Fluorescence detection of superficial skin cancers

We present a simple fluorescent diagnosis system for the demarcation of skin cancers. 5-aminolaevulinic acid (ALA) cream is applied to the suspicious area resulting in the accumulation of the photosensitizer Protoporphyrin IX (PpIX) in the cancerous tissue. When excited at 400 nm using a filtered mercury arc lamp, the PpIX fluoresces at 635 nm. Our imaging system acquires four spectrally specific images at 635, 540, 470 and 400 nm for the PpIX fluorescence, natural skin autofluorescence and illumination respectively. Subsequent image processing combines these images into a single display showing clearly the localization and extent of the tumour.