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Quantitative evaluation of a pulmonary contour segmentation algorithm in x-ray computed tomography images1

Santos, Beatriz Sousa; Ferreira, Carlos; Silva, José Silvestre; Silva, Augusto; Teixeira, Luísa
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
Relevância na Pesquisa
75.97%
Pulmonary contour extraction from thoracic x-ray computed tomography images is a mandatory preprocessing step in many automated or semiautomated analysis tasks. This study was conducted to quantitatively assess the performance of a method for pulmonary contour extraction and region identification.Materials and methods; http://www.sciencedirect.com/science/article/B75BK-4CYP37B-8/1/cd6c2e81a2efebfbc072409358fc238a

Classificando fraturas do rádio com raio-X e tomografia; Classifying radius fractures with X-ray and tomography imaging

YUNES FILHO, Paulo Roberto Miziara; PEREIRA FILHO, Miguel Viana; GOMES, Fabiano Cortese Paula; MEDEIROS, Rodrigo Serikawa de; PAULA, Emygdio José Leomil de; MATTAR JUNIOR, Rames; ZUMIOTTI, Arnaldo Valdir
Fonte: Atha Comunicação & Editora Publicador: Atha Comunicação & Editora
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
66.07%
INTRODUÇÃO: Este estudo avaliou a confiabilidade interobservador da radiografia simples versus tomografia computadorizada para as classificações Universal e AO em fraturas do rádio distal. PACIENTES e MÉTODOS: Cinco observadores classificaram 21 fraturas do rádio distal utilizando radiografias e tomografias independentemente. O índice Kappa foi utilizado para estabelecer o nível de concordância entre os observadores. RESULTADOS: A confiabilidade interobservador da classificação Universal foi moderada e a confiabilidade interobservador da classificação AO foi baixa. Reduzindo a clas-sificação AO a nove categorias e às três categorias básicas houve melhora do nível de confiabilidade para "moderado". Não houve diferença entre a confiabilidade interobservador da classificação Universal baseada em imagens radiográficas em comparação com a classificação Universal baseada em imagens tomográficas. A confiabilidade interobservador da classificação AO baseada em radiografias simples foi significativamente maior que a confiabilidade interobservador da classificação AO baseada apenas em tomografias computadorizadas. CONCLUSÃO: A partir destes dados, concluímos que classificar fraturas do rádio distal utilizando tomografias computadorizadas sem o auxílio das radiografias simples não traz benefício.; INTRODUCTION: This study evaluated the interobserver reliability of plain radiograpy versus computed tomography (CT) for the Universal and AO classification systems for distal radius fractures. PATIENTS AND METHODS: Five observers classified 21 sets of distal radius fractures using plain radiographs and CT independently. Kappa statistics were used to establish a relative level of agreement between observers for both readings. RESULTS: Interobserver agreement was rated as moderate for the Universal classification and poor for the AO classification. Reducing the AO system to 9 categories and to its three main types reliability was raised to a "moderate" level. No difference was found for interobserver reliability between the Universal classification using plain radiographs and the Universal classification using computed tomography. Interobserver reliability of the AO classification system using plain radiographs was significantly higher than the interobserver reliability of the AO classification system using only computed tomography. CONCLUSION: From these data...

CLASSIFYING RADIUS FRACTURES WITH X-RAY AND TOMOGRAPHY IMAGING

YUNES FILHO, Paulo Roberto Miziara; PEREIRA FILHO, Miguel Viana; GOMES, Fabiano Cortese Paula; MEDEIROS, Rodrigo Serikawa De; PAULA, Emygdio Jose Leomil de; MATTAR JUNIOR, Rames; ZUMIOTTI, Arnaldo Valdir
Fonte: ATHA COMUNICACAO & EDITORA Publicador: ATHA COMUNICACAO & EDITORA
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.06%
Introduction: This study evaluated the interobserver reliability of plain radiograpy versus computed tomography (CT) for the Universal and AO classification systems for distal radius fractures. Patients and methods: Five observers classified 21 sets of distal radius fractures using plain radiographs and CT independently. Kappa statistics were used to establish a relative level of agreement between observers for both readings. Results: Interobserver agreement was rated as moderate for the Universal classification and poor for the AO classification. Reducing the AO system to 9 categories and to its three main types reliability was raised to a ""moderate"" level. No difference was found for interobserver reliability between the Universal classification using plain radiographs and the Universal classification using computed tomography. Interobserver reliability of the AO classification system using plain radiographs was significantly higher than the interobserver reliability of the AO classification system using only computed tomography. Conclusion: From these data, we conclude that classification of distal radius fractures using CT scanning without plain radiographs is not beneficial.

