ESTRO 2025 - Abstract Book

S3539

Physics - Optimisation, algorithms and applications for ion beam treatment planning

ESTRO 2025

experimental DSB yield of mammalian cells. The MMKM established an relation between the double strands break (DSB) and LET by introducing the f (LET) function, and therefore a variable β with LET. Although experimental data represent the dependence of the yield of primary lesions on the ion types, the DSB yield (assumed as the main primary lesion) is assumed independent of the ion species or cell lines in the MKM and MMKM. Here this work is to study the influence of cell line radiosensitivity on the microdosimetric kinetic model in carbon therapy for relative biological effectiveness calculation in treatment planning. Material/Methods: The experimental DSB yield under carbon radiation of different cell lines with different LETs was collected. The data was categorized into different cell lines. For each cell line, the RBE DSB (RBE for the induction of DSB)-LET curve is obtained through a least-square fitting procedure. Subsequently, the RBE DSB -LET curve is used to correct the primary lesion yield in the MKM, and the variation of primary lesion yield with LET was considered in the later calculation. The α and β values for mono-energetic and spread-out Bragg peaks (SOBP) of physical and clinical dose distributions was calculated by FLUKA for the MKM in this work under the irradiation of carbon ions. Results: By considering the yield of primary lesions as a function of the different cell lines, the α and β values are in better agreement with the experimental data as compared to those of the MKM and MMKM methods.

Conclusion: Besides the uncertainty associated in biological cell experiment. The dependence of the cell lines with respect to the RBE should be fully considered in the calculation model.