Abstract

Fluorescence images, based on the emission of endogenous or exogenous fluorophores, are being investigated for cancer diagnosis. Several photosensitizers, presently studied for the Photodynamic therapy of tumors, localize in neoplastic tissues more than in healthy surrounding ones and are fluorescent. Therefore, they are also suitable markers for diagnosis. A non-invasive diagnostic procedure calls for sensitizer doses much lower than the therapeutic ones. In such a condition, the exogenous fluorescence is very faint, and can be overcome by the natural tissue fluorescence. The enhancement of the signal to noise ratio can be achieved using either spectral filters (multicolor imaging) or a time gated acquisition. Multicolor imaging is based on the acquisition of three spectrally different images, one in the red region, which mainly collects the exogenous signal, one in the green-yellow region, which accounts for natural fluorescence, and one in the blue region, for normalization purposes. A pseudo-image is then calculated using a suitable mathematical algorithm.

© 1998 IEEE