Design, production and characterization of dichroic filters for use in photodynamic therapy and diagnostics

Photodynainic therapy (PDT) and photodynamic diagnosis (PDD) are new methods in treatment of certain skin carcinoma, some other skin diseases as well as in treatments of some other internal organ carcinoma. The combination of photosensitizing drug and light, in the presence of molecular oxygene is used to obtain a therapeutic and diagnostic effects. The wavelength and intensity of the light depend on the photosensitiser used. For aminolevulinic acid (5-ALA), in PDD violet light is used while red light is detected. In PDT red light is used. In PDD the separation of excitation and absorption is needed. For additional protection of patients and therapeuts it is necessary to filtrate the light in UV and red parts of spectrum. The basic problem has been to design and produce interference filters which fulfill the above conditions. The design has been made by comercial computer programs which resulted by deposition of filters composed of multileyers of dielectric oxide materials (TiO2 and SiO2). Produced filters have been characterized and it is confirmed that they fulfill all wanted properties.