Production of high specific activity NCA Lu-177g by cyclotron irradiation

Lu-177g is a low energy negatron emitter that thanks to its favourable decay properties (T1/2=6.734 d, negatron emission 100 %, E(beta,max)=489.3 keV, < E(beta) >=163 keV, E(gamma)=208.4 keV) is one of the most promising RNs to be used in nuclear medicine, especially in metabolic radiotherapy of cancer of small dimensions. The production of Lu-177g is carried out mainly in thermal nuclear reactor in two different ways by using targets of Lu or Yb: in the first case Lu-177(m+g) is produced in carrier-added (CA) form by (n,gamma) reaction on enriched target of Lu-176 leading to a lower specific activity AS compared to the theoretical carrier-free value AS(CF) = 4.05 GBq/microg, while in the second case Lu-177g is produced in no-carrier-added (NCA) form by (n,gamma) reaction on enriched target of Yb-176 followed by negatron decay leading, after selective separation of Lu from Yb, to a higher AS than in the previous case. This latter case shows no evidence of production of the long-lived impurity Lu-177m. As an alternative method is to produce Lu-177 by the deuteron activation of natural Yb or enriched in Yb-176 targets. In this case , with the following routs of interest are the indirect reaction Yb-176(d,p)Yb-177 that decays by negatron emission to Lu-177g and a much smaller contribution of the direct reaction Yb-176(d,n)Lu-177(g+m).