$\beta^+$ radioactive nuclei created during proton therapy

TL;DR

This study measures the cross sections of proton-induced production of $eta^+$ emitters during proton therapy, providing data crucial for understanding dose delivery and nuclear interactions at therapeutic energies.

Contribution

It provides new experimental cross section data for $^{11}$C, $^{13}$N, and $^{15}$O production at energies relevant to proton therapy, with high precision.

Findings

Cross sections follow previous excitation functions with a few percent uncertainty.

Proton energies below 58 MeV produce measurable $eta^+$ emitters.

Data supports improved modeling of nuclear reactions in 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.