β+ Radioactive Nuclei Created During Proton Therapy

Abstract

During proton therapy, the beam flux decreases due to inelastic interactions with nuclei. At the highest energies used in proton therapy, around 20% protons initiate nuclear reactions. This report presents the cross-section measurements of proton-induced production of three β⁺ emitters — ¹¹C, ¹³N, ¹⁵O — with half-lives between 2 and 20 min, using solid C, BN, and SiO₂ targets. Stacks of up to 15 targets were irradiated simultaneously with proton beams of kinetic energy below 58 MeV at the AIC-144 cyclotron of the Institute of Nuclear Physics, Polish Academy of Sciences. The measured cross sections follow the excitation function obtained in the previous experiments, with uncertainty of a few percent.