alt Hacker NewsThe major issue isn't the speed of delivery, and the cancer.
The key question is how do you spare normal tissue, and how do you prove the normal tissue is spared in the long term. Current answer is: You break it apart into multiple sessions, the anti-thesis of FLASH.
Source: my wife is a radiation oncologist.
from the article (pay attention to the part in italics):
FLASH radiotherapy flips the conventional approach on its head, delivering a single dose of ultrahigh-power radiation in a burst that typically lasts less than one-tenth of a second. In study after study, this technique causes significantly less injury to normal tissue than conventional radiation does, without compromising its antitumor effect.