ANALYSIS OF CELL-SURVIVAL FRACTIONS FOR HEAVY-ION IRRADIATIONS BASED ON MICRODOSIMETRIC KINETIC MODEL IMPLEMENTED IN THE PARTICLE AND HEAVY ION TRANSPORT CODE SYSTEM

作者：Sato T^*; Watanabe R; Kase Y; Tsuruoka C; Suzuki M; Furusawa Y; Niita K

来源：Radiation Protection Dosimetry, 2011, 143(2-4): 491-496.

DOI：10.1093/rpd/ncq484

It is considered that the linear energy transfer (LET) may not be the ideal index for expressing the relative biological effectiveness (RBE) of cell killing for heavy-ion irradiation, as the ion-species dependencies have clearly been observed in the relation between LET and RBE derived from cell-survival fraction data. The previously measured survival fractions of four cell lines irradiated by various ion species, employing the saturation-corrected dose-mean lineal energy, y*, instead of LET as the index of the RBE were therefore re-analysed. In the analysis, the initial slopes of the survival fractions, the so-called alpha-parameter in the linear-quadratic model, were plotted as a function of y*, which was calculated by the microdosimetric kinetic (MK) model implemented in the Particle and Heavy Ion Transport code System. It was found from the analysis that the ion-species dependencies observed in the relations between a and LET disappeared from those between a and y*, and their relations can be well reproduced by a simple equation derived from the MK model. These results clearly indicate the suitability of y* to be used in the estimation of the RBE of cell killing for heavy-ion irradiations, which is of great importance in the treatment planning of charged-particle therapy.

• 出版日期2011-2