Piotron pion irradiation of cerebral capillaries in neonatal rats: Relative biological effectiveness and radioprotection by 0-(beta-hydroxyethyl)-rutosides

The microvasculature of the neonatal rat brain and its radiation-induced petechial hemorrhages were used as an in vivo model for studying the effect of negative pions on healthy normal tissue. By means of dose response curves (range: 2-6 gray) the RBE of peak pions with respect to 220 kVp X-rays was calculated. Whereas earlier studies involved irradiations with single beam pions ( pi E3) of low dose rate (0.06-0.11 Gy per min) the present work was performed usng pions of a multiport applicator (Piotron) of higher dose rate (1 Gy per min). The results obtained by Piotron pions agreed well with those obtained by pi E3 pions resulting in a RBE of 1.1.