"Researchers from Dartmouth have developed a method to convert a standard clinical linear accelerator (linac) used for radiation therapy to deliver a FLASH-capable, ultrahigh-dose rate (UHDR) radiotherapy beam. The process, which uses existing accessories, takes only 20 minutes to perform, or to reverse," reports Physics World.

"UHDR radiotherapy delivers radiation at dose rates that are hundreds, or even thousands, times higher than used in conventional treatments, leading to a phenomenon commonly referred to as the FLASH effect. Adapting a linac to deliver radiation at 300 Gy/s rather than 0.1 Gy/s enables treatment to be completed in 6 ms instead of 20 s. Crucially, preclinical research with laboratory animals has shown that these high dose rates significantly reduce toxicities to surrounding healthy tissue while maintaining anti-tumour activity.

"'We believe this is the first reversible UHDR beam on a clinically used linac where the beam can be used in the conventional geometry where patients are on the treatment couch,' says Brian Pogue, of the Thayer School of Engineering and the Norris Cotton Cancer Center.

"Writing in the International Journal of Radiation Oncology, Biology, Physics, Pogue and colleagues describe the procedures and guidelines that they developed to deliver UHDR to a treatment room isocentre."