TABLE 2.

Irradiation Variables (r₀, T_i, T_d) and Fitted Linear-Quadratic Parameters (α, β) for Surviving Fraction of V79 and MDA-MB-231 Cells Irradiated with ¹³⁷Cs γ Rays

Dose-rate pattern	acute	exponential	chronic	chronic	chronic
Ti (h)*		0	2	8	24
Td (h)†		64	64	64	64
V79 Cells
Maximum r0 (cGy h−1)‡		33	38	50.5	95
α (Gy−1)	0.0396	0	0	0	0
β (Gy−2)	0.0222	0.0033	0.0021	0.0018	0.0014
α/β (Gy)	1.78
MDA-MB-231 Cells
Maximum r0 (cGy h−1)‡		16.8			29.6
α (Gy−1)	0.386	0.2962			0
β (Gy−2)	0.0378	0.0316			0.0406
α/β (Gy)	10.2

^*T_i = Dose rate increase half time.

^†T_d = Dose rate decrease half time.

^‡Maximum extrapolated initial dose rate corresponding to position closest to ¹³⁷Cs source. Dose-rate profiles for the lower positions in the irradiator are given in Supplemental Fig. 1 (http://dx.doi.org/10.1667/RR14766.1.S1).