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

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).