Open AccessDetermining the parameter space for effective oxygen depletion for FLASH radiation therapy
Author(s) -
Bethany C. Rothwell,
N.F. Kirkby,
Michael J. Merchant,
Amy L. Chadwick,
Matthew Lowe,
Ranald I Mackay,
Jolyon H Hendry,
Karen J Kirkby
Publication year - 2021
Publication title -
physics in medicine and biology/physics in medicine and biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.312
H-Index - 191
eISSN - 1361-6560
pISSN - 0031-9155
DOI - 10.1088/1361-6560/abe2ea
Subject(s) - flash (photography) , radioresistance , radiation , oxygen , oxygen enhancement ratio , irradiation , radiobiology , dose rate , biological system , diffusion , radiation therapy , biophysics , computer science , materials science , radiochemistry , chemistry , physics , biology , optics , medicine , thermodynamics , nuclear physics , organic chemistry
There has been a recent revival of interest in the FLASH effect, after experiments have shown normal tissue sparing capabilities of ultra-high-dose-rate radiation with no compromise on tumour growth restraint. A model has been developed to investigate the relative importance of a number of fundamental parameters considered to be involved in the oxygen depletion paradigm of induced radioresistance. An example eight-dimensional parameter space demonstrates the conditions under which radiation may induce sufficient depletion of oxygen for a diffusion-limited hypoxic cellular response. Initial results support experimental evidence that FLASH sparing is only achieved for dose rates on the order of tens of Gy s -1 or higher, for a sufficiently high dose, and only for tissue that is slightly hypoxic at the time of radiation. We show that the FLASH effect is the result of a number of biological, radiochemical and delivery parameters. Also, the threshold dose for a FLASH effect occurring would be more prominent when the parameterisation was optimised to produce the maximum effect. The model provides a framework for further FLASH-related investigation and experimental design. An understanding of the mechanistic interactions producing an optimised FLASH effect is essential for its translation into clinical practice.