Two-color fluorescence monitoring in PDT treatment

The fluorescence imaging device for localizing a tumor in a patient's body and monitoring photobleaching of a photosensitizer (PS) in course of photodynamic therapy was constructed. The system includes two LED sources at 405 and 660 nm for excitation of chlorine-based PSs. The ratio of fluorescence signals upon excitation at these wavelengths was demonstrated to provide evaluation of PS penetration depth in biotissues after topical administration. The study included Monte Carlo simulations that are in a good agreement with phantom experiment.