précliniques à l’imagerie du cerveau du petit animal." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0094/document.
Повний текст джерелаАнотація:
L’histologie virtuelle est un domaine qui suscite un intérêt de recherche croissant. Nous nous intéressons à une de ces techniques en particulier via l’imagerie de contraste de phase par rayonnement synchrotron. Cette imagerie nous permet d’observer des cerveaux de souris intacts avec une résolution spatiale de 8µm isotropique, soit une résolution similaire à celle d’une histologie optique classique mais sans endommager les tissus par des colorations ou des marquages spécifiques. Ces travaux de thèse sont organisés autour de trois grands axes. Un premier axe présente l’instrumentation photonique qui permet l’obtention du contraste de phase et le paramétrage original qui est proposé pour l’acquisition d’échantillons biologiques de composition hétérogène. Un second axe présente différents traitements d’images développés pour des tâches informationnelles précises telles que l’optimisation de la visualisation, la détection d’agrégats cellulaires et la tractographie de structures fibreuses. Enfin, une application biomédicale de ces traitements est proposée via la détection et la quantification de nanoparticules d’oxyde de fer dans un modèle expérimental d’accident vasculaire cérébralVirtual histology is a field of investigation with growing interest in the commmunity of bioimage analysis. We focus on one of these techniques with the phase contrast tomography using synchrotron radiation. This technique allows us to visualize mice brains with no impact and with a spatial resolution of 8µm isotropically, which is a resolution similar to the one obtained with classic optical histology but without damaging samples with specific dyeing. This thesis is organized along three main axes. The first one presents photonic instrumentation which gives us access to the phase information and the original setting of a reconstruction parameter for the acquisition of biological heterogeneous samples. A second axis shows several image processing developed in order to address different informational tasks such as visual optimization, cellular aggregates detection or fiber tractography. Eventually, a biomedical application of these process is proposed by adressing detection and quantification of iron oxide nanoparticles in an experimental model of stroke
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Falcão, João Luiz de Alencar Araripe. "Comparação das dimensões das artérias coronárias e da composição da placa aterosclerótica entre a angiografia coronária por tomografia de 64 colunas de detectores e a ultrassonografia intracoronária com a técnica de histologia virtual." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/5/5131/tde-11052010-133735/.
Повний текст джерелаАнотація:
Introdução: No momento, pouco se conhece sobre o desempenho diagnóstico da angiotomografia de coronárias com 64 colunas de detectores (Angio-TC 64) frente aos achados do ultrassom intracoronário com técnica de histologia virtual (USIC-HV). Este estudo compara a capacidade diagnóstica de ambos os métodos para a avaliação das dimensões vasculares e para avaliação da composição da placa aterosclerótica através da análise de toda extensão dos três vasos epicárdicos principais. Métodos e Resultados: Um total de 21 pacientes com diagnóstico de doença arterial coronária obstrutiva foi incluído neste estudo. Angio-TC 64 foi realizada em todos os pacientes antes da realização do USIC-HV, com intervalo<72horas entre os dois exames. No total, 70 vasos foram avaliados (3,3 vasos por paciente) e divididos em 641 subsegmentos de 4 mm de extensão cada. Um total de 5.972 cortes seccionais de USIC-HV e 5.233 cortes seccionais da Angio-TC 64 foram analisados. As medidas de área luminar, área do vaso, área da parede arterial e carga de placa à Angio-TC 64 e ao USIC-HV foram significativamente correlacionadas (r-Spearman: 0,81; 0,78; 0,55 e 0,49; respectivamente - p<0,001 para todas as correlações). A Angio-TC 64 subestimou a área luminar ao USIC-HV (em mediana: 0,4mm2 ,variando entre -5,6 mm2 e 10,2 mm2). A Angio-TC 64 superestimou a área do vaso, a área da parede arterial (placa+média) e a carga de placa (em mediana: 3,0 mm2; 3,2 mm2 e 13,9%, respectivamente). O aumento da densidade média da placa à Angio-TC 64 foi significativamente associado com o aumento da contribuição percentual dos componentes cálcio denso e núcleo necrótico ao USIC-HV. O aumento da densidade média da placa à Angio-TC 64 foi significativamente associado com a diminuição da contribuição percentual do componente fibro-lipídico ao USIC-HV. Parâmetros de qualidade da imagem (atenuação luminar, ruído da atenuação luminar e relação sinal ruído) influenciaram significativamente os resultados da Angio-TC 64. Conclusão: Nosso estudo demonstra que as imagens da Angio-TC 64 se correlacionam significativamente com as imagens do USIC-HV. Estes achados indicam que a Angio-TC 64 pode ser uma ferramenta útil para a avaliação quantitativa da luz arterial e da placa aterosclerótica; bem como para a avaliação da composição da placa aterosclerótica in vivoBackground: Currently, little is known about the comparative diagnostic performance for coronary assessment of 64-slice multidetector computed tomography (64-MDCT) versus virtual histology intravascular ultrasound technique (VH-IVUS). The present study compares the diagnostic ability of both methods for the evaluation of coronary lumen and vessel wall dimensions as well as plaque composition in a three-vessel whole-artery analysis protocol. Methods and Results: A total of 21 patients with diagnosed obstructive coronary artery disease was included. 