Página 1 dos resultados de 8014 itens digitais encontrados em 0.002 segundos

Dynamic texture analysis and segmentation using deterministic partially self-avoiding walks
Gonçalves, Wesley Nunes; Bruno, Odemir Martinez
Fonte: Elsevier; Amsterdam Publicador: Elsevier; Amsterdam
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
361.1114%
#Dynamic texture#Dynamic texture recognition#Deterministic partially self-avoiding walks#RECONHECIMENTO DE PADRÕES#PROCESSAMENTO DE IMAGENS
Dynamic texture is a recent field of investigation that has received growing attention from computer vision community in the last years. These patterns are moving texture in which the concept of selfsimilarity for static textures is extended to the spatiotemporal domain. In this paper, we propose a novel approach for dynamic texture representation, that can be used for both texture analysis and segmentation. In this method, deterministic partially self-avoiding walks are performed in three orthogonal planes of the video in order to combine appearance and motion features. We validate our method on three applications of dynamic texture that present interesting challenges: recognition, clustering and segmentation. Experimental results on these applications indicate that the proposed method improves the dynamic texture representation compared to the state of the art.; FAPESP (10/08614-0, 11/01523-1); CNPq (308449/2010-0, 473893/2010-0)

Texture analysis and classification: a complex network-based approach
Backes, André Ricardo; Casanova, Dalcimar; Bruno, Odemir Martinez
Fonte: Elsevier; Philadelphia Publicador: Elsevier; Philadelphia
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
360.22574%
#Texture analysis#Texture recognition#Complex network#REDES COMPLEXAS#TEXTURA (ANÁLISE)
In this paper, we propose a novel texture analysis method using the complex network theory. We investigated how a texture image can be effectively represented, characterized and analyzed in terms of a complex network. The proposed approach uses degree measurements to compose a set of texture descriptors. The results show that the method is very robust, and it presents a excellent texture discrimination for all considered classes, overcoming traditional texture methods.; CNPq (308449/2010-0, 473893/2010-0); FAPESP (11/01523-1, 06/54367-9, 08/57313-2)

Texture profile and correlation between sensory and instrumental analyses on extruded snacks
Paula, Amanda Maldo; Conti-Silva, Ana Carolina
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 9-14
ENG
Relevância na Pesquisa
360.22574%
#Descriptive analysis#Instrumental analysis#Snack food#Texture#Different shapes#Extruded snacks#Good correlations#Instrumental texture analysis#Texture profile#Hardness#Instruments
Instrumental texture analysis on extruded snacks is widely applied, however there is no scientific consensus about the test and probe types that can be correlated with the sensory texture of snacks. Eleven commercial extruded snacks of different shapes were evaluated instrumentally using different probes and sensorially through descriptive analysis. The snack texture was described using the attributes of hardness, crispness, adhesiveness, fracturability and chewiness. Cylindrical snacks were described through crispness and fracturability, pelleted and shell-shaped snacks by chewiness and ring-shaped snacks by adhesiveness and hardness. Hardness and adhesiveness were correlated with a Warner-Bratzler test using a V shape probe (r = 0.718 and r = 0.763, respectively), while fracturability and chewiness were correlated with a Warner-Bratzler test using a guillotine (r = 0.776 and r = 0.662, respectively). The fairly strong good correlations enable application of these instrumental tests as an indication of the sensory texture of extruded snacks. © 2013 Elsevier Ltd. All rights reserved.

