Quantitative assessment of the production of radioactive materials by the Mevion S250i Hyperscan proton therapy system: a year-long survey

Introduction: This technical note describes a quantitative assessment of the production of radioactive materials during a year-long clinical operation of a Mevion S250i Hyperscan proton therapy system. The production of accumulated radioactive materials plays an important role in determining radiation safety in and around the proton therapy facilities. Methods: We have conducted a weekly room survey, every week for a year, during normal clinical operation. Results and conclusions: We estimated the accumulated activity from secondary neutron activation on aluminium structures at 3 m away from isocentre in the beamline to be less than 300 μCi.