New light source for PDT of skin lesions

Since coherence of laser light is not necessary for PDT of skin tumors, attempts have been made to construct incoherent lamps. A recent development is PDT 1200 (Waldmann Medizintechnik/FRG), a light source based on a 1200 watt metal halogen lamp. Emission of 580 to 740 nm radiation is achieved by using cut off filters. Power density can be varied from 30 mW/cm2 to 200 mW/cm2 in an area from 100 to 300 cm2. Biologic effectiveness was proved by comparison with the radiation of an argon-pumped dye laser emitting light at 630 nm. Three human cell lines were incubated with photofrin (5 (mu) g/ml and 10 (mu) g/ml) for 24 hours. After irradiation a MTT-test was performed to assess cell viability. Results clearly proved biological effectiveness of the light source PDT 1200. No significant difference in cell viability was detected using either concentration of sensitizer. Therefore, we believe that PDT 1200 is a promising new light source for photodynamic therapy of skin lesion.