Analise da arquitetura da aorta de pacientes hipertensos e normotensos; Texture analysis of the elastic fibers in aortas of normotensive and hypertensive patients
Gislaine Vieira
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 20/07/2009 PT
Relevância na Pesquisa
361.83895%
#Textura#Fibras elasticas#Aorta#Texture#Fibers elastic#Aorta
Fibras elásticas são componentes essenciais da aorta e remodelamento é acompanhado em muitas doenças e eventos que ameaçam a vida, como dissecção e rupturas. Fibras elásticas podem ser facilmente visualizadas quando coradas com H&E e examinadas por microscopia de fluorescência. Nosso objetivo foi criar um sistema de análise automática da textura das fibras elásticas comparando aorta de pacientes normotensos e hipertensos. O sistema de análise foi composto por Microscópio invertido Olympus IX-81 equipado com scanner FV 300 que utiliza laser FV-5 COMB2, utilizando laser de argônio a 488 nm, objetiva 40x usando óleo de imersão. A espessura da aorta varia de 2 a 3 mm, e a imagem completa foi composta por justaposição de imagens de 220x220 µm utilizando software Fluoview. Para análise foi utilizado o programa gliding box , que é uma caixa deslizadora de 128x128 pixels, que percorre a imagem da aorta pixel a pixel em toda sua extensão. Para análise computadorizada da textura foram utilizados programas computacionais (entropia, homogeneidade local e segundo momento angular derivado da matriz de co-ocorrência de Haralick). Foram calculados e plotados em diagramas resultados equivalentes à topografia histológica da imagem. Em cada caminho o gliding box percorreu entre 2000 e 3000 pixels da textura...

Analysis of the functional quality of pavements from texture measurements
Freitas, Elisabete F.; Pereira, Paulo A. A.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em //2007 ENG
Relevância na Pesquisa
361.83895%
#Pavement#Profile#Texture ranges#Texture spectrum#Texture level#Indicator#Mean profile depth#IRI
The surface texture of a pavement, including uneveness, is largely determinant of drivers’safety and comfort. It is undoubtedly a major cause of road traffic accidents all over the world. Statistics show that one million killed and 50 million injured are reported every year by Competent Authorities. The effect of traffic noise has also become a critical public issue. On the road networking the surface characteristics of pavements also contributed to nearly 80-90% of roadway traffic noise. Not only engines or exhaust systems generate noise. The impact of tire-surface at speeds above 50 km/h also needs to be added to prime offenders. Functional requirements such as roadway safety, environmental quality, driving comfort and operating costs in the road network are assessed by indicators whose limits are continuously adjusted. The roadway texture is again a main intervenient. This paper aims at describing the texture indicators that can be used for the assessment of the texture of a pavement from a network point of view, based on profiles acquired at high speeds, including megatexture. First an overview of the concepts related to texture and the effects of texture, including unevenness, on safety, driving comfort, ride quality and environmental quality is given. Then...

Analysis of test methods for texture depth evaluation applied in Portugal
Freitas, Elisabete F.; Pereira, Paulo A. A.; Antunes, M. L.; Domingos, P.
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /11/2008 ENG
Relevância na Pesquisa
362.9633%
#Texture#Evaluation#Mean profile depth#Mean texture depth#Sensor measured texture depth
Texture is a surface characteristic which has a very wide influence on pavements functional quality. It is currently assessed by a number of test methods. Road Administrations face the problems of dealing with data acquired by different methods and, in addition to that, the repeatability and reproducibility of the results. This paper presents an analysis of test methods used for texture depth evaluation in Portugal: the volumetric patch method and two methods based on surface profiles. Hence, three roads with low (dense asphalt), medium (“open texture asphalt”) and high (porous asphalt) texture depths were selected, where five profilometers made five runs. Two subsections of 150 m length were also selected to carry out the volumetric patch test. The texture indicators analysed were: the mean texture depth, the mean profile depth and the sensor measured texture depth. The average and the standard deviation were the statistical parameters used for the analysis. The results obtained for each method are significantly different and a good correlation between the mean profile depth and the sensor measured texture depth was established.