Avaliação do reparo tecidual em defeito ósseo por microtomografia tridimensional por raio X; Evaluation of tissue repair after bone fracture using 3D X-ray microtomography

Introini, Simone Orlandi
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 01/07/2011 PT
Relevância na Pesquisa
75.88%
A fratura é uma descontinuidade óssea que pode ser produzida cirurgicamente ou causada por um impacto que excede a resistência mecânica do osso dando início a uma sequência de eventos sistêmicos e específicos de resposta do tecido. Exames radiológicos são comumente realizados na clínica e em experimentos com animais para o monitoramento do reparo ósseo dando informações sobre o alinhamento dos fragmentos e da evolução de reparo. Outras técnicas de monitoramento qualitativas e quantitativas podem ser utilizadas em experimento animal (histologia e ensaios mecânicos) e em experimento animal e clínico (tomografia computadorizada por raio X, ressonância magnética, ultra-sonografia). A microtomografia 3D por raio X é uma nova técnica de monitoramento para uso em experimento animal e com grande potencialidade. A quantificação do reparo ósseo com novas metodologias tem larga aplicação em investigações sobre técnicas invasivas e não-invasivas de tratamento de fraturas utilizando-se experimento animal. O objetivo dessa investigação foi a utilização da microtomografia 3D por raio X policromático ('mü'CT) para a avaliação do reparo ósseo em defeito ósseo na tíbia direita de rato macho da raça Wistar com peso aproximado de 280 g. O defeito foi produzido por uma broca odontológica com alta rotação. Foram estabelecidos quatro grupos experimentais caracterizados pela utilização ou não utilização do tratamento do defeito por ultra-som pulsado de baixa intensidade (LIPUS...

Tomografia computadorizada de raios-X aplicada à análise da qualidade ambiental de solo no entorno da Usina Hidrelétrica de Ilha Solteira - SP ; X-ray computed tomography applied to the analysis of the environmental quality of soil at usina hidrelétrica de Ilha Solteira (SP)

Tseng, Chien Ling
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/02/2013 PT
Relevância na Pesquisa
76.03%
O processo de recuperação das terras degradadas pela pecuária, principalmente no Brasil, tornou-se uma solução incontestável para atender à necessidade alimentar não somente do país, mas também mundial. Com o fim de avaliar a qualidade física de recuperação de áreas degradadas, propõe-se neste trabalho, aplicar o método de Tomografia Computadorizada de Raios-X (T.C.), mais precisamente o uso de um microtomógrafo não médico. As amostras de solo foram coletadas no entorno da Usina Hidrelétrica de Ilha Solteira (SP) e pastagens do MS. Foram selecionados seis tratamentos de solo para a aplicação de procedimentos técnicos: um ocupado por vegetação nativa (Cerrado), um de pastagem recuperada, um de pastagem degradada, outro de solo tratato com Astronium fraxinifolium (Gonçalo-alves) + Brachiaria decumbens + Lodo de esgoto, um de solo degradado/decapitado e um último de solo recuperado. Inicialmente, foi feito um estudo básico sobre os fundamentos da Física do Solo, o método de Tomografia Computadorizada e as técnicas de recuperação de solo. Em seguida foram obtidas as imagems tomográficas por meio de microtomógrafo e de software NRCon, pertencentes à Embrapa Instrumentação e à Faculdade de Odontologia da Unesp - Araraquara. Assim...

Construction and test of low cost X-ray tomography scanner for physical-chemical analysis and nondestructive inspections

De Oliveira Jr., José Martins; Martins, Antonio César Germano
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Conferência ou Objeto de Conferência Formato: 102-105
ENG
Relevância na Pesquisa
85.98%
X-ray computed tomography (CT) refers to the cross-sectional imaging of an object measuring the transmitted radiation at different directions. In this work, we describe the development of a low cost micro-CT X-ray scanner that is being developed for nondestructive testing. This tomograph operates using a microfocus X-ray source and contains a silicon photodiode as detectors. The performance of the system, by its spatial resolution, has been estimated through its Modulation Transfer Function - MTF and the obtained value at 10% of MTF is 661 μm. It was built as a general purpose nondestructive testing device. © 2009 American Institute of Physics.

