| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 4.81 MB | Adobe PDF |
Authors
Advisor(s)
Abstract(s)
A incidência de diversas patologias no sistema cardiovascular constitui uma elevada importância
na compreensão e antevisão do comportamento dos elementos sanguíneos.
O objectivo principal deste trabalho é desenvolver um método semi-automático para o cálculo
do coeficiente de dispersão dos eritrócitos. O coeficiente de dispersão permite-nos avaliar o comportamento
do escoamento do eritrócito, relativamente à suas flutuação no fluido. Desta forma é
possível substituir os métodos manuais existentes por um método mais simples e portanto mais
fácil de utilizar, bastante mais rápido de implementar e mais eficaz, diminuindo a possibilidade
de ocorrência de erros. Para isso foi necessário efectuar o seguimento de elementos (partículas
fluorescentes e eritrócitos humanos) ao longo de uma sequência de imagens captadas no centro de
um microcanal produzido em polidimetilsiloxano, através do software Image J para a obtenção
dos valores do deslocamento radial. Para o cálculo do coeficiente de dispersão foi desenvolvido
um método em programação MatLab.
O método desenvolvido foi aplicado em diversos segmentos de imagens e foi comparado
com um método manual aplicado que recorre ao Microsoft Office Excel para o cálculo do coeficiente
de dispersão. Após a análise dos diversos resultados, foi verificado que o método
semi-automático desenvolvido efectuou correctamente o cálculo do coeficiente de dispersão de
elementos sanguíneos em microcanais.
O método desenvolvido foi aplicado na sequência de imagens de forma a analisar a influência de uma bifurcação, divergente e convergente, no comportamento dos elementos existentes nos
fluidos em questão. Para o caso das partículas fluorescentes em água pura não se verificou qualquer
alteração dos valores do coeficiente de dispersão, o que significa que a montante e a jusante
das bifurcações, estas não têm qualquer influência no seu comportamento. Contrariamente, no
caso dos eritrócitos em D 40 verificou-se que após a presença de uma bifurcação convergente
ocorre um aumento dos valores do coeficiente de dispersão.
The incidence of various pathologies in the cardiovascular system constitute a high importance on understanding and foresight of the behavior of blood elements. The main objective of this work is to develop an semi-automated method to calculate the dispersion coefficient. The dispersion coefficient allows us to evaluate the behavior of the erythrocyte flow, relatively to it fluctuation in the fluid. In this way it’s possible to replace the existing manual methods by a method simpler and therefore easier to use, much faster to implement and more effective, reducing the possibility of occurring errors. For that it was necessary to perform the tracking of the elements (fluorescent particles and human erythrocytes) over an image sequence captured in the center of polydimethylsiloxane microchannel, through the Image J software to obtain the values of radial displacement. To calculate the dispersion coefficient a method was developed in MatLab programming. The method has been applied in various segments of images and has been compared with a manual method applied that uses the Microsoft Office Excel to calculate the dispersion coefficient. After the analysis of the various results, it was verified that the semi-automated method developed has performed correctly the calculation of the dispersion coefficient of blood components in microchannels. The developed method was applied in the image sequence in order to analyze the influence of a bifurcation, divergent and convergent, in the behavior of the existing elements in the fluids in question. For the case of fluorescent particles in pure water there was no alteration of coefficient of dispersion, which means that the upstream and downstream of bifurcations, they have no influence on they behavior. Contrary, in the case of erythrocytes in D 40 it was verified that after the presence of a bifurcation convergent there is an increase of the coefficient of dispersion.
The incidence of various pathologies in the cardiovascular system constitute a high importance on understanding and foresight of the behavior of blood elements. The main objective of this work is to develop an semi-automated method to calculate the dispersion coefficient. The dispersion coefficient allows us to evaluate the behavior of the erythrocyte flow, relatively to it fluctuation in the fluid. In this way it’s possible to replace the existing manual methods by a method simpler and therefore easier to use, much faster to implement and more effective, reducing the possibility of occurring errors. For that it was necessary to perform the tracking of the elements (fluorescent particles and human erythrocytes) over an image sequence captured in the center of polydimethylsiloxane microchannel, through the Image J software to obtain the values of radial displacement. To calculate the dispersion coefficient a method was developed in MatLab programming. The method has been applied in various segments of images and has been compared with a manual method applied that uses the Microsoft Office Excel to calculate the dispersion coefficient. After the analysis of the various results, it was verified that the semi-automated method developed has performed correctly the calculation of the dispersion coefficient of blood components in microchannels. The developed method was applied in the image sequence in order to analyze the influence of a bifurcation, divergent and convergent, in the behavior of the existing elements in the fluids in question. For the case of fluorescent particles in pure water there was no alteration of coefficient of dispersion, which means that the upstream and downstream of bifurcations, they have no influence on they behavior. Contrary, in the case of erythrocytes in D 40 it was verified that after the presence of a bifurcation convergent there is an increase of the coefficient of dispersion.
Description
Keywords
Coeficiente de dispersão Método semi-automático Seguimento de elementos