Radiation protection strategies for FLASH radiotherapy accelerator installation in animal housing.

This study presents a radioprotection assessment for an ultra-high dose rate accelerator installation in one of the animal housing of the Centre for Advanced Preclinical in vivo Research. The main problem concerns the absence of a bunker while limiting exposure in nearby work areas. The geometry of the accelerator, the building layouts and the distribution of the environmental dose equivalent were simulated with FLUKA.CERN 4-4.1, modeling a 9 MeV electron beam. The results confirmed compliance with the limit of 0.250 mSv/year for unrestricted areas during daytime operation. Night-time operating zone restrictions apply when no staff are present, allowing beam on for quality controls. The effective doses to the population, researchers and workers are less than 1 mSv/year, in accordance with Legislative Decree 101/2020; the accelerator operators are classified as exposed. For small animals, precautionary dose limit of 1 mSv/year was adopted. The use of lead shielding and site-specific safety measures ensure radiological compliance.