Irradiation in a flash: Unique sparing of memory in mice after whole brain irradiation with dose rates above 100 Gy/s

High dose‐per‐pulse electron beam dosimetry: Commissioning of the Oriatron eRT6 prototype linear accelerator for preclinical use

“…This enables using the beam monitoring system for documenting the actual dose delivered during each animal exposure. The Oriatron eRT6 linac is nowadays in full operation and preclinical irradiation studies with accurate dosimetry are being performed …”

Radiation, inflammation and the immune response in cancer

“…Thoracic IR of mice using 15 Gy conventional X-ray (DR 1.8 Gy/min) or 20 Gy Flash RT (DR > 2400 Gy/min; pulse rate < 500 ms) provided comparable lung tumour control, but Flash RT produced fewer fibrotic lesions (Favaudon et al 2014). In a similar study, 10 Gy murine whole brain FLASH RT (DR > 6000 Gy/min; pulse rate 1 µs) preserved spatial memory and hippocampal neurogenesis when compared to conventional RT (6 Gy/min) (Montay-Gruel et al 2017). The effect was absent if DR < 1800 Gy/min were used.…”

FLASH radiotherapy: Newsflash or flash in the pan?

“…The phenomenon of the increased therapeutic index of FLASH compared to conventional dose rate irradiation, or the “FLASH effect,” has now been reported in multiple preclinical models. Normal tissue sparing by FLASH of multiple organ systems including lung, brain, intestinal tract, and skin has been demonstrated in multiple mouse strains and even additional species (cat and mini‐pig), while demonstrating an equivalent (and in some cases superior) tumoricidal effect relative to conventional dose‐rate delivery in multiple in vivo tumor models . Given the nascent state of the field, a large portion of experimental observations to date remain preliminary and unpublished, and many questions remain unanswered particularly with respect to mechanism.…”

“…The FLASH effect is also incompletely characterized even from a phenomenological standpoint. Evidence to date suggests that a dose rate threshold of approximately 40 Gray/s or higher is needed to produce the FLASH effect . However, the accelerator‐based radiation delivery systems used for FLASH experiments to date produce pulsed radiation, and there are many aspects of delivery speed, for example, total dose and delivery time, dose per pulse, pulse timing structure, etc., that may be critical to the effect and have not been comprehensively evaluated, since an exhaustive study is an experimentally daunting combinatorial problem.…”