A 140Nd/140Pr radionuclide generator based on physico-chemical transitions in 140Pr complexes after electron capture decay of 140Nd-DOTA

Abstract

140Nd was produced by irradiations of CeO2 and Pr2O3 targets leading to natCe(3He,xn) 140Nd and 141Pr(p,2n) 140Nd nuclear reactions. The practical yield of 140Nd at EOB in the former reaction over the energy range of E 3He = 33.5 → 0 MeV amounted to 3.5 MBq/μA h and in the latter reaction over the energy range of E p = 18.6→16.2 MeV to 15.5 MBq/μA h. These values correspond to about 41% and 60% of the respective theoretical values. Successful separations of the radionuclide were performed by means of cation-exchange chromatography resulting in decontamination factors of ≥108 and ≥7×105 for the cerium and praseodymium target materials, respectively. With the no-carrier-added 140Nd obtained, an efficient 140Nd/140Pr radionuclide generator system was developed and evaluated. The principle of the radiochemical separation is based on physico-chemical transitions (hot-atom effects) of the daughter 140Pr following the electron decay process of 140Nd. The parent radionuclide 140Nd(III) is quantitatively adsorbed on a solid phase matrix in the form of 140Nd-DOTA-conjugated complexes. The daughter nuclide 140Pr is generated in an ionic species and is easily separated using low volumes of various aqueous eluents. The elution yield is at least 93%, if an optimized eluent, such as DTPA solution is applied. The system remains stable at least over three half-lives of 140Nd, with high radiolytic stability and low 140Nd breakthrough. This radionuclide generator system 140Nd (T 1/2 = 3.37 d) provides the short-lived positron-emitting radiolanthanide 140Pr (T 1/2 = 3.4 min) for molecular imaging using positron emission tomography (PET).