Tissues differential sparing of FLASH ultra-high dose rate: an in-silico radiotherapy study

The study aims to understand the role of cellular microstructures and vasculature in human normal and malignant tissues and their correlations to the biological responses at FLASH ultra-high dose rate (UHDR) radiotherapy. The latter plays the role of oxygen effect in normoxic and hypoxic tissue environment and oxygen depletion effect at UHDR. We fit the current experimental and clinical data available in the literature to propose a theory based on the topology and geometry of diffusion channels in tissue to contribute to the mechanistic understanding of normal tissue sparing at UHDRs and explore an interplay between intra- and inter-track radical recombination through a reaction-diffusion mechanism.