Desenvolvimento e avaliação de um sistema de imagem multiespectral para o diagnóstico óptico de lesões neoplásicas. / Assembly and evaluation of a multispectral widefield imaging system for the detection of malignant lesions.

AUTOR(ES)

Sebastião Pratavieira

DATA DE PUBLICAÇÃO

2010

RESUMO

The increase of life expectancy associated to healthless habits results in a higher probability of tumor development. In this sense, cancer has been increasingly considered an important health public concern. The conventional methods for cancer detection are not efficient for the acquisition of a fast and precise diagnostics. In this study we present a widefield imaging system for optical detection of tissue changes based on fluorescence and reflectance. The development of the imaging system involves the device assembly as well as a proposed image processing. For the acquisition of fluorescence and reflectance images a system with a high resolution color CCD camera together with LED-based light source was built. A LED emitting at 400 nm and an optical filter were used for fluorescence imaging. The reflectance images were acquired at five spectral intervals: UV, blue, green, red, and white. After the acquisition of this set of images it is possible to merge a multispectral image of the target tissue, where each image type provides distinct information from the investigated sample. For the determination of the regions that present different optical characteristics, a k-means algorithm was used. An in vivo animal model of UV-induced skin lesions at hairless mice was used for system validation. In order to obtain the multispectral image of a lesion, a fluorescence image and five reflectance images were acquired. To complete the multispectral image, an image of the ratio of the red to green components of fluorescence image was added, because during malignant development a change of this ratio is observed. The use of different image types allows the increase of the discrimination contrast of distinct regions after an image processing it was possible to discriminate optically different regions, a result that is relevant for lesion detection and delimitation.

ASSUNTO(S)

fluorescência multispectral image refletância image processing processamento de imagens fluorescence reflectance imagem multiespectral

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