Double ratio fluorescence imaging for the detection of early superficial cancers

We have developed a fluorescence imaging device for the detection of superficial cancer based on the double ratio technique. In practice this device resembles an operation microscope and can be used in a clinical environment. This device acquires four different fluorescence images excited at two wavelengths and detected at two wavelengths. From these images it calculates, displays, and stores double ratio images at a maximum speed of 1 Hz. The double ratio image gives the distribution of the amount of fluorophore present in tissue and is not affected by local variations in tissue optics, i.e., tissue absorption and tissue scattering. The validity of the technique was confirmed by ex vivo tissue equivalent phantom experiments using hematoporphyrin and in vivo experiments on normal pigmented moles on Caucasian human skin using delta -aminolevulinic acid induced Protoporhyrin IX. (C) 2001 American Institute of Physics.