Nuclear reactions in linear medical accelerators and their exposure consequences

► Spectrometric analysis of linacs after 15, 18 and 20 MV beam emission was performed. ► Most intensively activated accelerator head elements are indicated. ► Assessment of H*(10) and distinguishing the isotopic contributions was performed. ► Induced activity increases not linearly with increasing of beam nominal potential. ► Doses in front of the collimators are up to 2 times higher than near the head casing.