64-MDCT was performed within 72 hours before the VH-IVUS examination. Overall, 70 vessels were imaged (3.3 vessels per patient), and divided into 641 subsegments of 4 mm each. A total of 5,972 VH-IVUS cross-sections and 5,233 64-MDCT cross-sections were analyzed. 64-MDCT and VH-IVUS measurements for luminar area, vessel area, arterial wall area (plaque plus media area) and plaque burden were significantly correlated (r-Spearman: 0.81; 0.78; 0.55 e 0.49; respectively - p<0,001 for all correlations). 64-MDCT underestimated VH-IVUS measurements for luminar area (median: 0.4mm2, range: -5.6 mm2 to 10,2 mm2). 64-MDCT overestimated VH-IVUS measurements for vessel area, arterial wall area, and plaque burden (median: 3.0 mm2; 3.2 mm2 e 13.9%, respectively). Increasing plaque density at 64-MDCT was significantly associated with increasing dense calcium and necrotic core percent composition at VH-IVUS. Increasing plaque density at 64-MDCT was significantly associated with decreasing fibrofatty percent composition, and decreasing necrosis-to-calcium ratio at VH-IVUS. Image quality parameters (i.e. lumen attenuation, image noise, signal-to-noise ratio) significantly influenced the results of 64-MDCT. Conclusion: Our study shows that 64-MDCT imaging significantly correlates with VH-IVUS. These findings indicate that 64-MDCT may be a useful non-invasive tool for quantitative evaluation of lumen and plaque parameters, as well as for the in vivo assessment of atherosclerotic plaque composition
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Pires, Sandrerley Ramos. "Interpolação tridimensional de imagens de tomografia computadorizada utilizando equações diferenciais parciais." Universidade Federal de Uberlândia, 2007. https://repositorio.ufu.br/handle/123456789/14640.
Повний текст джерелаАнотація:
The visualization of a 3D image obtained from computerized tomography examinations has shown itself to be an important factor for increasing the quality of medical
diagnoses and, consequently, treatment efficacy. There already exist on the market, several visualization softwares, which use different techniques to show the 3D tomography
image. However, to show a high quality 3D image, sophisticated devices must be used
to obtain slices, close to one another, thus increasing the incidence of X-ray given to the
patient. An interpolation slice method which resulted from the TC examination produces
good results, and is able to reduce the X-ray incidence upon the patient. This method
must reconstruct the curvature from the patient s internal structures without using slices
in close proximity. This work proposes a method of 3D image interpolation, composed
of a juxtaposition of the slices from CT examination results. The goal of this method is
to increase the quality of 3D visualization through the production of sharp and precise
structure contours. This thesis proposes the division of the interpolation method into two
steps. In the first step, the goal is to obtain an initial representation of the image in 3D,
which is composed of real slices as well as virtual slices which are referred to in this work
as initial virtual slices. In the second step, the empty spaces of the structure are recovered
by the 3D image inpainting process. This work also proposes a method to obtain the initial virtual slice and two different methods for inpainting the 3D image. These inpainting
methods are the transversal slice line prolongation method and the transportation and
diffusion of information. Both methods use the differential equation theory. The transportation and diffusion of information method shows better results than other methods
proposed in this work, besides this, this method presents better results than the linear
interpolation and Goshtasby et al. [1] methods also implemented in this work. Visual and
numerical comparisons are used to obtain this conclusion. The numerical measures used
are statistical correlation, the PSNR and the Hausdorff distance [2]. The transportation
and diffusion of information method shows itself able to produce better results than all
the other tested methods. Besides this principal contribution, this work also developed a