Determinação dos parâmetros de convecção- dispersão- transferência de massa em meio poroso usando tomografia computadorizada; Determination of convection- dispersion- mass transfer parameters in porous media using computed tomography

Janeth Alina Vidal Vargas
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 20/02/2015 PT
Relevância na Pesquisa
76.01%
O conhecimento dos fenômenos físicos envolvidos no transporte de fluidos no meio poroso é muito importante para o projeto e o sucesso dos processos de recuperação melhorada de petróleo. O deslocamento miscível é um dos métodos mais eficientes de recuperação melhorada de petróleo. O parâmetro mais relevante na eficiência do deslocamento miscível é a dispersão, que controla a evolução da zona de mistura dos dois fluidos e a propagação do fluido injetado. Neste trabalho é desenvolvido e avaliado um modelo matemático para o deslocamento miscível 1-D em meios heterogêneos. O modelo, referido como modelo de concentração total (MCT) é desenvolvido com base na equação de convecção-dispersão (ECD) considerando a interação entre a rocha e os fluidos. Os parâmetros fenomenológicos envolvidos no MCT são o coeficiente de dispersão, o coeficiente de transferência de massa, a porosidade efetiva do meio poroso no momento de deslocamento e a fração de soluto que é depositada ou retirada do meio poroso. Estes parâmetros podem ser determinados por meio de ajustes multiparâmétricos do modelo aos dados obtidos em laboratório. Para avaliar a aplicação do modelo MCT foram realizados dois experimentos A e B...

Application of x-ray computed tomography in the evaluation of soil porosity in soil management systems

Beraldo,José M. G.; Scannavino Junior,Francisco de A.; Cruvinel,Paulo E.
Fonte: Associação Brasileira de Engenharia Agrícola Publicador: Associação Brasileira de Engenharia Agrícola
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2014 EN
Relevância na Pesquisa
75.95%
The study aimed to evaluate a methodology to quantify the porosity of the soil using computed tomography in areas under no-tillage, conventional tillage and native forest. Three soil management systems were selected for the study: forest, conventional tillage and no-tillage. In each soil management system, undisturbed soil samples were collected in the surface layer (0.0 to 0.10 m). The tomographic images were obtained using a X-ray microtomography. After obtaining the images, they were processed, and a methodology was evaluated for image conversion into numerical values. The statistical method which provided the greatest accuracy was the percentile method. The methodology used to analyze the tomographic image allowed quantifying the porosity of the soil under different soil management. The method enabled the characterization of soil porosity in a non-evasive and non-destructive way.

Clinical versus computed tomography evaluation in the diagnosis and management of deep neck infection

Crespo,Agricio Nubiato; Chone,Carlos Takahiro; Fonseca,Adriano Santana; Montenegro,Maria Carolina; Pereira,Rodrigo; Milani,João Altemani
Fonte: Associação Paulista de Medicina - APM Publicador: Associação Paulista de Medicina - APM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2004 EN
Relevância na Pesquisa
66.11%
CONTEXT: Deep neck infections have high potential for severe complications and even death, if not properly managed. The difference between clinical and computed tomography findings may demonstrate that clinical evaluation alone underestimates disease extent, which may lead to conservative treatment with worse prognosis. OBJECTIVE: To compare clinical and computed tomography findings from neck spaces affected by deep neck infections and to determine the main clinical and radiological features associated with these. TYPE OF STUDY: Non-randomized retrospective study. SETTING: Department of Otolaryngology and Head and Neck, Universidade Estadual de Campinas. METHODS: Medical charts of 65 patients with deep neck infections were evaluated. Age, gender, clinical complaints, physical findings, computed tomography scan and x-ray imaging, microbiology, treatment and outcome were analyzed. All clinical signs and symptoms were evaluated and stratified in order of frequency. The frequency of neck space involvement in such infections was also assessed from the clinical and tomographic evaluation. All clinical and computed tomography findings were compared with surgical observation. RESULTS: The most frequent clinical findings were neck swelling...

