Survival fractions of melanoma B16 cells at different penetration depths exposed to 49.30MeV/u 12 C ion beam and modulated 74.55MeV/u 12 C ion beam with a ridge filter to form a spread-out Bragg peak (SOBP) were measured. The results show the survival response of B16 cells as the biological endpoint to heavy ions increases synchronously with the deposited energy along the beam traversal

that is

the survival fraction near or at the Bragg peak or SOBP is far lower than that at the beam’s entrance or exit channel. Comparisons of the experimental data with calculated survival fractions at different depths predicted by the linear-quadratic survival model combined with dose-averaged LET display a good agreement within the experimental errors. It is prompted that the linear-quadratic model combined with dose-averaged LET possibly is a valid way to calculate the survival effect of B16 cells along the beam penetration under the exposure of the intermediate energy heavy-ion beam.