KIT to implement 2D and 3D CT visualize applications.A visualização de imagens resultantes de exame de tomografia computadorizada (TC) em 3D ´e um fator importante para o aumento da precisão nos diagnósticos médicos e, consequentemente, na eficácia dos tratamentos. Atualmente existem diversos produtos no mercado, que fazem uso de várias técnicas existentes para apresentação de imagens tomográficas em 3D. Contudo, para se obter maior suavidade e precisão nos contornos das estruturas visualizadas em 3D, utiliza-se equipamentos capazes de produzir fatias paralelas do corpo humano muito próximas uma das outras, aumentando a exposição dos pacientes aos raios X. Um método de interpolação de fatias resultantes de exame de TC que forneça bons resultados, pode reduzir a incidência de raios X no paciente, pois esse método pode recuperar a curvatura das estruturas sem a necessidade de uma grande proximidade entre as fatias. Este trabalho propõe um método para a interpolação de imagem em 3D, formada pela justaposição de fatias de resultados de exames de tomografia computadorizada. O objetivo desse método ´e obter contornos suaves e precisos, melhorando os processos de visualização em 3D. Para isso, esta tese propõe a divisão do processo de interpolação em duas etapas. Na primeira etapa obtém-se uma representação inicial da imagem em 3D composta por fatias reais e por fatias denominadas de fatias virtuais iniciais e, na segunda etapa, restaura-se essas estruturas geradas com um processo de retoque de imagem em 3D. Este trabalho propõe também um método para obtenção da fatia virtual inicial e dois métodos diferentes para a realização do passo de retoque da imagem em 3D resultante da justaposição das fatias reais e virtuais iniciais. Esses métodos são o prolongamento de linhas nas fatias transversais e transporte e difusão de informações. Ambos os métodos utilizam a teoria de equações diferenciais. O método de transporte e difusão de informações demonstrou melhores resultados do que outro método proposto neste trabalho, além de obter melhores resultados do que os métodos de interpolação linear e Goshtasby e outros [1] implementados neste trabalho. Comparações visuais e comparações numéricas utilizando a correlação estatística, a PSNR e a distância de Haussdorff [2] foram realizadas para se obter essas conclusões. O método de transporte e difusão de informações é capaz de gerar contornos mais suaves e precisos que esses outros métodos testados. Além dessa contribuição principal, este trabalho também desenvolveu um KIT para a construção de aplicações visualizadoras de tomografias computadorizadas em 2D e em 3D.
Mestre em Ciências
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Yanikian, Fabio. "Comparação em meio digital entre os eixos transversais horizontais mandibulares definidos anatomicamente e por axiografia." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/23/23151/tde-22092016-150926/.
Повний текст джерелаАнотація:
O objetivo deste estudo foi comparar o eixo de rotação verdadeiro com o anatômico em ambiente virtual 3D, e seus efeitos sobre dois pontos anatômicos mandibulares. O eixo verdadeiro foi determinado em 14 indivíduos por meio de axiografia, e transferido para o ambiente virtual por TCFC, e posteriormente determinado anatomicamente, onde foram medidas as distâncias entre ambos. Foram simuladas rotações de 2º, 5º e 8º da mandíbula nos dois eixos, tanto para abertura como fechamento, e quantificadas as diferenças nos pontos da linha média inferior (LMI) e pogônio (Pg). O teste t pareado foi utilizado para examinar as diferenças entre as médias nas posições desses pontos (p<0,05). Os eixos verdadeiros localizaram-se dentro de um raio de 5 mm do anatômico em 67,86% da amostra. A distância absoluta média entre os eixos foi de 4,79 mm, enquanto que a vetorial foi de 2,33 no plano horizontal e 3,03 mm no vertical, resultando na direção anteroinferior em 71,43% dos eixos verdadeiros. Houve diferença estatisticamente significante na posição dos pontos LMI e Pg para todas as magnitudes e direções, entre os eixos. O eixo verdadeiro está localizado na direção anteroinferior em relação ao anatômico. Os efeitos na mandíbula são significantes e diferentes em todas as amplitudes, tanto para abertura como fechamento, porém com possível pequena relevância clínica.The aim of this study was to compare the true hinge axis to the anatomic one in a virtual 3D environment, and also their respective effects on two mandibular anatomic points. The true axis has been determined in 14 individuals by means of axiography, and later transferred to a virtual environment by CBTC, where the anatomical axis was determined, and measured the distances between them. Mandibular rotation of 2º, 5º and 8º in both axes were performed, both for opening and closing, as well as the quantification of the difference found in the points of the lower midline (LM) and pogonion (Pg). Paired t-test was used to examine differences between the average values in the position of those points (p<0,05). The true axis was located within a 5mm-radius of the anatomic axis throughout 67.86% of the sample. The average absolute distance between the axes was 4.79 mm, while the vector distance was 2.33 mm in the horizontal plane e 3.03mm in the vertical plane, amounting to an anteriorinferior direction of 71.43% of the true axis. There was significant difference in the position of points LM and Pg to all magnitudes and directions within the axes. The true hinge axis is located in the anterior-inferior direction in relation to the anatomic axis. The effects observed onto the mandible are significant and different in all amplitudes, both for opening and closing positions, however they present small clinical relevance.
