Kase, Y., Kanai, T., Matsumoto, Y., Furusawa, Y., Okamoto, H., Asaba, T., Sakama, M. and Shinoda, H. Microdosimetric Measurements and Estimation of Human Cell Survival for Heavy-Ion Beams. Radiat. Res. 166, 629–638 (2006).

The microdosimetric spectra for high-energy beams of photons and proton, helium, carbon, neon, silicon and iron ions (LET = 0.5–880 keV/μm) were measured with a spherical-walled tissue-equivalent proportional counter at various depths in a plastic phantom. Survival curves for human tumor cells were also obtained under the same conditions. Then the survival curves were compared with those estimated by a microdosimetric model based on the spectra and the biological parameters for each cell line. The estimated α terms of the liner-quadratic model with a fixed β value reproduced the experimental results for cell irradiation for ion beams with LETs of less than 450 keV/μm, except in the region near the distal peak.