Measurement of the Production Cross Sections of $\beta ^{+}$ Emitters for Range Verification in Proton Therapy

Abstract

In proton therapy, there is an intensive research program aiming at in vivo range verification in order to reduce the uncertainties in the range of the proton beam, that limit the benefits of having a sharp Bragg peak [1]. In-vivo PET range verification relies on the comparison of the measured and estimated activity distributions of $\beta ^{+}$ emitters induced on C, N, O, Ca and P by the protons along the body of the patient. As the accuracy of the estimated distribution depends on the underlying cross sections data [2], a revision of the experimental data available has been done, showing that they are not always available in the full energy range of interest (up to 250 MeV) and that there are sizeable differences in some cases [3]. The aim of this study is to develop a method for measuring the production cross sections of the $\beta ^{+}$ emitters up to 250 MeV. For this, as starting point, the production cross sections of $^{11}$C and $^{13}$N in $^{nat}$C, $^{nat}$N and $^{nat}$O have been measured at Bragg peak energies using the 18 MeV proton beam at the CNA cyclotron and a multi-layer target configuration. The activity induced in each film has been measured using the clinical PET scanner at CNA.