3D Surface Profile Equipment for the Characterization of the Pavement Texture - TexScan
Vilaça, João L.; Fonseca, Jaime C.; Pinho, A. C. Marques de; Freitas, Elisabete F.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 08/07/2010 ENG
Relevância na Pesquisa
360.22574%
#Non-contact acquisition#3D reconstruction#Pavement texture characterization#Estimated texture depth#Texture profile level
Loads from vehicles alter the functional and structural characteristics of road pavements that directly affect the loss of resistance of the pavement and the users’ comfort and safety. Those alterations require constant observation and analysis of an extensive area of road surface with high precision. For such it was developed a new scanning prototype machine capable of acquiring the 3D road surface data and characterize the road texture through two algorithms that allows calculate the Estimated Texture Depth (ETD) and Texture Profile Level (L) indicators. The experimental results obtained from nine road samples validate the developed algorithms for the texture analysis and showed good agreement between the scanning prototype equipment and the traditional Sand Patch Method.; Fundação para a Ciência e a Tecnologia (FCT) through the PhD Grant referenced SFRH/ BD/18155/2004

Wireless capsule endoscopic frame classification scheme based on higher order statistics of multi-scale texture descriptors
Barbosa, Daniel; Ramos, Jaime; Lima, C. S.
Fonte: Springer Publicador: Springer
Tipo: Conferência ou Objeto de Conferência
Publicado em //2009 ENG
Relevância na Pesquisa
363.40668%
#Multi-scale texture descriptors#Capsule Endoscopy#Higher Order Statistics#Small bowel disease#Computer aided diagnosis#Discrete wavelet transform#Texture analysis
The gastrointestinal (GI) tract is a long tube, prone to all kind of lesions. The traditional endoscopic methods do not reach the entire GI tract. Wireless capsule endoscopy is a diagnostic procedure that allows the visualization of the whole GI tract, acquiring video frames, at a rate of two frames per second, while travels through the GI tract, propelled by peristalsis. These frames possess rich information about the condition of the stomach and intestine mucosa, expressed by color and texture in these images. These vital characteristics of each frame can be extracted by color texture analysis. Since texture information is present as middle and high frequency content in the original image, two new images are synthesized from the discrete wavelet coefficients at the lowest and middle scale of a two level Discrete Wavelet Transform of the original frame. These new synthesized images contain essential texture information, at different scales, which can be extracted from statistical descriptors of the coocurrence matrices, which are second-order representations of the synthesized images that encode color and spatial relationships within the pixels of these new images. Since the human perception of texture is complex, a multi-scale and multicolor process based in the analysis of the spatial color variations relationships...

Influence of drying on the texture of solar dried pears.
Marques, Bruno; Guiné, Raquel; Cunha, Pedro; Silva, Lizete; Lima, Maria João; Ferreira, Dulcineia
Fonte: Instituto Politécnico de Viseu Publicador: Instituto Politécnico de Viseu
Tipo: Conferência ou Objeto de Conferência
Publicado em //2010 ENG
Relevância na Pesquisa
361.83895%
#pear#drying#Texture#Solar drying
Texture is the result of complex interactions among food components, and the changes in texture occurring during the processing of plant materials or certain physiological events have been related to tissue and cell microstructural changes [1]. The texture parameter, together with appearance and flavour, are the organoleptic quality attributes which determine the acceptability of a food by the consumer. Hence, there has been a great interest in the development of methods to predict and control the texture of plant-based foods, particularly in relation to processing treatments. Instrumental texture profile analysis (TPA) is one of the methods to determine the texture by simulating or imitating the repeated biting or chewing of a food. The pears used in the present study are of the Portuguese variety S. Bartolomeu, which is traditionally dried, and they were dried peeled but uncut. However, unlike in the traditional method the pears were not dried under open-air sun exposure, and, alternatively, were dried in two different systems: solar stove with forced convection (STFC) and solar stove with natural convection (STNC). The drying was carried out until the pears reached a desirable moisture content of about 20 % (wet basis). Before drying...

