$\beta^+$ 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 25\% protons initiate nuclear reactions. This report presents the cross section measurements of proton-induced production of three $\beta^+$ emitters -- $^{11}$C, $^{13}$N, $^{15}$O -- with half-lives between 2 and 20 minutes, using solid C, BN and SiO$_2$ 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.