TABLE 3.

Parameters for Chromosome Exchange and Breakpoint Doses Response Fits

Damage parameter	Cell, radiation	Model*	α (D)	β (D2)	c (Intercept)
Simple exchanges	Fibroblasts γ rays	α/β	0.20 ± 0.05	0.03 ± 0.01	0.03 ± 0.04
	Lymphocytes γ rays	α/β	0.27 ± 0.10	0.04 ± 0.02	−0.004 ± 0.080
	Fibroblasts α particles	Linear	2.02 ± 0.16		0.07 ± 0.04
	Lymphocytes Fe ions	Linear	0.53 ± 0.02		0.02 ± 0.02
Complex exchanges	Fibroblasts γ rays	Quadratic		0.012 ± 0.001	0.002 ± 0.005
	Lymphocytes γ rays	Quadratic		0.037 ± 0.002	−0.007 ± 0.001
	Fibroblasts α particles	Linear	0.75 ± 0.09		0.009 ± 0.021
	Lymphocytes Fe ions	Linear	0.40 ± 0.02		−0.01 ± 0.02
Complex chromosome breakpoints	Fibroblasts γ rays	Quadratic		0.038 ± 0.003	0.01 ± 0.02
	Lymphocytes γ rays	Quadratic		0.17 ± 0.01	−0.07 ± 0.09
	Fibroblasts α particles	Linear	2.70 ± 0.32		0.015 ± 0.074
	Lymphocytes Fe ions	α/β	0.53 ± 0.31	1.16 ± 0.20	0.10 ± 0.09

^*By standard practice, we have fit the γ-ray data to linear-quadratic (α/β) models even though such models failed to provide a significantly better fit to the data than simple linear ones. The γ-ray responses for complex exchange breakpoints, however, were fit by pure quadratic models since linear-quadratic fits returned negative α coefficients.