Texture analysis of computed tomography images of acute ischemic stroke patients
Oliveira,M.S.; Fernandes,P.T.; Avelar,W.M.; Santos,S.L.M.; Castellano,G.; Li,L.M.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2009 EN
Relevância na Pesquisa
360.22574%
#Texture analysis#Computed tomography#Thrombolysis#Discriminant analysis
Computed tomography (CT) images are routinely used to assess ischemic brain stroke in the acute phase. They can provide important clues about whether to treat the patient by thrombolysis with tissue plasminogen activator. However, in the acute phase, the lesions may be difficult to detect in the images using standard visual analysis. The objective of the present study was to determine if texture analysis techniques applied to CT images of stroke patients could differentiate between normal tissue and affected areas that usually go unperceived under visual analysis. We performed a pilot study in which texture analysis, based on the gray level co-occurrence matrix, was applied to the CT brain images of 5 patients and of 5 control subjects and the results were compared by discriminant analysis. Thirteen regions of interest, regarding areas that may be potentially affected by ischemic stroke, were selected for calculation of texture parameters. All regions of interest for all subjects were classified as lesional or non-lesional tissue by an expert neuroradiologist. Visual assessment of the discriminant analysis graphs showed differences in the values of texture parameters between patients and controls, and also between texture parameters for lesional and non-lesional tissue of the patients. This suggests that texture analysis can indeed be a useful tool to help neurologists in the early assessment of ischemic stroke and quantification of the extent of the affected areas.

Filters, Random Fields and Maximum Entropy (FRAME): Towards a Unified Theory for Texture Modeling
Zhu, Song Chun; Wu, Yingnian; Mumford, David Bryant
Fonte: Springer Verlag Publicador: Springer Verlag
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
364.12926%
#texture modeling#texture analysis and synthesis#minimax entropy#maximum entropy#Markov random field#feature pursuit#visual learning
This article presents a statistical theory for texture modeling. This theory combines filtering theory and Markov random field modeling through the maximum entropy principle, and interprets and clarifies many previous concepts and methods for texture analysis and synthesis from a unified point of view. Our theory characterizes the ensemble of images (I) with the same texture appearance by a probability distribution (f(I)) on a random field, and the objective of texture modeling is to make inference about (f(I)), given a set of observed texture examples. In our theory, texture modeling consists of two steps. (1) A set of filters is selected from a general filter bank to capture features of the texture, these filters are applied to observed texture images, and the histograms of the filtered images are extracted. These histograms are estimates of the marginal distributions of (f(I)). This step is called feature extraction. (2) The maximum entropy principle is employed to derive a distribution (p(I)), which is restricted to have the same marginal distributions as those in (1). This (p(I)) is considered as an estimate of (f(I)) . This step is called feature fusion. A stepwise algorithm is proposed to choose filters from a general filter bank. The resulting model...

Mini-texture Tiling
Nagai, Yoshinori; Maddess, Ted
Fonte: Kokushikan University Publicador: Kokushikan University
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
362.4472%
#texture#rule-dynamics#isotrigon#isodipole
Any texture composed of dots or pixels can be reorganized by tiling with small texture patches, or mini-textures. Here we investigate mini-texture properties for constructing any type of texture, and mini-texture relationships of deterministic textures generated by recursive application of rules through gliders such as the so called Box, Cross Zigzag, Oblong, El Wye and Corners gliders, to reveal that the mini-texture tiling recovers isotrigon textures by appropriate selection of tiling. We also consider the concept of a mini-texture basis to implement the rule-dynamics mini-texture tiling for reconstructing the original texture.; yes

