Measurement and Protection of Induced Radioactivity in Proton Heavy Ion Accelerator Therapy

Proton-heavy ion therapy is internationally recognized as the most advantageous radiotherapy method in oncology. However, due to the relatively high energy of the proton-heavy ion beams, the secondary neutrons produced in the process of beam energy loss activate the surrounding materials and generate induced radioactivity, which is a threat to the health of staff and patients. Therefore, it is necessary to pay attention to the related radiation protection. In this paper, the causes and distribution of induced radioactivity were explored. We estimated the energy distribution and radiation dosages of the secondary neutrons produced in proton-heavy ion therapy by performing measurements and MCNPX (Monte Carlo) simulations, and we also detected the radiation dosages of the induced radioactivity varying with time after irradiation. Finally, we discussed the effective radiation protection measures with the aim to reduce and avoid the health hazards from induced radioactivity to the staff and patients and provide practical guarantee for the safety and effectiveness of proton-heavy ion therapy.