Determining the boundaries of the FLASH effect
Rothwell, Bethany C Chadwick, Amy Lowe, Matthew
Rothwell, Bethany C
Chadwick, Amy
Lowe, Matthew
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Abstract
Purpose or Objective
Ultra-high dose rate, or ‘FLASH’, radiotherapy is an area
of worldwide interest, after studies have demonstrated
normal-tissue-sparing advantages over conventional
irradiation, while apparently retaining tumour control1.
Currently, there is a distinct lack of understanding of the
underlying mechanisms behind this effect. Many early
reports have discussed radiation-induced oxygen depletion
as a possible explanation for normal-tissue sparing, but
this still needs further investigation. There is a wealth of
knowledge of the radiobiological effects of hypoxia which
can be used to explore this hypothesis further. This work
is aimed at determining whether oxygen depletion can
feasibly explain the normal-tissue-sparing effect of FLASH.
Material and Methods
Cellular automata techniques have been employed to solve
a model of oxygen diffusion and consumption in cells, and
to investigate how these are affected by ultra-high-doserate
irradiation.
Results
A biologically-relevant parameter space has been
identified in which, to a first approximation, FLASH
radiation depletes sufficient oxygen for a transient hypoxic
response. Conclusion
Thresholds for a number of parameters, including dose and
dose rate, have been determined for a feasible FLASH
effect caused by oxygen depletion, which can be used as a
starting point for experimental verification. The
development of a full mechanistic understanding of the
FLASH effect is essential for its translation into a clinical
setting.
Description
Date
2020
Publisher
Collections
Keywords
Type
Meetings and Proceedings
Citation
Rothwell B, Kirkby N, Merchant M, Chadwick A, Lowe M, Mackay R, et al. PO-1810: Determining the boundaries of the FLASH effect. Radiotherapy and Oncology . 2020 Nov;152:S1009–10.