Texture Evolution and Variant Selection in Zr-2.5Nb During the α-β Phase Transformation
MOSBRUCKER, PAULA L.
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
362.4472%
#Texture#Variant selection#Zirconium#Phase Transformation
Zr-2.5Nb is used as the pressure tube material for 2nd and 3rd generation CANDU reactors. The physical properties of pressure tubes in service, including strength, dimensional stability, and delayed hydride cracking resistance, are largely dependent upon the crystallographic texture of the hcp α-phase, whose texture is predominantly developed during the extrusion stage of manufacturing. During extrusion and subsequent cooling, the formation of α may occur by transformation of the bcc β-phase to α according to the Burgers relationship and influenced by variant selection – that is, a preference for one or more of the twelve possible orientations of the hcp lattice relative to the bcc lattice. Variant selection has been observed in other Zr alloys, including the heat-treated zone in pressure tube welds and the bulk texture of heat-treated pressure tubes. Further, it has been proposed as a possible explanation for texture characteristics in pressure tubes that are not explained by the deformation mechanics of extrusion. However, the criteria for variant selection are unclear. In this work, an understanding of the criteria for variant selection is developed through observations of the differing mechanisms at play during both directions of transformation...

Applicabilité de la texture couleur à la différentiation des classes d’occupation du territoire sur des images satellitales multispectrales
Boyer, André
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
FR
Relevância na Pesquisa
366.20402%
#Texture couleur#Color texture#Matrices de co-occurrences#Co-occurrences matrix#Classification de l’occupation du sol#Landcover classification#Imagerie multispectrale#Multispectral imaging#Signature texturale#Textural signature#Earth Sciences - Remote Sensing / Sciences de la Terre - Télédétection (UMI : 0799)
La texture est un élément clé pour l’interprétation des images de télédétection à fine résolution spatiale. L’intégration de l’information texturale dans un processus de classification automatisée des images se fait habituellement via des images de texture, souvent créées par le calcul de matrices de co-occurrences (MCO) des niveaux de gris. Une MCO est un histogramme des fréquences d’occurrence des paires de valeurs de pixels présentes dans les fenêtres locales, associées à tous les pixels de l’image utilisée; une paire de pixels étant définie selon un pas et une orientation donnés. Les MCO permettent le calcul de plus d’une dizaine de paramètres décrivant, de diverses manières, la distribution des fréquences, créant ainsi autant d’images texturales distinctes. L’approche de mesure des textures par MCO a été appliquée principalement sur des images de télédétection monochromes (ex. images panchromatiques, images radar monofréquence et monopolarisation). En imagerie multispectrale, une unique bande spectrale, parmi celles disponibles, est habituellement choisie pour générer des images de texture. La question que nous avons posée dans cette recherche concerne justement cette utilisation restreinte de l’information texturale dans le cas des images multispectrales. En fait...

Análise de textura em imagens cerebrais : aplicações em acidente vascular cerebral isquêmico, epilepsia mioclônica juvenil, doença de Machado-Joseph, déficit cognitivo leve e doença de Alzheimer; Texture analysis in brain images : applications in ischemic brain stroke, juvenile myoclonic epilepsy, Machado-Joseph disease, mild cognitive impairment and Alzheimer¿s disease
Márcia Silva de Oliveira
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/06/2010 PT
Relevância na Pesquisa
361.1114%
#Análise de textura em imagens#Tomografia computadorizada#Ressonância magnética#Acidente vascular isquêmico#Epilepsia mioclônica juvenil#Machado-Joseph#Doença de#Alzheimer#Doença de#Deficit cognitivo leve#Processamento de imagens
Análise de textura em imagens digitais é um termo que se refere a um grupo de técnicas de processamento de imagens que objetivam a extração de descritores da imagem ou de regiões de interesse (ROIs) de forma a simplificar a caracterização das mesmas. A textura pode ser entendida como características intrínsecas da imagem (por exemplo: brilho, cor e distribuição de formas) que remetem à ideia de regularidade, rugosidade, suavidade, entre outras, por isso o nome `textura'. Um tipo particular de análise de textura, bastante utilizado em imagens médicas, se baseia em medidas estatítsticas relativas à distribuição de níveis de cinza da imagem (matriz de coocorrência). Os descritores de textura, baseados na matriz de coocorrência, são conhecidos como descritores de Haralick. Este trabalho consistiu na aplicação de vídeo deste tipo de análise em imagens de Tomografia Computadorizada (TC) de vítimas de Acidente Vascular Cerebral Isquêmico e em imagens de Ressonância Magnetica (RM) de portadores de Epilepsia Mioclônica Juvenil, Doença de Machado-Joseph, Déficit Cognitivo Leve e Doença de Alzheimer, visando o desenvolvimento de uma ferramenta computacional que auxilie o neurologista na identificação de areas atingidas por estas doenças e que não sejam distinguíveis em uma análise visual. Neste trabalho foram selecionadas regiões de interesse (ROIs) e calculados os parâmetros de textura para cada grupo de imagens. Após o cálculo dos descritores de textura foi realizada uma análise estatística para verificar se havia diferenciação entre os vários tipos de tecidos. Os resultados obtidos mostraram que a análise de textura pode...