Effects of X-Ray Dose On Rhizosphere Studies Using X-Ray Computed Tomography

Zappala, Susan; Helliwell, Jonathan R.; Tracy, Saoirse R.; Mairhofer, Stefan; Sturrock, Craig J.; Pridmore, Tony; Bennett, Malcolm; Mooney, Sacha J.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 26/06/2013 EN
Relevância na Pesquisa
66.07%
X-ray Computed Tomography (CT) is a non-destructive imaging technique originally designed for diagnostic medicine, which was adopted for rhizosphere and soil science applications in the early 1980s. X-ray CT enables researchers to simultaneously visualise and quantify the heterogeneous soil matrix of mineral grains, organic matter, air-filled pores and water-filled pores. Additionally, X-ray CT allows visualisation of plant roots in situ without the need for traditional invasive methods such as root washing. However, one routinely unreported aspect of X-ray CT is the potential effect of X-ray dose on the soil-borne microorganisms and plants in rhizosphere investigations. Here we aimed to i) highlight the need for more consistent reporting of X-ray CT parameters for dose to sample, ii) to provide an overview of previously reported impacts of X-rays on soil microorganisms and plant roots and iii) present new data investigating the response of plant roots and microbial communities to X-ray exposure. Fewer than 5% of the 126 publications included in the literature review contained sufficient information to calculate dose and only 2.4% of the publications explicitly state an estimate of dose received by each sample. We conducted a study involving rice roots growing in soil...

X-ray CT investigations of intact soil cores with and without living crop roots

McNeill, A.; Kolesik, P.
Fonte: The Regional Institute Ltd; CD-ROM Publicador: The Regional Institute Ltd; CD-ROM
Tipo: Conference paper
Publicado em //2004 EN
Relevância na Pesquisa
75.95%
X-ray computed tomography (CT) was used to non-destructively visualise intact cores of soil (15 cm diameter and 50 cm depth) collected from a farming region in South Australia. The texture contrast soil comprised 20-30 cm of nutrient poor sand over dense sodic clay. Cores were taken from a non-ripped paddock and from an adjacent paddock that had been ‘deep ripped’ to 50 cm. Image-reconstruction software was used to visualise in three dimensions (3D) macro-morphological features of the soil cores. Canola was grown in some of the cores and several times during plant development the cores were scanned. Roots visualised were of a diameter equal or larger than 1 mm and the volume, surface area, length and position of these ‘exploratory’ roots was quantified. At the end of the experiment destructive root sampling and two-dimensional (2D) scanning were used to measure the total length and volume of all roots. The work revealed the architecture and morphology of root systems in situ and tracked response to soil macro-structures such as layers of organic matter in the sand, the clay domes at the interface with the sand, old root channels, calcium deposits, stones, and areas of soil that were naturally more loose. Root penetration was much slower in cores from the non-ripped paddock than in cores from the ripped paddock...

The X-factor: visualizing undisturbed root architecture in soils using X-ray computed tomography

Tracy, S.; Roberts, J.; Black, C.; McNeill, A.; Davidson, R.; Mooney, S.
Fonte: Oxford Univ Press Publicador: Oxford Univ Press
Tipo: Artigo de Revista Científica
Publicado em //2010 EN
Relevância na Pesquisa
75.92%
Saoirse R. Tracy, Jeremy A. Roberts, Colin R. Black, Ann McNeill, Rob Davidson and Sacha J. Mooney

Imaging of Membrane Electrode Assemblies of Proton Exchange Membrane Fuel Cells by X-Ray Computed Tomography

PFRANG Andreas; VEYRET Damien; JANSSEN Gaby; TSOTRIDIS Georgios
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Contributions to Conferences Formato: Printed
ENG
Relevância na Pesquisa
66.06%
X-ray computed tomography was applied for the 3D imaging of membrane electrode assemblies (MEAs) together with two attached gas diffusion layers. These samples were investigated as prepared and after voltage cycling. It was possible to achieve sub-µm resolution using a lab-based stand-alone tomography system as well as a tomography add-on for a scanning electron microscope. The carbon fibres of the gas diffusion layers could be clearly resolved and the catalyst layers could be visualized. X-ray computed tomography data was also used for the validation of results from scanning electron microscopy of cross sections of membrane electrode assemblies where the sample is exposed to significant mechanical loads during sample preparation. More specifically, it was shown that the cracks observed in catalyst layers by scanning electron microscopy already exist in the membrane electrode assembly as prepared and are not a result of sample preparation. Finally it was shown that the crack density in the catalyst layers does not significantly change during voltage cycling which suggests that crack formation is not a principal cause of the observed performance decay of the MEA; JRC.DDG.F.2-Cleaner energy

Software architecture for multi-bed FDK-based reconstruction in X-ray CT scanners

