HpD PHOTODYNAMIC THERAPY-PRELIMINARY STUDIES-

Abstract

Preliminary studies on photodynamic therapy (PDT) with hematoporphyrin derivative (HpD) and dye laser were performed and the following results were obtained. 1. N₂ and Ar dye lasers were irradiated at dog's liver surface after HpD administration to examine which one is more effective in PDT. Under the same average power (50mW), N₂ dye laser (pulse wave laser) was about 10% more effective than Ar dye laser (continuous wave laser). 2. The relation between condition of laser irradiation and effect of PDT with N₂ and Ar dye laser were also studied by the same method. The larger the total energy became, the deeper the tissue damage. The depth of tissue damage was not always in proportion to the total energy. Low power and long time irradiation is more effective than high power and short time irradiation under the same energy. 3. To assess the infulence of PDT on non-cancer tissue after HpD administration, N₂ dye laser was irradiated at normal dog's gastric mucosa and ulcers made by Nd-YAG laser. Shallow ulcers (U1-II) were formed in normal mucosa, but the ulcers irradiated with dye laser became worse and some ulcers extended to serosa. When PDT applicated to a cancer lesion with ulceration, it is necessary to pay attention to perforation of the lesion.