Effect of negative pions on the proliferative capacity of ascites tumor cells (lymphoma) grown in vivo Page: 4 of 26
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J. M. -FEOLA, C. RICHMAN, M., R. RAJU, S. B. CURTIS, and
J. H. LAWRENCE,. Effect of negative pions on the proliferative capacity
of ascites tumor cells (lymphoma) in vivo. Radiation Res. , pp. -
We have attempted to determine the relative biological effective-
ness (RBE) of negative pions in the Bragg-peak region as compared to
the plateau region and to gamma rays. We irradiated LAF mice, bearing
5-day-old lymphoma ascites tumors, in the peak and plateau regions of a
90-MeV pion beam for 40 hours in temperature-controlled holders. The
animals were then sacrificed; lymphoma cells -were withdrawn and titrated
into adult female LAFI mice. The proliferative capacity of the irradiated
tumor cells was evaluated after 8 weeks by observing the percentage of
animals. developing ascites tumors. Surviving fractions were then calculated
from LD50' s of control and irradiated animals. . Radiation doses in the
plateau region were measured with LiF dosimeters calibrated against
cobalt-60 gamma 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 ranged' from 145 to 250 rads; doses in the peak region
ranged from 220 to 380 rads. The survival curve for cells irradiated in
the peak region gave a D0 of 65 + 15 rads. The plateau points were not
reliable. . A replicate experiment was performed using Co y-rays, yielding.
a survival-curve D0 of 350 t 50 rads. If the y-ray D0 is taken as a baseline,
an RBE of 5.4 + 1.8 is obtained for negative pions in the peak region, based
on the ratio of.peak-region D0 to Co D0.
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Feola, J.M.; Richman, C.; Raju, M.R.; Curtis, S.B. & Lawrence, J.H. Effect of negative pions on the proliferative capacity of ascites tumor cells (lymphoma) grown in vivo, report, March 30, 1967; California. (digital.library.unt.edu/ark:/67531/metadc623285/m1/4/: accessed January 22, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.