Survival of cultured human cells exposed to californium 252Cf radiation at low dose rates

Abstract

HUMAN T-1 CELLS WERE USED TO DETERMINE THE RBE of low dose rate ²⁵²Cf (n + γ) radiation, compared to low dose rate gamma radiation. The T-1 cells were irradiated hypoxically at room temperature, and the dose rates were as follows: a) ²⁵²Cf (n + γ), 0.045, 0.090, and 0.270 Gy/hour; and b) ¹³⁷Cs gamma radiation, 0.117, 0 246, and 0.765 Gy/hour. The RBE was obtained as the ratio of the initial slope of the ¹³⁷Cs survival curves (approximately the same for all three dose rates), and the initial slope of the ²⁵²Cf survival curves (same for all three dose rates). The RBE was 5.0 ± 1.0 for all components of the ²⁵²Cf radiation and 7.1 ± 1.7 for the neutron components. As the dose increased, an inverse dose rate effect (more sensitive at lower dose rates) for the ¹³⁷Cs survival curves was observed.