Table I.

Fitting parameters, SF2 and RBE (2 Gy, γ) for 59M and HTB140 cells after irradiation with γ-rays and protons

Irrad. type	α(Gy–1)	r2	Fit Std. Err.	SF2	RBE (2 Gy, γ)
59M
γ-Rays	0.043 ±0.012	0.92	0.06	0.91 ±0.01	1.00
Protons	0.101 ±0.015	0.89	0.10	0.81 ±0.01	2.47 ±0.22
HTB140
γ-Rays	0.036 ±0.009	0.93	0.05	0.93 ±0.01	1.00
Protons	0.073 ±0.012	0.80	0.12	0.86 ±0.01	2.08 ±0.36

r² – coefficient of determination = 1 – sum of squares about the mean/sum of squared errors. Results are presented as the mean ± standard deviation