Power density of laser radiation as a primary importance factor in PDT
Abstract
By animal experiments of last years, a special role of radiation power density in PDT was established: tumor irradiation with the same dose of light energy but different power densities (and accordingly, exposures) revealed in many cases an advantage of the regimen in which a low power density and more prolonged irradiation time were used. To verify the data, we exploited an analogical approach in experiments in vitro with a human leukemia cell culture Namalwa as a PDT target. The studies, performed with two different photosensitizers – Photolon (chlorin e6) and hematoporphyrin, showed that under equal irradiation doses, reduction of light power density by two or three times led to increase of dead cell numbers by 1.8 - 2,3 times. The results of additional experiments, in which kinetics of cell death was followed, allow to come nearer to understanding of mechanisms of the phenomenons observed.Downloads
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