FLASH radiotherapy: Considerations for multibeam and hypofractionation dose delivery response to van Marlen and colleagues

We thank our esteemed colleagues for their comments on our review on the possible difficulties in the implementation of FLASH [1]. It is apparent that FLASH has become the ‘hot’ topic for research in our field in a remarkably short time, as was noted by the topic’s dominance of the 2019 ASTRO survey, rising from relative obscurity in 2018 [2]. It was also apparent at the recent Flash Radiotherapy & Particle Therapy (FRPT) conference [3] that FLASH has rejuvenated a number of linked research areas in radiotherapy, and FLASH research may well bring unforeseen benefits in ultra-high dose rate (UHDR) and beyond.