Classificação de imagens digitais por textura usando redes neurais; Classification of di gital images through texture with the aid of neural networks
Liberman, Felipe
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
361.1114%
#Image processing#Computação gráfica#Texture#Processamento : Imagem#Coocurrence matrix#Redes neurais#Inteligência artificial#Neural networks#Backpropagation network
Este trabalho apresenta um estudo sobre a classificação de imagens digitais através da textura com o auxílio de redes neurais. São utilizadas técnicas e conceitos de duas áreas da Informática: O Processamento de Imagens Digitais e a Inteligência Artificial. São apresentados os principais tópicos de processamento de imagens, as principais aplicações em tarefas industriais, reconhecimento de padrões e manipulação de imagens, os tipos de imagem e os formatos de armazenamento. São destacados os atributos da imagem a textura e sua quantificação através da matriz de concorrência dos níveis de cinza. Também apresenta-se alguns sistemas computacionais disponíveis para processamento de imagens. Na área de Inteligência Artificial, o enfoque é para técnicas computacionais inteligentes, mais especificamente as Redes Neurais. É feita uma breve apresentação da área, incluindo seu histórico e suas principais aplicações. As redes neurais são classificadas quanto ao tipo de treinamento, à regra de aprendizado, à topologia da rede e quanto ao tipo de interconexão dos neurônios. O modelo BPN (BackPropagation Network) é visto com maior detalhe, visto ser utilizado na implementação do sistema IMASEG (Sistema para Classificação de Imagens) que faz parte desse trabalho. O BPN é descrito quanto ao seu funcionamento...

Quantitative texture analysis applied to the study of preferential orientations in ferroelectric thin films; Aplicación del análisis cuantitativo de la textura al estudio de orientaciones preferentes en láminas delgadas ferroeléctricas
Ricote, J.; Chateigner, D.
Fonte: Sociedad Española de Cerámica y Vidrio Publicador: Sociedad Española de Cerámica y Vidrio
Tipo: Artículo Formato: 229158 bytes; application/pdf
ENG
Relevância na Pesquisa
361.83895%
#Quantitative texture#Preferential orientation#Thin films#Ferroelectrics#Textura cuantitativa#Orientación preferente#Láminas delgadas#Ferroeléctricos
[EN] The occurrence of preferred crystallographic orientations, or texture, is a determinant factor of the behaviour of polar materials, like ferroelectric thin films. This is the reason why numerous works have been focused in the preparation of highly oriented films for pyroelectric sensors and electromechanical applications. Traditionally, preferred orientations were determined by the analysis of the main reflections obtained by X-ray diffraction, which only in some cases are characteristic of the texture of the material. Regardless of the interest of this subject, the quantitative texture analysis of ferroelectric thin films has not been systematically applied. This consists in the measurement of pole figures with a goniometer, and the determination of the orientation distribution function. In this work we summarise briefly the principles of the quantitative texture analysis and we demonstrate its application to the study of different ferroelectric thin films: La and Ca modified lead titanate (PTL and PTC) and lead zirconate titanate (PZT). This method allows the study of the characteristics of the type of texture and the identification of the different components that contribute to the final texture of the material. An indicative value of the texture strength is also obtained for both the ferroelectric film and the substrate layers. This information allows us the study of the process that leads to the orientation in thin films...

