Estudo de fantomas e tecidos biológicos por meio de mapas de absorção e espalhamento ópticos obtidos pela técnica de imagem no domínio da frequência espacial

Abstract

When detected early, skin cancer can have great chances of cure and one of the current forms of diagnosis performed by dermatologist physicians consists of biopsy. Therefore, during this exam, part of the suspicious tissue is collected and then it is sent to a pathological anatomy laboratory, where the observation report will be issued. However, this process is invasive and neglects the evolution of the disease. In order to overcome these problems, this research aims to propose a new methodology to detect skin cancer using the Spatial Frequency Domain Imaging technique (SFDI). In the theoretical part, the present research was based on CUCCIA (2009), TUCHIN (2000), BODENSCHATZ (2015), and others. In relation to the SFDI technique, it consists in an optical method that uses wide field geometry and which is non-invasive and non-contact. In addition, this technique is capable of interrogate skin depths of about 1 to 5 mm and quantifies the concentrations of clinically relevant chromophores such as oxyhemoglobin, deoxyhemoglobin, lipids, water and melanin by spatial maps of the absorption coefficient 𝜇𝛼 and reduced scattering coefficient (𝜇𝑆′ ). Regarding the research methodology, the developed SFDI device consists in a light microprojector which is used for projections of sinusoidal patterns at different spatial frequencies on the sample surface, so that the diffuse reflection that comes is captured using a CCD camera which has six filters for the wave length selection (530, 650, 680, 750, 780 and 810nm). The technique was previously applied in the study of phantoms as optical properties similar to those of the biological tissues for equipment calibration and, subsequentially, in the measures in ex vivo and in vivo. The results obtained by the SFDI were compared to the results obtained from an integrating sphere and were satisfactory for biomedical applications.