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Ferraz, Eduardo Gomes. "Efeito do processamento de reconstruções tridimensionais virtuais para confecção de biomodelos de prototipagem rápida: estudo experimental em mandíbulas secas humanas." Programa de Pós- Graduação em Odontologia da UFBA, 2009. http://www.repositorio.ufba.br/ri/handle/ri/10538.
Повний текст джерелаАнотація:
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O presente estudo teve como objetivo avaliar a acurácia de reconstruções tridimensionais virtuais de mandíbulas secas humanas, produzidas com diferentes protocolos de segmentação, suavização e refinamento superficial. Para isto foram construídas 80 imagens tridimensionais virtuais, provenientes do exame de tomografia computadorizada de dez mandíbulas secas, nas quais medidas lineares entre pontos anatômicos pré-determinados foram obtidas e comparadas, para uma probabilidade de erro de 5%. Os resultados obtidos demonstraram diferença significativa entre as medidas obtidas nas mandíbulas originais (padrão ouro) quando comparadas com as imagens confeccionadas a partir da segmentação outline (p<0,05) e all boundary (p<0,001) sem as ferramentas de suavização ou refinamento. Já após a utilização das diferentes formas de segmentação associadas às ferramentas de pós-processamento (suavização e refinamento), não houve diferença entre as medidas dos modelos apenas refinados ou apenas suavizados (p>0,05) com as do padrão ouro. Quando estas duas ferramentas foram aplicadas em conjunto, houve diferença estatística, quando comparadas ao padrão ouro, tanto para a segmentação outline (p<0,001), quanto para a all boundary (p<0,001). Foi avaliado também o erro dimensional dos modelos tridimensionais virtuais obtidos pelos diferentes protocolos utilizados no estudo. Esta análise demonstrou que os melhores resultados ocorreram nos modelos apenas suavizados pela segmentação outline (erro de 2,50 mm /6,52%) e os apenas refinados pela segmentação all boundary (erro de 2,37 mm /6,28%), enquanto que as maiores diferenças foram observadas nos modelos construídos sem pós-processamento, com a segmentação outline (erro de 2,50 mm /7,17%) e naqueles com as duas ferramentas de pósprocessamento a partir da segmentação all boundary (erro de 2,85 mm /7,12%). Avaliada ainda a variabilidade intra e inter-examinador constatou-se uma concordância extremamente forte em ambos os casos (p<0,05), o que demonstra a reprodutibilidade do método.
Salvador
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Perchet, Diane. "Modélisation in-silico des voies aériennes : reconstruction morphologique et simulation fonctionnelle." Phd thesis, Université René Descartes - Paris V, 2005. http://tel.archives-ouvertes.fr/tel-00273244.
Повний текст джерелаАнотація:
Dans les nouveaux protocoles thérapeutiques par voie inhalée, le dosage des particules actives reste un problème complexe qui dépend de trois principaux facteurs : leur taille, la dynamique des flux et les variations de calibre bronchique. La solution nécessite de disposer d'un modèle de distribution des gaz et aérosols administrés dans les poumons. Ventilation pulmonaire et effets du cycle respiratoire sur la dynamique des fluides deviennent deux enjeux clés de la pratique clinique.Dans ce contexte, le projet RNTS RMOD a pour objectif de développer un simulateur morpho-fonctionnel des voies respiratoires pour l'aide au diagnostic, au geste médico-chirurgical et à l'administration de médicaments par inhalation.
