20 Bronchology – Past, Present and Future Diagnostic Procedures 1.  Photofluorescence (Hayata-Kato) with Krypton-ion Laser Beam and Photodynamic Therapy In 1982, Hayata and Kato developed a bronchoscopy system for early detection of tumors by photo-radiation. The principle of fluorescence diagnosis is that hematoporphyrin (HPD) or porphyrin derivatives emit real fluorescence when excited by violet light. The concentrations of HPD and porphyrin are higher in malignant tumors than in non-malignant tissue. The patient is given an i.v. in- jection of HPD (3 to 5 mg/kg) and 72 hours later optimal differentiation between tumor and normal tissue is made possible. The patient undergoes broncho- scopy with a fiberscope under local anesthesia. The tumor can be illuminated using a krypton-ion laser light source (406 nm, 647 nm) for Photo-Radiation Treatment (PRT) / Photodynamic Therapy (PDT). The tumor mass is exposed to red light using a gold vapor laser (628 nm) for about 15 minutes. Unfortunately, there are serious side effects including the risk of hemorrhage in advanced cases. Light sensitization of the skin is very fatiguing. Sleep rhythms can be reversed and occasionally diarrhea may occur. The patient has to stay indoors for two to three weeks following the operation. Fig. 16 Schematic Drawing of Photofluorescence (Hyata-Kato) with Krypton-ion Laser Beam and Photodynamic Therapy Tumor Broncho- Fiberscope Bronchus Barrier Filter Diaphragm Image intensifier Eye Quartz Light Guide Interference Filter Krypton-ion Laser Light Source Back –––––––Table of Contents–––––––Next Back –––––––Table of Contents–––––––Next