FLASH from the past.
This study describes conversion (with very detailed instructions) of a Varian 2100 C/D LINAC to deliver a FLASH-RT dose rate with electrons. They used the 10 MV photon mode, but removed the target, flattening filter, and scattering foil. Photon generation from a target is inefficient, which means the electron beam in photon mode is intense. At room isocenter, the LINAC was able to generate a pulsed beam output of > 200 Gy/s. But that’s not all. The conversion took less than half an hour and the LINAC could still be switched back to clinical mode without any permanent modifications. | Rahman, Int J Radiat Oncol Biol Phys 2021