Deuteron cyclotron production studies of high specific activity Lu-177g in NCA form for metabolic radiotherapy

The 177(m+g)Lu is normally produced in carrier-added (CA) form by (n,gamma) reaction on enriched 176Lu target in thermal nuclear reactor, with a lower specific activity AS than the theoretical carrier-free one, i.e. AS(CF) = 4.05 GBq.microg-1. Alternatively, it can be produced in no-carrier-added form (NCA), by either neutron activation on enriched 176Yb target or by deuteron irradiation on very highly enriched 176Lu target, followed by negatron decay. In both cases an AS value very close to the CF one is achievable after selective radiochemical separation of 177Lu from Yb target. It is remarkable that 177Yb decays solely to the ground level of 177Lu, leading to a very high radionuclidic purity 177gLu, not contaminated by the long-lived metastable level 177mLu. The attention is focused on 177gLu due to its remarkable applications in metabolic radiotherapy of tumors, due to the pretty low “average” negatron energy of 163 keV and the emission of gamma rays at 208 and 113 keV, suitable for detection of biodistribution by both gamma-camera and SPET.