Contribuant au projet RMOD, la recherche développée dans cette thèse propose une modélisation in-silico de la structure des voies aériennes supérieures (VAS) et proximales (VAP) à partir d'examens tomodensitométriques (TDM). L'investigation morphologique et la simulation fonctionnelle bénéficient alors de géométries 3D réelles, adaptées au patient et spécifiques des pathologies rencontrées.
La modélisation développée fait coopérer des méthodes originales de segmentation, de construction de surface maillée et d'analyse morpho-fonctionnelle.
La segmentation des VAP est obtenue par un schéma diffusif et agrégatif gouverné par un modèle markovien, dont l'initialisation repose sur l'opérateur de coût de connexion sous contrainte topographique. De cette segmentation, l'axe central de l'arbre bronchique est extrait de manière robuste et précise en combinant information de distance, propagation de fronts, et partition conditionnelle locale. Cet axe central est représenté sous forme d'une structure hiérarchique multivaluée synthétisant caractéristiques topologiques et géométriques de l'arbre bronchique. Une surface maillée est ensuite construite en appliquant une procédure de Marching Cubes adaptative, les paramètres des différents filtres mis en jeu étant automatiquement ajustés aux caractéristiques locales du réseau bronchique conditionnellement aux attributs de l'axe central.
La segmentation des VAS repose sur une propagation markovienne exploitant les variations locales de densité. L'initialisation combine morphologie mathématique et information de contour afin de garantir la robustesse à la topologie. Une procédure de type triangulation de Delaunay restreinte à une surface fournit ensuite la représentation maillée des VAS. Il est établi que la topologie et la géométrie des structures complexes composant les VAS sont effectivement préservées.
Pour permettre aux médecins de valider les modèles maillés ainsi construits, un environnement virtuel 3D convivial et interactif a été réalisé. En outre, la morphologie des voies aériennes exo- et endo-luminale est analysée de façon automatique à partir de simulations d'écoulement pour des géométries réelles.
Enfin, une modélisation unifiée des VAP et VAS est obtenue pour la première fois. Elle démontre la pertinence des approches développées. Elle ouvre la voie à la construction de modèles in-silico complets de l'appareil respiratoire ainsi qu'aux études fonctionnelles prenant en compte les paramètres morphologiques susceptibles d'influer localement ou globalement sur la dynamique des écoulements.
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Jover, Jeremy. "Contribution à la réduction des pertes d'informations dans l'industrie du bois." Phd thesis, Université de Lorraine, 2013. http://tel.archives-ouvertes.fr/tel-00921941.
Повний текст джерелаАнотація:
La conservation des informations dans les industries dont le processus de transformation est divergent a toujours induit d'importantes contraintes, et en particulier dans l'industrie du bois. Les solutions de traçabilité existant à l'heure actuelle ne permettent pas de conserver ces informations tout au long du cycle de vie du produit bois. L'objectif de cette thèse est de montrer la faisabilité de deux concepts contribuant à la conservation de l'information : le paradigme de matière communicante et le paradigme de Virtual Manufacturing. Avec le premier, il est possible de conserver les informations relatives à l'origine du produit par l'intermédiaire d'un marquage chimique appliqué à l'ensemble de la matière, lequel marquage sera identifié par Résonance Quadrupolaire Nucléaire. Dans le deuxième paradigme nous anticipons l'évaluation des caractéristiques des produits finaux en numérisant la matière et en virtualisant les opérations de transformation. Grâce à cela, il est possible de déterminer les caractéristiques des produits réels en prenant en compte l'imperfection des données et des décisions.
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Su, Hong-Jin, and 蘇虹今. "Establishing virtual cardio motion with ten-sequence 3D volume of computed tomography cardiac images." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/7radz9.
