The application of a compact multispectral imaging system with integrated excitation source to in vivo monitoring of fluorescence during topical photodynamic therapy of superficial skin cancers

A novel, compact and low-cost multispectral fluorescence imaging system wit h an integrated excitation light source is described. Data are presented de monstrating the application of this method to in vivo monitoring of fluores cence before, during and after topical 5-aminolevulinic acid photodynamic t herapy of superficial skin cancers. The excitation source comprised a fluor escent tube with the phosphor selected to emit broadband violet light cente red at 394 nm. The camera system simultaneously captured spectrally specifi c images of the fluorescence of the photosensitizer, protoporphyrin IX, the illumination profile and the skin autofluorescence. Real-time processing e nabled images to be manipulated to create a composite image of high contras t. The application and validation of this method will allow further detaile d studies of the characteristics and time-course of protoporphyrin IX fluor escence, during topical photodynamic therapy in human skin in vivo.