VHEE High Dose Rate Dosimetry Studies in CLEAR

The 200 MeV electron beam of the CERN Linear Accelerator for Research (CLEAR) user facility at CERN has been intensively used to study the potential use of Very High Energy Electrons (VHEE) in cancer radiotherapy. In particular, irradiation tests have been performed in the high dose rate regime, which has gained a lot of interest for the so called FLASH biological effect, in which cancer cells are damaged while healthy tissue is largely spared. High dose rate dosimetry, though, poses a number of challenges: to validate standard or new methods of passive dosimetry, like radiochromic films and alanine pellets, and especially to develop new methods for real-time dosimetry since the normally used ionization chambers suffer from non-linear effects at high dose rates. In this paper we describe the results of experimental activities at CLEAR aimed at developing solid, high-dose rate dosimetry standards adapted to VHEE beams.