Effect of negative pions on the proliferative capacity of ascites tumor cells (lymphoma) grown in vivo

Abstract

,. Effect of negative pions on the proliferative capacity of ascites tumor cells (lymphoma) in vivo.' Radiation Res.pp.-, _ I - ABSTRACTWe have attempted t o determine the relative biological effective -.ness (RBE) of negative pions in the Bragg-peak region as compared t o the plateau region and to gamma rays. We irradiated LAF1 mice, bearing 5-day-old lymphoma ascites tumors, in the peak and plateau regions of a cobalt-60 gamrna rays. We calculated peak doses from those at the plateau, using a measured average peak-to-plateau ionization ratio of 1.5.' Doses in the plateau region rangedfrom 145 to 250 rads; doses in the peak region ranged f r o m 220 to 380 rads. The survival curve for cells irradiated in the peak region gave a Do of 65 f 15 rads. The plateau points were not reliable. , A replicate experiment was performed using Coao y-rays, yieldinga survival-curve Do of 350 f 50 rads. a n RBE of 5.4 * 1.8 is obtained for negative pions in the peak region, based . .

Recent developments in fundamental radiobiology

“…'The authors point out that about half the close in the Bragg peak is due to contaminalion from other types of particles and that further experiments, using cleaner beams, are required to determine more clearly the effects of the pions alone. Feola et al 7 have reported experiments comparing the survival of lymphoma cells irradiated in vivo by negative pions with Cobalt 60 irradiation under similar conditions. Mice bearing 5-day-old lymphoma ascites tumors were irradiated for 40 homs under temperature control.…”