A stochastic reaction–diffusion modeling investigation of FLASH ultra-high dose rate response in different tissues

Purpose: The aim of the study was to propose a theory based on topology and geometry diffusion channels in tissue contribute mechanistic understanding normal sparing at ultra-high dose rates (UHDRs) explore an interplay between intra- inter-track radical recombination through reaction–diffusion mechanism. Methods: We calculate time evolution particle track structures using system coupled equations random network designed for molecular transport porous disordered media. is representative inter-cellular tissues. Spatial cellular heterogeneities over scale spacing are constructed by incorporating fluctuations connectivity sites, resembling mass charge level. Results: demonstrate occurrence phase separation among tracks as complexity structure increases. At strong limit structural disorder, evolve individually like isolated islands with negligible they propagate localized waves space, analogous Anderson localization quantum mechanics. In contrast, weak disorder homogeneous medium, such water, neighboring melt into each other form percolated non-reactive species. Thus, spatiotemporal correlation chemically active domains vanishes increases from fractal-type malignancy. Conclusion: Differential FLASH may result proximity landscape, transition spatial distribution chemical reactivity, crowding. this context, insensitivities radiobiological responses tumors FLASH-UHDR interpreted via lack geometrical tracks. complexities cancerous cells prevent clustering timescale, which reactivities presumably prevail A series systematic experiments radiolysis-induced diffusivity reactivity actual tissues must be performed classify potentially spared FLASH-UHDRs verify our theory.