Повний текст джерелаАнотація:
碩士中原大學
生物醫學工程研究所
107
According to World Health Organization (WHO), Cardiac diseases have been considered as the world''s second-largest category in elevating mortality with an average of 31% of deaths per year. Therefore, in cardiac studies, it is important to assess the anatomy and functionality first. Clinically, three-dimensional computed tomography (CT) images of the heart are often used for disease diagnosis. However, some diseases can be identified by observing the blood flow and internal structure, but CT images we use today do not have these two functions. In academic research, most of the knowledge can be grasped only through textbooks and online platforms that sometimes cannot be apprehended easily to understand the function and structure of the heart and other organs. We aimed to develop a software that can observe the four-dimensional internal structure and the image of the pulsating state of heart. In this work, we create a dynamic heart image by loading ten-timing 2D CT images of heart, and then display internal and external cardiac structure after removal of heart surrounding organs and color conversion, and then merge the two methods above to form a dynamic internal and external cardiac structure images. The research is divided into two platforms:1) Four-dimensional imaging platform can display dynamic three-dimensional images of different states such as heart blood and internal structure of the heart; 2) Three-dimensional images platform includes functions of changing the color, sharpness, gradient color, and various states conversion. The user can change the functions for image display according to their requirements. An image processing system has been developed successfully utilizing ten-times cardiac images to present internal structures and beating heart images to the platform. In future, our software can be a useful tool for learning and clinical applications.
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Töpperwien, Mareike. "3d virtual histology of neuronal tissue by propagation-based x-ray phase-contrast tomography." Doctoral thesis, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E440-4.
Повний текст джерела
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"Automatic extraction of bronchus and centerline determination from CT images for three dimensional virtual bronchoscopy." 2000. http://library.cuhk.edu.hk/record=b5890498.
Повний текст джерелаАнотація:
Law Tsui Ying.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.
Includes bibliographical references (leaves 64-70).
Abstracts in English and Chinese.
Acknowledgments --- p.ii
Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- Structure of Bronchus --- p.3
Chapter 1.2 --- Existing Systems --- p.4
Chapter 1.2.1 --- Virtual Endoscope System (VES) --- p.4
Chapter 1.2.2 --- Virtual Reality Surgical Simulator --- p.4
Chapter 1.2.3 --- Automated Virtual Colonoscopy (AVC) --- p.5
Chapter 1.2.4 --- QUICKSEE --- p.5
Chapter 1.3 --- Organization of Thesis --- p.6
Chapter 2 --- Three Dimensional Visualization in Medicine --- p.7
Chapter 2.1 --- Acquisition --- p.8
Chapter 2.1.1 --- Computed Tomography --- p.8
Chapter 2.2 --- Resampling --- p.9
Chapter 2.3 --- Segmentation and Classification --- p.9
Chapter 2.3.1 --- Segmentation by Thresholding --- p.10
Chapter 2.3.2 --- Segmentation by Texture Analysis --- p.10
Chapter 2.3.3 --- Segmentation by Region Growing --- p.10
Chapter 2.3.4 --- Segmentation by Edge Detection --- p.11
Chapter 2.4 --- Rendering --- p.12
Chapter 2.5 --- Display --- p.13
Chapter 2.6 --- Hazards of Visualization --- p.13
Chapter 2.6.1 --- Adding Visual Richness and Obscuring Important Detail --- p.14
Chapter 2.6.2 --- Enhancing Details Incorrectly --- p.14
Chapter 2.6.3 --- The Picture is not the Patient --- p.14
Chapter 2.6.4 --- Pictures-'R'-Us --- p.14
Chapter 3 --- Overview of Advanced Segmentation Methodologies --- p.15
Chapter 3.1 --- Mathematical Morphology --- p.15
Chapter 3.2 --- Recursive Region Search --- p.16
Chapter 3.3 --- Active Region Models --- p.17
Chapter 4 --- Overview of Centerline Methodologies --- p.18
