Excitation functions for the cyclotron production of 99mTc and 99Mo

Excitation functions for the 100Mo(p,2n)99mTc, 100Mo(p,pn)99Mo and 98Mo(p,γ)99mTc nuclear reactions were determined using 97.4 and 99.5% isotopic enrichment of 100Mo and 98Mo, respectively. The irradiations were performed on three different cyclotrons with overlapping data points from 6 to 65 MeV. The optimum energy range for the 100Mo(p,2n)99mTc reaction is 22→12 MeV with a peak at not, vert, similar17 MeV and maximum cross section of not, vert, similar200 mb. Over this energy range the production yield of 99mTc amounts to 11.2 mCi (415 MBq)/μA h or 102.8 mCi (3804 MBq)/μA at saturation. There is no serious radionuclidic impurity problem. Production of 99Mo is not viable due to the low cross section (not, vert, similar130 mb) over the proton energy range of 30 to 50 MeV. The 98Mo(p,γ)99mTc reaction was found to have a cross section of <0.2 mb over the proton energy range studied. The earlier assignment of this reaction channel as a potential route for production of 99mTc with a medical cyclotron is refuted in this study. Countries that do not have access to fission molybdenum-99 for the 99Mo→99mTc generator, could consider use of a >17 MeV proton energy cyclotron for regional production of 99mTc.