Differential optical spectropolarimetric imaging system assisted by liquid crystal devices for skin imaging

摘要

Skin cancer diagnosis depends not only on histopathological examination but also on visual inspectionnbefore and after the excision of suspected lesion. Neoplasm is accompanied with changes in birefringence ofncollagen, pleomorphicity, and hyperchromatic state of epithelial nuclei. These phenomena can be measured bynspectral and polarization changes of light backscattered by the examined tissue. A new differential spectropolarimetricnsystem is proposed using liquid crystal devices, one as a tunable filter and the other as a polarizationnrotator, both operating at wide spectral ranges from the visible to the near-infrared. Since collagen’s fibrils texturenorientation depends on its location in the skin and since it is not well organized, our system scans the bipolarizationnstates by continuously rotating the linearly polarized light incident on a skin lesion, and collecting differentialncontrasts between sequenced images when simultaneously averaging the statistical readout of a video camera.nThis noninvasive method emphasizes areas on skin where the neoplasm, or tumor, minimizes the statistical polarizationnchange of the scattered light from the lesion. The module can be considered as an assistant tool fornepiluminescence microscopy. Images of skin tumors were captured in vivo before the patients having their surgerynand compared to histopathological results.