The Br-nat(p,x)Se-73,Se-75 nuclear processes: a convenient route for the production of radioselenium tracers relevant to amino acid labelling

A possible route for the production of no-carrier-added (n.c.a.) Se-73 (T-1 /2 = 7.1 h) and Se-75 (120 d) is introduced.D,L-2-Amino-4-([Se-73]methyl-se leno) butanoic acid (D,L-[Se-73]selenomethionine) with an overall radiochem ical yield of > 40% could be prepared via a 3-step polymer-supported synthe sis after successful separation of Se-73 from KBr targets. Excitation funct ions for the Br-nat(p,x) Se-72,Se-73,Se-75 processes were measured from thr eshold up to 100 MeV utilizing pellets of pressed KBr. Targets were irradia ted at the NAC cyclotron with proton beams having primary energies of 40.4, 66.8 and 100.9 MeV. The calculated 73Se yield (EOB) for 1 h irradiation in 1 muA of beam at the optimum proton energy range of 62 --> 42 MeV is 81.4 MBq (2.2 mCi), and the calculated Se-75 yield (EOB) for the overall range 6 2 MeV --> threshold for the same irradiation conditions is 0.97 MBq (0.026m Ci). (C) 2001 Elsevier Science Ltd. All rights reserved.