Abella, Mónica; Vaquero, Juan José; Sisniega, Alejandro; Pascau, Javier; Udías, Ángel; García, V.; Vidal-Migallón, I.; Desco, Manuel
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/acceptedVersion; info:eu-repo/semantics/article Formato: application/pdf
Publicado em /08/2012 ENG
Relevância na Pesquisa
85.98%
Most small-animal X-ray computed tomography (CT) scanners are based on cone-beam geometry with a flat-panel detector orbiting in a circular trajectory. Image reconstruction in these systems is usually performed by approximate methods based on the algorithm proposed by Feldkamp et al. (FDK). Besides the implementation of the reconstruction algorithm itself, in order to design a real system it is necessary to take into account numerous issues so as to obtain the best quality images from the acquired data. This work presents a comprehensive, novel software architecture for small-animal CT scanners based on cone-beam geometry with circular scanning trajectory. The proposed architecture covers all the steps from the system calibration to the volume reconstruction and conversion into Hounsfield units. It includes an efficient implementation of an FDK-based reconstruction algorithm that takes advantage of system symmetries and allows for parallel reconstruction using a multiprocessor computer. Strategies for calibration and artifact correction are discussed to justify the strategies adopted. New procedures for multi-bed misalignment, beam-hardening, and Housfield units calibration are proposed. Experiments with phantoms and real data showed the suitability of the proposed software architecture for an X-ray small animal CT based on cone-beam geometry.; This work was partially funded by AMIT project from the CDTI CENIT program...

Exploiting parallelism in a X-ray tomography reconstruction algorithm on hybrid multi-GPU and multi-core platforms

Liria, Ernesto; Higuero, Daniel; Abella, Mónica; Molina, Claudia de; Desco, Manuel
Fonte: Ieee - The Institute Of Electrical And Electronics Engineers, Inc Publicador: Ieee - The Institute Of Electrical And Electronics Engineers, Inc
Tipo: info:eu-repo/semantics/acceptedVersion; info:eu-repo/semantics/conferenceObject; info:eu-repo/semantics/bookPart
Publicado em //2012 ENG
Relevância na Pesquisa
75.92%
Most small-animal X-ray computed tomography (CT) scanners are based on cone-beam geometry with a flat-panel detector orbiting in a circular trajectory. Image reconstruction in these systems is usually performed by approximate methods based on the algorithm proposed by Feldkamp et al. Currently there are a strong need to speed-up the reconstruction of XRay CT data in order to extend its clinical applications. We present an efficient modular implementation of an FDK-based reconstruction algorithm that takes advantage of the parallel computing capabilities and the efficient bilinear interpolation provided by general purpose graphic processing units (GPGPU). The proposed implementation of the algorithm is evaluated for a high-resolution micro-CT and achieves a speed-up of 46, while preserving the reconstructed image quali; This work has been partially funded by AMIT Project CDTI CENIT, TEC2007-64731, TEC2008-06715-C02-01, RD07/0014/2009, TRA2009 0175, RECAVA-RETIC, RD09/0077/00087 (Ministerio de Ciencia e Innovacion), ARTEMIS S2009/DPI-1802 (Comunidad de Madrid), and TIN2010-16497 (Ministerio de Ciencia e Innovacion).; Proceedings of: 2012 10 th IEEE International Symposium on Parallel and Distributes Processing with Applicatioons (ISPA 2012). Leganés...

COMPUTED TOMOGRAPHY FOR THE NON-DESTRUCTIVE IMAGING OF CULTURAL HERITAGE: X-RAY, GAMMA AND NEUTRON SOURCES

NGUYEN, HAI-YEN
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
66.12%
X-ray and neutron computed tomography (CT) have been used successfully for the non-destructive imaging of artifact in art conservation. These applications range from object investigations to the use of micro-focus CT for experimental studies. While there is precedent for the use of CT in art conservation, the method is still limited in application partially due to restricted access to facilities and the high cost of producing publishable results. The purpose of this study was to identify alternative CT methods including the use of different radiation sources and industrial imaging system. Both investigations of the use of low-flux neutron CT at the Royal Military College in Kingston compared to high-flux neutron CT at the Advanced Neutron Tomography And Radiography Experimental System (ANTARES) at FRM-II in Garching, Munich and the use of megavoltage gamma ray computed tomography at Kingston General Hospital in Kingston successfully imaged the corroded metal artifacts. The artifacts investigated were from the Diniacopoulos Collection at Queen’s University and were underwater concretions of L’Anse aux Bouleaux provided by Parks Canada. This study also evaluated the Xradia XCT-400 for comparison to similar systems used in conservation. This evaluation also provided successful images of corroded metal coins from the Diniacopoulos Collection for use in identification. To address the issue of cost prohibitive image analysis programs...

