[Cellular responses to multifractionated irradiations].
Several models for dose survival curves in vitro had been proposed by many target, linear quadratic and so on. One of them is a linear quadratic (LQ) model which is described by the equation of E = e-(alpha d + beta d2). Also, the alpha/beta radio for radiation responses of normal or tumor tissues can be determined by their iso-effect relationships. Recently, the studies of LQ model in vitro and in vivo induced to new regimens of radiation therapy: hyperfractionation and superfractionation. The studies for cell growth in multifractionation indicated that the irradiated cells can grow within 4 fractions with daily dose of 2 Gy, thereafter an accumulation of G1 and G2 block were observed. However cell growing fraction seems to be relatively few in the irradiation conditions of more than 3 Gy of daily dose.
Division of Radiaton Hazards, National Institute of Radiological Sciences.
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Tsuboi
D000818:Animals; D002470:Cell Survival / Q000528:radiation effects*; D004273:DNA, Neoplasm / Q000528:radiation effects; D006801:Humans; D051379:Mice; D008954:Models, Biological; D009374:Neoplasms, Experimental / Q000473:pathology / Q000532:radiotherapy*; D011878:Radiotherapy / Q000379:methods*; D011879:Radiotherapy Dosage
D004273:DNA, Neoplasm