Since 1976, photodynamic therapy (PDT) has been used for the treatment of different stages of urothelial bladder tumors. First applications were based on the irradiation of single exophytic tumors using bare fibers for laser irradiation (630 mm) or bright white light generated e.g. from a mercury arc lamp. Clinical results of several centers demonstrated the possibility of destroying single superficially growing tumors. A new approach to the treatment of multifocal growing tumors, including the endoscopically often undetectable carcinoma in situ, was provided by the development of treatment modalities allowing for whole bladder wall irradiation. Photodynamic diagnosis (PDD) is a novel procedure for detecting flat precancerous and malignant lesions undetectable by endoscopy alone on the basis of laser- induced fluorescence.
"Present status of photodynamic procedures in urology", Proc. SPIE 2078, Photodynamic Therapy of Cancer, (1 March 1994); doi: 10.1117/12.168673; https://doi.org/10.1117/12.168673