Dissertations / Theses on the topic 'Virtual tomography'
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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.
Full textАврунін, 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.
Full textNicolson, Heather Johan. "Exploring the Earth's subsurface with virtual seismic sources and receivers." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5726.
Full textMalusek, 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.
Full textKang, 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/.
Full textThe 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.
Chouika, Nabil. "Generalized Parton Distributions and their covariant extension : towards nucleon tomography." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS259/document.
Full textGeneralized 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
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.
Full textSchanandore, 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.
Full textRosa, 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/.
Full textObjective: 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.
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.
Full textFreitas, 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/.
Full textPurpose: 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.
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.
Full textEste 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.
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.
Full textThis 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.
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.
Full textMartins, 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.
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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.
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.
Full textInformation 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
Ibrahim, Idris. "A virtual instrument tomographic measurement system." Thesis, Manchester Metropolitan University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485325.
Full textRositi, 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.
Full textVirtual 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
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/.
Full textBackground: 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
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.
Full textA 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
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/.
Full textThe 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.
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.
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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
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.
Full textDans 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.
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.
Full textSu, 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.
Full text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.
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.
Full text"Automatic extraction of bronchus and centerline determination from CT images for three dimensional virtual bronchoscopy." 2000. http://library.cuhk.edu.hk/record=b5890498.
Full textThesis (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
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.
Full textSimard, Mikaël. "Étude de la tomodensitométrie spectrale quantitative et ses applications en radiothérapie." Thesis, 2021. http://hdl.handle.net/1866/25252.
Full textX-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.
Lapointe, Andréanne. "Applications du tomodensitomètre à double énergie en radio-oncologie." Thèse, 2018. http://hdl.handle.net/1866/20604.
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