title: Analysis of cell-survival fractions for heavy-ion irradiations based on microdosimetric kinetic model implemented in the particle and heavy ion transport code system.
abstract: 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 α-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 α and LET disappeared from those between α 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.
authors.affiliation: Japan Atomic Energy Agency, Shirakata-Shirane 2-4, Tokai, Ibaraki 319-1195, Japan. sato.tatsuhiko@jaea.go.jp
authors.forename: T
authors.initials: T
authors.lastname: Sato
authors.forename: R
authors.initials: R
authors.lastname: Watanabe
authors.forename: Y
authors.initials: Y
authors.lastname: Kase
authors.forename: C
authors.initials: C
authors.lastname: Tsuruoka
authors.forename: M
authors.initials: M
authors.lastname: Suzuki
authors.forename: Y
authors.initials: Y
authors.lastname: Furusawa
authors.forename: K
authors.initials: K
authors.lastname: Niita
mesh_terms: D002470:Cell Survival / Q000528:radiation effects*; D003198:Computer Simulation; D020450:Heavy Ions; D018499:Linear Energy Transfer / Q000502:physiology*; D008954:Models, Biological; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D012984:Software