Chapter 4.1 --- Thinning Approach --- p.18
Chapter 4.2 --- Volume Growing Approach --- p.21
Chapter 4.3 --- Combination of Mathematical Morphology and Region Growing Schemes --- p.22
Chapter 4.4 --- Simultaneous Borders Identification Approach --- p.23
Chapter 4.5 --- Tracking Approach --- p.24
Chapter 4.6 --- Distance Transform Approach --- p.25
Chapter 5 --- Automated Extraction of Bronchus Area --- p.27
Chapter 5.1 --- Basic Idea --- p.27
Chapter 5.2 --- Outline of the Automated Extraction Algorithm --- p.28
Chapter 5.2.1 --- Selection of a Start Point --- p.28
Chapter 5.2.2 --- Three Dimensional Region Growing Method --- p.29
Chapter 5.2.3 --- Optimization of the Threshold Value --- p.29
Chapter 5.3 --- Retrieval of Start Point Algorithm Using Genetic Algorithm --- p.29
Chapter 5.3.1 --- Introduction to Genetic Algorithm --- p.30
Chapter 5.3.2 --- Problem Modeling --- p.31
Chapter 5.3.3 --- Algorithm for Determining a Start Point --- p.33
Chapter 5.3.4 --- Genetic Operators --- p.33
Chapter 5.4 --- Three Dimensional Painting Algorithm --- p.34
Chapter 5.4.1 --- Outline of the Three Dimensional Painting Algorithm --- p.34
Chapter 5.5 --- Optimization of the Threshold Value --- p.36
Chapter 6 --- Automatic Centerline Determination Algorithm --- p.38
Chapter 6.1 --- Distance Transformations --- p.38
Chapter 6.2 --- End Points Retrieval --- p.41
Chapter 6.3 --- Graph Based Centerline Algorithm --- p.44
Chapter 7 --- Experiments and Discussion --- p.48
Chapter 7.1 --- Experiment of Automated Determination of Bronchus Algorithm --- p.48
Chapter 7.2 --- Experiment of Automatic Centerline Determination Algorithm --- p.54
Chapter 8 --- Conclusion --- p.62
Bibliography --- p.63
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Lee, Cheng-Kang, and 李正綱. "System Integration of Spectral Domain Optical Coherence Tomography with Virtual Detector Laser-scanning Optical Resolution Photoacoustic Microscopy." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/dr8wf7.
Повний текст джерела
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Simard, Mikaël. "Étude de la tomodensitométrie spectrale quantitative et ses applications en radiothérapie." Thesis, 2021. http://hdl.handle.net/1866/25252.
Повний текст джерелаАнотація:
La tomodensitométrie par rayons-X (CT) est une modalité d’imagerie produisant une carte tridimensionnelle du coefficient d’atténuation des rayons-X d’un objet. En radiothérapie, le CT fournit de l’information anatomique et quantitative sur le patient afin de permettre la planification du traitement et le calcul de la dose de radiation à livrer. Le CT a plusieurs problèmes, notamment (1) une limitation au niveau de l’exactitude des paramètres physiques quantitatifs extraits du patient, et (2) une sensibilité aux biais causés par des artéfacts de durcissement du faisceau. Enfin, (3) dans le cas où le CT est fait en présence d’un agent de contraste pour améliorer la planification du traitement, il est nécessaire d’effectuer un deuxième CT sans agent de contraste à des fins de calcul de dose, ce qui augmente la dose au patient. Ces trois problèmes limitent l’efficacité du CT pour certaines modalités de traitement qui sont plus sensibles aux incertitudes comme la protonthérapie.
Le CT spectral regroupe un ensemble de méthodes pour produire plusieurs cartes d’atténuation des rayons-X moyennées sur différentes plages énergétiques. L’information supplémentaire, pondérée en énergie qui est obtenue permet une meilleure caractérisation des matériaux analysés. Le potentiel de l’une de ces modalités spectrales, le CT bi-énergie (DECT), est déjà bien démontré en radiothérapie, alors qu’une approche en plein essor, le CT spectral à comptage de photons (SPCCT), promet davantage d’information spectrale à l’aide de détecteurs discriminateurs en énergie. Par contre, le SPCCT souffre d’un bruit plus important et d’un conditionnement réduit. Cette thèse investigue la question suivante : y a-t-il un bénéfice à utiliser plus d’information résolue en énergie, mais de qualité réduite pour la radiothérapie ? La question est étudiée dans le contexte des trois problèmes ci-haut.