3D chemical imaging in the laboratory by hyperspectral X-ray computed tomography

Egan, C. K.; Jacques, S. D. M.; Wilson, M. D.; Veale, M. C.; Seller, P.; Beale, A. M.; Pattrick, R. A. D.; Withers, P. J.; Cernik, R. J.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 30/10/2015 EN
Relevância na Pesquisa
66.06%
We report the development of laboratory based hyperspectral X-ray computed tomography which allows the internal elemental chemistry of an object to be reconstructed and visualised in three dimensions. The method employs a spectroscopic X-ray imaging detector with sufficient energy resolution to distinguish individual elemental absorption edges. Elemental distributions can then be made by K-edge subtraction, or alternatively by voxel-wise spectral fitting to give relative atomic concentrations. We demonstrate its application to two material systems: studying the distribution of catalyst material on porous substrates for industrial scale chemical processing; and mapping of minerals and inclusion phases inside a mineralised ore sample. The method makes use of a standard laboratory X-ray source with measurement times similar to that required for conventional computed tomography.

Strategies for Temporal and Spectral Imaging with X-ray Computed Tomography

Johnston, Samuel Morris
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2012
Relevância na Pesquisa
75.81%

X-ray micro-CT is widely used for small animal imaging in preclinical studies of cardiopulmonary disease, but further development is needed to improve spatial resolution, temporal resolution, and material contrast. This study presents a set of tools that achieve these improvements. These tools include the mathematical formulation and computational implementation of algorithms for calibration, image reconstruction, and image analysis with our custom micro-CT system. These tools are tested in simulations and in experiments with live animals. With these tools, it is possible to visualize the distribution of a contrast agent throughout the body of a mouse as it changes over time, and produce 5-dimensional images (3 spatial dimensions + time + energy) of the cardiac cycle.

; Dissertation

Practical lessons learnt from the application of X-ray computed tomography to evaluate the internal structure of asphalt mixtures

Alvarez-Lugo,Allex Eduardo; Carvajal-Muñoz,Juan Sebastián
Fonte: DYNA Publicador: DYNA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2014 EN
Relevância na Pesquisa
96.1%
X-ray Computed Tomography (X-ray CT) has allowed for the efficient non-destructive characterization of the internal structure of paving asphalt mixtures (AM), and has led to multiple practical lessons learnt based on the analysis of laboratory- and field-produced AM. This paper aims at summarizing these practical lessons, to facilitate their future application and further developments, in terms of: (i) fabrication of laboratory specimens, (ii) comparison of laboratory- and field-compacted mixtures, (iii) comparison of hot-mix asphalt and warm-mix asphalt mixtures, (iv) effects of additives, temperature, and compaction, (v) stone-on-stone contact, (vi) relationship between internal structure and performance, and (vii) modeling applications. These practical lessons are primarily gathered from the analysis of the air void distribution of laboratory-and field-produced AM, evaluated through X-ray CT, which has led to relevant inputs for the assessment of the response and performance of AM. X-ray CT enables computation of the AM internal structure with multiple practical applications and future opportunities to enhance the microstructure of AM and, consequently, optimize their performance.

Air void characterisation of HMA gyratory laboratory-moulded samples and field cores using X-ray computed tomography (X-ray CT)

Walubita,L F; Jamison,B; Alvarez,A E; Hu,X; Mushota,C
Fonte: Journal of the South African Institution of Civil Engineering Publicador: Journal of the South African Institution of Civil Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2012 EN
Relevância na Pesquisa
106.11%
The research work presented in this paper deals with the characterisation of the internal structure of hot-mix asphalt (HMA), incorporating both gyratory compacted samples produced in the laboratory and field cores. The primary objective was to determine the optimum trim depth on either end of laboratory-moulded HMA cylindrical samples that would optimise the air void (AV) uniformity in the test specimens. The analysis was based on the X-ray Computed Tomography (X-ray CT) scanning tests and subsequent image analyses. Two Texas HMA mixes, namely a coarse-graded (Type B) and a fine-graded (Type D) mix, with gyratory samples compacted in the laboratory to two different heights (110 and 164 mm) were evaluated for their internal structure in terms of the distribution of both the AV content and AV size. Analysis of the results indicated that the coarse-graded HMA mix (Type B) and the taller (164 mm in height) gyratory-moulded samples would be more likely associated with a more heterogeneous distribution of the AV content and AV size, respectively. Supplemented with field cores, the X-ray CT results indicated significantly poor AV content distribution (i.e. higher AV content and weakest area) at the ends, particularly in the top and bottom 20 mm zone of the samples. Thus...