Validating production of PET radionuclides in solid and liquid targets: Comparing Geant4 predictions with FLUKA and measurements

The Monte Carlo toolkit Geant4 is used to simulate the production of a number of positron emitting radionuclides: $^{13}$N, $^{18}$F, $^{44}$Sc, $^{52}$Mn, $^{55}$Co$^{61}$Cu, $^{68}$Ga, $^{86}$Y, $^{89}$Zr and $^{94}$Tc, which have been produced using a 13 MeV medical cyclotron. The results are compared to previous simulations with the Monte Carlo code FLUKA and experimental measurements. The comparison shows variable degrees of agreement for different isotopes. The mean absolute deviation of Monte Carlo results from experiments was $1.4 \pm 1.6$ for FLUKA and $0.7 \pm 0.5$ for Geant4 using TENDL cross sections with QGSP-BIC-AllHP physics. Both agree well within the large error, which is due to the uncertainties present in both experimentally determined and theoretical reaction cross sections. Overall, Geant4 has been confirmed as a tool to simulate radionuclide production at low proton energy.