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

Description: We have attempted to determine the relative biological effectiveness (RBE) of negative pions in the Bragg-peak region as compared to the plateau region and to gamma rays. We irradiated LAF{sub 1} 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 The animals were then sacrificed; lymphoma cells were withdrawn and titrated into adult female LAF{sub 1} mice.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 LD{sub 50}`s of control and irradiated animals. Radiation doses in the 50 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 D{sub 0} of 65 {plus_minus} 15 rads. The plateau points were not reliable. A replicate experiment was performed using Co{sup 60} {gamma}-rays, yielding a survival-curve D{sub 0} of 350 {plus_minus} 50 rads. If the {gamma}-ray D{sub 0} is taken as a baseline, an RBE of 5.4 {plus_minus} 1.8 is obtained for negative pions in the peak region, based on the ratio of-peak-region D{sub 0} to Co{sup 60} D{sub 0}.
Date: March 30, 1967
Creator: Feola, J.M.; Richman, C.; Raju, M.R.; Curtis, S.B. & Lawrence, J.H.
Partner: UNT Libraries Government Documents Department

Berkeley Proton Linear Accelerator

Description: A linear accelerator, which increases the energy of protons from a 4 Mev Van de Graaff injector, to a final energy of 31.5 Mev, has been constructed. The accelerator consists of a cavity 40 feet long and 39 inches in diameter, excited at resonance in a longitudinal electric mode with a radio-frequency power of about 2.2 x 10{sup6} watts peak at 202.5 mo. Acceleration is made possible by the introduction of 46 axial "drift tubes" into the cavity, which is designed such that the particles traverse the distance between the centers of successive tubes in one cycle of the r.f. power. The protons are longitudinally stable as in the synchrotron, and are stabilized transversely by the action of converging fields produced by focusing grids. The electrical cavity is constructed like an inverted airplane fuselage and is supported in a vacuum tank. Power is supplied by 9 high powered oscillators fed from a pulse generator of the artificial transmission line type. Output currents are 3 x 10 {sup-9} ampere average, and 50 {mu}a peak. The beam has a diameter of 1 cm and an angular divergence of 10{sup-3} radians.
Date: October 13, 1953
Creator: Alvarez, L. W.; Bradner, H.; Franck, J.; Gordon, H.; Gow, J.D.; Marshall, L.C. et al.
Partner: UNT Libraries Government Documents Department