Estimations of fluorine-18 production yields from 13-MeV proton bombardment of enriched water target

Abstract

Fluorine-18 (18F) is a positron emitter frequently used in Positron Emission Tomography (PET) to assist in the staging of primary tumors, Recent research suggests that the positron emitting radionuclide can also be applied for pneumonia imaging caused by Covid-19 infection. In this work, a 13-MeV proton beam was theoretically bombarded to 99.5% enriched water (H2 18O) target to produce 18F radionuclide via (p, n) nuclear reaction. The CalcuYield code was used in the predictions of the F-18 production yields. Using the CalcuYield code, the 18F radioactivity yields were calculated at the end of bombardment (EOB) at various proton beam currents, irradiation time and proton beam doses. Based on the CalcuYield calculated results, the maximum EOB yield of 18F at 13 MeV proton energy was 60.073 mCi/µAh. At a proton dose of 60 µAh, the EOB yield could be achieved as high as 3784.393 mCi, which could be used to diagnose more than 500 patients. The calculations also found that for the same proton dose, increasing proton beam current would result in greater 18F radioactivity yield than increasing irradiation time. In addition, radionuclide impurities which could predictably be present in the target were mostly due to nuclear reactions between proton beam and havar window. The predicted radionuclide impurities include 96Tc, 55Fe, 59Ni, 56Co, 52Mn, 186Re and 58Cu which were due to (p, n) nuclear reactions. The total radionuclide impurity yield was found to be 0.793 mCi/µAh. Among the other impurities, 58Cu was expected to have the highest radioactivity yield at all irradiation parameters. These predicted results could be used as a reference for future 18F radionuclide production should a 13-MeV proton beam is employed.