Editorial: Multidisciplinary approaches to the FLASH radiotherapy

While these rapidly accumulating results indicate bright prospects, the clinical translation is still in its early phase, due to different challenges. First, several technological issues must be addressed to design new stable radiation sources capable of delivering beams with fluences orders of magnitude higher than those of conventional RT, and with a reliable real time beam monitoring system. This also implies the need of new dosimetric protocols, since most of the active dosimeters used for conventional beams do not respond accurately to UHDR and ultra high dose-per-pulse (UHDP) 3 , 4 . Accurate dosimetry is not only needed for clinical implementation, but also for more robust and reproducible pre-clinical experiments 5 . The second challenge is understanding the biological mechanism underlying the FLASH effect, to explain the differential response of cancer vs normal tissues. Several hypotheses have been considered, involving the whole cascade from the early radiation chemistry events to the classical radiation-induced molecular and cellular mechanisms and tissue recovery processes, also including a are the first step to proceed towards a deeper knowledge of the phenomenon and towards its optimal 98 clinical implementation.