We developed new metal-halide lamps for photodynamic diagnosis (PDD) and photodynamic therapy (PDT). The metal-halide lamps were made by introducing mercury gas and metal halide such as sodium iodide (Na lamp), lithium iodide (Li lamp), potassium iodide (K lamp), rubidium iodide (Rb lamp), and sodium iodide-lithium iodide mixture (Na-Li lamp), into their discharge tubes. These lamps emitted light at 405, 436, 546, and 577 nm induced by mercury gas. Moreover, the lamps had specific emission peaks at 610 nm for the Na lamp, 612 and 674 nm for the Li lamp, 780 nm for and Rb lamps, and 612 and 674 nm for the Na-Li lamp. These peaks were attributable to the metal elements in each lamp. By comparison the optimum excited wavelength of the metal halide lamps, with the absorption spectra of photosensitizers usually used for PDT in the medical fields, Na and Na-Li lamps were effective in exciting hematoporphyrin and 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX), respectively, and Li lamp effectively excited N-aspartyl chlorine e6 and ATX-S10. We also developed two types of optical light sources using the metal-halide lamps; one was a fiber type and the other directly irradiating type. The wavelength of light emitted from the light sources could be exchanged between about 400 nm for PDD and 600-700 nm for PDT by using filters, We investigated the PDT efficiency in vitro for EL-4 cells of the fiber type of optical light sources adopting the metal-halide lamps developed. As a result, the optical light source with the Na-Li lamp was most effective in killing EL-4 cells. In addition, we treated solar keratosis and acne vulgaris using the optical light sources adopting Na-Li lamp, and found that the light sources were effective in treating these diseases.

View full abstract