Abstract
We carried out basic studies on the diagnostic accuracy and clinical evaluation of a system involving administration of HpD against malignant tumors and N2 dye laser (Molectron Co. Model 8910) photoradiation, and obtained the following results. The laser beam emitted from N2 dye laser is a discontinous wave, but it could be seen macroscopically as continuous one when pulse repetition was increased to 60 pps or more. Therefore, observation of fluorescence of HpD did not be disturbed. At the tip of the light guide fiber of N2 dye laser, average power was as low as 23 mW, but peak power was as high as 38 KW, which was sufficient to excite HpD. The mininum HpD value detected using a diluted solution of HpD (5 mg/cc) was 5×10-4pg. In human stomach cancer and mouse transplanted tumors (Sarcoma and carcinoma), fluorescence could be observed even to the thickness of 50 p, 48-72 hours after the administration of 3 mg/kg of HpD. In the observation of fluorescence of HpD, 0.3% indigocarmine solution in dye spraying method did not disturbed, but fresh blood, mucus and white coating on lesion disturbed. Since usefulness of N2 dye laser was demonstrated by this basic study, we will attempt application of this system consisting of the laser and an image intensifier (30, 000 fold) in endoscopy.
