Fig. 5

RBE as a function of LET (a, b), depth (c, d) and fractional dose (e, f) including previous data for single and split doses [13,14,15]. For the experimental data, the LET-dependence was fitted by 2nd order polynomials while the dose-dependence was inter- and extrapolated with the LQ-model using the experimentally obtained α/β-ratios