Aplicação da técnica da imagem no domínio da frequência espacial para mapeamento óptico em profundidades do tecido epitelial voltada para o diagnóstico de lesões

Abstract

In this thesis, we investigated the use of the Spatial Frequency Domain Imaging (SFDI) technique and the Integrating Sphere to characterize the optical properties of phantoms containing Gold Nanoparticles (NpAu) and, additionally, Zinc Phthalocyanine (ZnPc). To this end, we used 650 nm filters, characterizing the phantoms at different spatial frequencies and depths. As a result, we observed that the measured absorption coefficients (μₐmed) varied with concentration and depth, decreasing with increased depth due to light attenuation and increasing with spatial frequency up to an optimal point at 0.1 mm⁻¹. Furthermore, we derived a mathematical expression to estimate the light penetration depth from the obtained coefficients. Moreover, the comparison with the expected absorption coefficients showed that the measured values are generally higher, possibly due to experimental variations. Thus, the SFDI technique proved effective up to a depth of 3.0 mm, validating its applicability in the optical mapping of biological tissues. In conclusion, the main findings highlight the robustness of SFDI in analyzing phantoms with NpAu, contributing to the advancement of non-invasive diagnostic techniques in biomedical optics.