Spectral Comparison of Neutron-Irradiated Natural and Enriched Ytterbium Targets for Lu-177 Production

Abstract

Beta-emitting radioisotope ¹⁷⁷Lu has been suggested for radioimmunotherapy, peptide receptor radionuclide therapy, or another radionuclide therapy due to its excellent properties for destroying cancer cells. In this experimental investigation, natural ytterbium (^natYb) and enriched ¹⁷⁶Yb targets were irradiated with thermal neutrons at 1.2×10¹⁴ cm^-2s^-1 neutron flux for 95 hours. Using a high-purity germanium (HPGe) detector-based spectroscopy system, the post-irradiated targets were measured and the produced radioisotopes were identified according to their gamma ray emissions. Experimental results indicated that several radioisotopes such as ¹⁶⁹Yb and ¹⁷⁵Yb dominate the post-irradiated ^natYb target, though a relatively weak intensity of ¹⁷⁷Lu was also recorded. In contrast, ¹⁷⁷Lu radioisotope dominates the gamma rays observed in the post-irradiated enriched ¹⁷⁶Yb target following elution with HNO₃ solution. For the first time, evidence is found of ¹⁷⁵Yb impurity in the post-neutron-irradiated enriched ¹⁷⁶Yb₂O₃ target as a result of ¹⁷⁶Yb(n,2n)¹⁷⁵Yb nuclear reaction. This work recommends future ¹⁷⁷Lu radioisotope production using enriched ¹⁷⁶Yb₂O₃ target.