Fig. 5

Clonogenic survival (top) of the Renca cells when exposed to various doses of a monoenergetic ⁴He ion beam at two measurements points. MC-estimated LET_d values are ~ 6 keV·μm⁻¹ at 6 mm depth (upper left) and ~ 15 keV·μm⁻¹ at 12 mm depth (upper right) using a ⁴He beam energy E = 56.65 MeV/u with a BP position (d_BP) of 25.9 mm. FLUKA-coupled biophysical and phenomenological models predicted cell survival and corresponding RBE (bottom) with varying degree of accuracy as a function of dose. The dotted and solid black line represent the LQ-fit of the Renca cells photon irradiation (γ) with (α/β)_x = 1.79 Gy and ⁴He irradiation, respectively