Biophysical calculation of cell survival probabilities using amorphous track structure models for heavy-ion irradiation

Both the microdosimetric kinetic model (MKM) and the local effect model(LEM) can be used to calculate the surviving fraction of cells irradiated byhigh-energy ion beams. In this study, amorphous track structuremodels insteadof the stochastic energy deposition are used for the MKM calculation, and it isfound that the MKM calculation is useful for predicting the survival curves ofthe mammalian cells in vitro for 3He-, 12C- and 20Ne-ion beams. The survivalcurves are also calculated by two different implementations of the LEM, whichinherently used an amorphous track structure model. The results calculatedin this manner show good agreement with the experimental results especiallyfor the modified LEM. These results are compared to those calculated by theMKM. Comparison of the two models reveals that both models require threebasic constituents: target geometry, photon survival curve and track structure,although the implementation of each model is significantly different. In thecontext of the amorphous track structure model, the difference between theMKM and LEM is primarily the result of different approaches calculatingthe biological effects of the extremely high local dose in the center of the iontrack