Fluence Rate Effects in Photodynamic Therapy of Multicell Tumor Spheroids

摘要: Abstract EMT6/Ro spheroids approximately 500 µm in diameter were subjected to photodynamic therapy administered at various incident radiation fluence rates. Following 24 h incubation with 10 µg/ml Photofrin, groups of irradiated 630 nm an identical 60 J/cm2, delivered rates ranging from 25 200 mW/cm2. After treatment, dissociated, cell yields determined, and surviving cells assayed for their colony-forming ability. A fraction was calculated each treatment group by computing the product fractional yield plating efficiency. The results exhibit a strong dependence on rate, fractions decreasing 0.5 0.07 as rate lowered These data analyzed using mathematical model photochemical oxygen consumption undergoing therapy. Calculations showed that therapy-induced creates hypoxic volumes within which would be protected singlet oxygen-mediated damage magnitude these depends rate. spheroid survival consistent such interpretation.