[Flash radiotheray at very high dose-rate: A brief account of the current situation]

In the last decade, major advances in high precision treatment delivery and multimodal imaging allowed radiotherapy to be more efficient and better tolerated. However, the technology of the accelerators used to generate X-ray beams is outdated and does not allow to explore the tolerance to novel approaches in terms of dose-rate. We have been the first to propose a completely novel modality of irradiation, named Flash radiotherapy, in which the dose per pulse and the instant dose-rate during the pulses is 10³ to 10⁴ higher than those used in conventional facilities. Flash has been shown to spare mouse lung from radio-induced fibrosis, whilst leaving unchanged the antitumor potential. Other teams have shown that the advantage of Flash in terms of reduced complications extends to normal brain and intestinal crypts. The goal of this paper is to review the progress of studies dealing with very high dose-rate "Flash" irradiation, describe the theoretical models proposed to explain the underlying mechanisms, and discuss the prospects for clinical applications of this emerging technique.