Characterization of Gynecological Tumors using Texture Analysis in the Context of an 18F-FDG Adaptive PET Protocol
Nawrocki, Jeff
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Tese de Doutorado
Publicado em //2015
Relevância na Pesquisa
365.82523%
#Medical imaging and radiology#PET#SUV#Texture Analysis#Texture Features#Treatment Assessment#Tumor Response

In radiation oncology, 18F-FDG Positron Emission Tomography (PET) is used for determining metabolic activity of cancers as well as delineating gross tumor volumes (GTV) for treatment planning. More recently, PET is being utilized for adaptive therapies for gynecological malignancies in which tumor response may be estimated and treatments adjusted during the course of radiation. In addition to treatment assessment, 18F-FDG PET has become a tool in the prediction of tumor response because of the derived Standard Uptake Value (SUV), a measure of the metabolic activity of a tumor. In this study, we seek to establish texture analysis as complimentary to SUV for predicting tumor response as well as understanding temporal changes during treatment in gynecological cancers. An additional experiment was performed studying the variability of texture features from baseline and intra-treatment PET scans due to reconstruction parameters in order to identify features that show statistically significant changes during treatment and that are independent of reconstruction parameters.

In this IRB approved clinical research study, 29 women with node positive gynecological malignancies visible on PET including cervical, endometrial, vulvar...

Expansion of the 4D XCAT Phantom Library with Anatomical Texture
Bond, Jason
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Tese de Doutorado
Publicado em //2013
Relevância na Pesquisa
362.9633%
#Medical imaging and radiology#Computerized phantoms#CT#Simulation#Texture synthesis#XCAT

Computational phantoms are set to play an important role in imaging research. As medicine moves increasingly towards providing individualized, patient-specific care, it is imperative that simulations be completed on patient-specific anatomy, rather than a reference standard. To that end, there is need for a variety of realistic phantoms for clinical studies.

This work adds to the existing extended cardiac and torso (XCAT) adult phantom series (two phantoms based on visual human data) by building new models based on adult patient computed tomography (CT) image data. These CT datasets were obtained from Duke University's patient CT database.

Each image-set was segmented using in-house segmentation software, defining bony structures and large organs within the field of view. 3D non-uniform rational b-spline (NURBS) surfaces were fitted to the segmented data. Using the multi-channel large diffeomorphic deformation metric mapping (MC-LDDMM) network, a transform was calculated to morph an existing XCAT model to the segmented patient geometry. Fifty-eight adult XCAT models were added to the phantom library.

In addition to the expanding the XCAT library, the feasibility of incorporating texture was investigated. Currently...

Periodicity and Texel Size Estimation of Visual Texture Using Entropy Cues
Lizarraga Morales,Rocío; Sánchez Yáñez,Raúl E.; Ayala Ramírez,Víctor
Fonte: Centro de Investigación en computación, IPN Publicador: Centro de Investigación en computación, IPN
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2011 EN
Relevância na Pesquisa
361.1114%
#Image Processing#Texture#Size and Shape#Texture Periodicity#Entropy
Texture periodicity and texture element (texel) size are important characteristics for texture recognition and discrimination. In this paper, an approach to determine both, texture periodicity and texel size, is proposed. Our method is based on the entropy, a texture measure computed from the Sum and Difference Histograms. The entropy value is sensitive to the parameters in such histograms and takes its lowest value when the parameters match with texel size or its integer multiples, in any specific direction. We show the performance of our method by texture synthesis, tiling a sample of the detected size and measuring the similarity between the original image and the synthesized one, showing good results with regular textures and texels with different shapes, being useful for practical applications as well because of its simple implementation.