Percorrer por autor "Lima, M.J."
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- Human femur assessment using isotropic and orthotropic materials dependent of bone densityPublication . Fonseca, E.M.M.; Lima, M.J.; Barreira, LuísaThe bone mass reduction and the deterioration of the tissue micron-architecture lead to a bigger fragility of the bone and to the consequent increase of the fracture risk. For this fact, it is considered excellent the quantification of the mass density and the verification of its influence in the bone resistance assessment. The apparent density is defined as the density without fluid influence, being the effective density at that includes the marrow mass, essentially fluid. This measurement is made through the use of a gray scale values on the medical image in study. The values in Hounsfield units are determined, being this scale later converted into measure of the bone density. With this measure an exponential relation will be used allowing calculate the biomechanics properties dependence for cortical and trabecular bone. With this work it is intended to assessment the susceptible weak zones, for a human femur with 70 years old, using the finite element method through ANSYS® program. The main objective is obtaining the stresses distributions, using different values of bone density and their relation with exponential laws for isotropic and orthotropic materials properties.
- Human femur assessment using isotropic and orthotropic materials dependent of bone densityPublication . Fonseca, E.M.M.; Lima, M.J.; Barreira, LuísaThe bone mass reduction and the deterioration of the tissue micron-architecture lead to a bigger fragility of the bone and to the consequent increase of the fracture risk. For this fact, it is considered excellent the quantification of the mass density and the verification of its influence in the bone resistance assessment. The apparent density is defined as the density without fluid influence, being the effective density at that includes the marrow mass, essentially fluid. This measurement is made through the use of a gray scale values on the medical image in study. The values in Hounsfield units are determined, being this scale later converted into measure of the bone density. With this measure an exponential relation will be used allowing calculate the biomechanics properties dependence for cortical and trabecular bone. With this work it is intended to assessment the susceptible weak zones, for a human femur with 70 years old, using the finite element method through ANSYS® program. The main objective is obtaining the stresses distributions, using different values of bone density and their relation with exponential laws for isotropic and orthotropic materials properties.
- A influência da densidade óssea aparente na simulação de um fémur humanoPublication . Lima, M.J.; Fonseca, E.M.M.; Teixeira, Cristina; Barreira, LuísaA redução da massa óssea e a deterioração da micro-arquitectura do tecido leva a uma maior fragilidade do osso e ao consequente aumento de risco de fractura. Por este facto, considera-se relevante a quantificação da densidade de massa óssea e a verificação da sua sua influência de fluído, sendo a densidade efectiva a que inclui a massa de medula, essencialmente fluída. Essa medição é efectuada através da utilização de uma escala de valores cinza sobre a imagem médica em estudo. Inicialmente são determinados os valores de cálculo em unidades de densidade Hounsfield, sendo esta escala posteriormente convertida em medida da densidade óssea. Com base nesse registo, utilizar-se-á uma relação exponencial que permita calcular a dependência das propriedades biomecânicas do osso cortical e do osso trabecular da estrutura. Com este trabalho pretende-se verificar as zonas mais susceptíveis de fractura, no colo do fémur de um paciente de 70 anos utilizando o método de elementos finitos através do programa ANYSIS, para a obtenção das distribuições das tensões e deformações, nas diferentes situações de densidade óssea calculada.
- The thickness of the cortical bone in different maxillae using medical imagesPublication . Fonseca, E.M.M.; Lima, M.J.; Noronha, J.K.; Vaz, M.A.P.The aim of the present study was to investigate whether there is a relationship between the thicknesses of the cortical bone of mandible human and the age and the sex of patient. In this work the measure of the cortical bone thickness was obtained in different computed tomography (CT) dental of medical images. Different human mandibles were scanned using high resolution micro‐CT instrument in which many axial slices were obtained, see figure 1. Pixel by pixel for each slice and using image control system software, different layers were measured. A total of four medical images were studied and observed. Two different groups were characterized. The first one, with two female mandibles (F): an old and a young patient. The second group of two males mandibles (M), with similar age. A comparison between the male and female sex was also obtained. The cortical bone thickness of the mandible may be affected by tooth extraction, age and sex patient. The use of this type of information is useful for complementary diagnostic information and treatment planning.
- The thickness of the cortical bone in different maxillae using medical imagesPublication . Fonseca, E.M.M.; Lima, M.J.; Noronha, J.K.; Vaz, M.A.P.The aim of this study was to investigate whether there is a relationship between the thickness of the cortical bone of mandible human and the age and the sex of patient. In this work the measure of the cortical bone thickness was obtained in different computed tomography (CT). Different human mandibles were scanned using high resolution micro-CT instrument in which many axial slices were obtained. A total of four medical images were studied and observed. Two different groups were characterized. The first one, with two female maxillae (F): an old and a young patient. The second group of two males mandibles (M), with similar age. A comparison between the male and female sex was also obtained. The cortical bone thickness of the mandible may be affected by tooth extraction, age and sex patient. The use of this type of information is useful for complementary diagnostic information and treatment planning.