Comparative Effects of Bremsstrahlung, Gamma, and Electron Radiation on Rat Motor Performance,
ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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The effects of rapidly delivered supralethal doses of bremsstrahlung, electron, and gamma radiation were investigated on the performance of male Sprague Dawley rats exposed at a midline tissue dose MTD rate of 2000 radmin. The bremsstrahlung and electron radiations were produced in a linear accelerator LINAC, and the gamma radiation was produced in a 60 CO facility. Relative radiation effects were determined by establishing median effective doses ED50 for rats trained on the accelerod, a shock-avoidance test of motor performance. ED50s were based on 10-min post-exposure performance. The ED50 was 8121 rad for the bremsstrahlung field, 6110 rad for the electron radiation, and 3896 rad for the gamma photons. No significant difference was found between the bremsstrahlung and gamma radiations even though the physical characteristics used to achieve the two fields were less uniform in the bremsstrahlung exposures. However, the other ED50s translate into significantly different relative effectiveness of 1.35 between the bremsstrahlung and electron fields, and 1.45 between the electron and gamma radiations. The data imply that different radiation fields are not equally effective on behavior.