Aplicação da técnica da imagem no domínio da frequência espacial para o estudo da profundidade de penetração da luz em fantomas ópticos que simulam o tecido epitelial

Abstract

Nowadays, a new technique of optical processing, called SFDI (Spacial frequency domain imaging), has emerged as a method for the diagnosis and treatment of diseases, traumas and tumors caused in the epithelial tissue. This technique is characterized by being non-invasive and innovative, that allows to quantify absorption values and reduced scattering on a pixel-by-pixel basis. In addition, this method can be applied in opaque media such as in biological tissues to determine optical wavelength dependent parameters. The objective of this work is to develop the study of optical properties, such as absorption and scattering, in addition to finding the depth levels of light penetration in phantoms that simulate the biological tissue from SFDI. Another equipment was used to obtain the optical parameters, called the integrating sphere, in order to compare the data obtained. To this it was produced a calibration phantom with known optical parameters and two simulators epithelial tissue phantoms. The calculations of the absorption and reduced scattering coefficients was realized using the diffuse reflectance model and propagation of light. Five filters were used, such as λ = 475 nm, 488 nm, 532 nm, 580 nm e 650 nm, and four spatial frequencies Kx = 0,07 mm-1, 0,1 mm-1, 0,3 mm-1 e 0,4 mm-1. For these, we conclude that the frequency of 0.1 mm-1 became a limit to obtain the depths of light penetration in the medium, since it was not possible to obtain it for Kx = 0,07 mm-1 and for the other frequencies the depths were δ = 4.92 mm, 3.83 mm and 2.60 mm, respectively. In addition, Kx = 0.1 mm-1 is the frequency that best presents a real application in the epithelial tissue, because the light beam is able to penetrate the entire tissue extension. Therefore, SFDI has been shown to be an effective method of image processing, and its results demonstrate future in vivo applications for developing optical tomography.