Tout d’abord, un estimateur maximum a posteriori (MAP) est introduit au niveau de la caractérisation des tissus post-reconstruction afin de débruiter les données du CT spectral. L’approche est validée expérimentalement sur un DECT. Le niveau de bruit du pouvoir d’arrêt des protons diminue en moyenne d’un facteur 3.2 à l’aide de l’estimateur MAP. Celui-ci permet également de conserver généralement le caractère quantitatif des paramètres physiques estimés, le pouvoir d’arrêt variant en moyenne de 0.9% par rapport à l’approche conventionnelle. Ensuite, l’estimateur MAP est adapté au contexte de l’imagerie avec agent de contraste. Les résultats numériques démontrent un bénéfice clair à utiliser le SPCCT pour l’imagerie virtuellement sans contraste par rapport au DECT, avec une réduction de l’erreur RMS sur le pouvoir d’arrêt des protons de 2.7 à 1.4%. Troisièmement, les outils développés ci-haut sont validés expérimentalement sur un micro-SPCCT de la compagnie MARS Bioimaging, dont le détecteur à comptage de photons est le Medipix 3, qui est utilisé pour le suivi de particules au CERN. De légers bénéfices au niveau de l’estimation des propriétés physiques à l’aide du SPCCT par rapport au DECT sont obtenus pour des matériaux substituts à des tissus humains. Finalement, une nouvelle paramétrisation du coefficient d’atténuation pour l’imagerie pré-reconstruction est proposée, dans le but ultime de corriger les artéfacts de durcissement du faisceau. La paramétrisation proposée élimine les biais au niveau de l’exactitude de la caractérisation des tissus humains par rapport aux paramétrisations existantes. Cependant, aucun avantage n’a été obtenu à l’aide du SPCCT par rapport au DECT, ce qui suggère qu’il est nécessaire d’incorporer l’estimation MAP dans l’imagerie pré-reconstruction via une approche de reconstruction itérative.X-ray computed tomography (CT) is an imaging modality that produces a tridimensional map of the attenuation of X-rays by the scanned object. In radiation therapy, CT provides anatomical and quantitative information on the patient that is required for treatment planning. However, CT has some issues, notably (1) a limited accuracy in the estimation of quantitative physical parameters of the patient, and (2) a sensitivity to biases caused by beam hardening artifacts. Finally, (3) in the case where contrast-enhanced CT is performed to help treatment planning, a second scan with no contrast agent is required for dose calculation purposes, which increases the overall dose to the patient. Those 3 problems limit the efficiency of CT for some treatment modalities more sensitive to uncertainties, such as proton therapy. Spectral CT regroups a set of methods that allows the production of multiple X-ray attenuation maps evaluated over various energy windows. The additional energy-weighted information that is obtained allows better material characterization. The potential of one spectral CT modality, dual-energy CT (DECT), is already well demonstrated for radiation therapy, while an upcoming method, spectral photon counting CT (SPCCT), promises more spectral information with the help of energy discriminating detectors. Unfortunately, SPCCT suffers from increased noise and poor conditioning. This thesis thus investigates the following question: is there a benefit to using more, but lower quality energy-resolved information for radiotherapy? The question is studied in the context of the three problems discussed earlier. First, a maximum a posteriori (MAP) estimator is introduced for post-reconstruction tissue characterization for denoising purposes in spectral CT. The estimator is validated experimentally using a commercial DECT. The noise level on the proton stopping power is reduced, on average, by a factor of 3.2 with the MAP estimator. The estimator also generally con- serves the quantitative accuracy of estimated physical parameters. For instance, the stopping power varies on average by 0.9% with respect to the conventional approach. Then, the MAP estimation framework is adapted to the context of contrast-enhanced imaging. Numerical results show clear benefits when using SPCCT for virtual non-contrast imaging compared to DECT, with a reduction of the RMS error on the proton stopping power from 2.7 to 1.4%. Third, the developed tools are validated experimentally on a micro-SPCCT from MARS Bioimaging, which uses the Medipix 3 chip as a photon counting detector. Small benefits in the accuracy of physical parameters of tissue substitutes materials are obtained. Finally, a new parametrization of the attenuation coefficient for pre-reconstruction imaging is pro- posed, whose ultimate aim is to correct beam hardening artifacts. In a simulation study, the proposed parametrization eliminates all biases in the estimated physical parameters of human tissues, which is an improvement upon existing parametrizations. However, no ad- vantage has been obtained with SPCCT compared to DECT, which suggests the need to incorporate MAP estimation in the pre-reconstruction framework using an iterative reconstruction approach.
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Lapointe, Andréanne. "Applications du tomodensitomètre à double énergie en radio-oncologie." Thèse, 2018. http://hdl.handle.net/1866/20604.
Повний текст джерела