Preliminary estimation of the radiobiological response to carbon ion irradiation in silico and in vivo

This study addresses the radiobiological efficacy of carbon ion irradiation generated at the U-70 accelerator facility. Particular emphasis is placed on a comprehensive methodology that integrates computational (in silico) techniques based on the earlier developed software with in vivo experiments on laboratory animals with engrafted tumors. This dual approach refines the spatial-energy parameters of the ion beam, ensures accurate formation of the Bragg peak, and evaluates the contribution of secondary particles to the overall radiobiological impact. The aim of this study was to perform a comprehensive assessment of the relative biological effectiveness of the ion beam. The assessment was carried out using experimentally measured absorbed doses and direct observations of tumor growth dynamics following irradiation, in combination with specially developed mathematical and software tools for validating and predicting the radiation spectrum and linear energy transfer characteristics. The absorbed dose estimate during experimental studies performed using ionization chambers, placed inside the object positioning system. After the irradiation, which take place on the 12 days after the tumor implantation, during the follow up period the tumor growth dynamics was analyzed during 25 days. The findings revealed a high level of radiobiological response to carbon ion irradiation, primarily attributable to the increased linear energy transfer and extensive cluster damage to DNA. The experiments also underscored the necessity for stringent dosimetric control and careful consideration of individual biological variability when assessing therapeutic outcomes. Hence, the integration of modeling and in vivo experimentation provides deeper insights into the mechanisms by which heavy ions interact with biological systems, enhances predictive accuracy for treatment efficacy, and establishes a foundation for optimizing ion therapy protocols in oncology.