Understanding of FLASH radiotherapy through physical to biological interpretation

This study presents a unified framework, systematically shows a detailed visual representation and emphasizes the understanding via various key factors throughout physical-chemical-biological stages underlying the irradiation process in FLASH radiotherapy (FLASH-RT) from the review of previous published studies. To develop this framework, we pay close attention to the time scale of irradiation process, to incorporated methodologies from current hypotheses documented by in vitro and vivo studies. Concurrently, the framework illustrates the potential differences in tumor and normal cells induced by FLASH-RT. This synthesis of the literature reveals the potential research points in existing hypotheses which lack of consideration on the entire responses and interactions of each stage from initial physical to biological process. Our interpretation provides both a structured overview and a conceptual explanation, facilitating current understanding and further investigation that could be validated in future experimental settings in FLASH-RT research.