While neutron activation of natural Tm₂O₃ is the convenient strategy for producing ¹⁷⁰Tm for use in palliative care of painful bone metastases, the coproduction of ¹⁷¹Tm (t_1/2 = 1.92 years) is as an impediment towards its clinical utility. The production strategy has been optimized to obtain ¹⁷⁰Tm with adequate specific activity and radionuclidic purity. Preliminary clinical studies carried out using the ¹⁷⁰Tm-labeled ethylenediaminetetramethylene phosphonic acid (¹⁷⁰Tm-EDTMP) showed site specific localization of the radiopharmaceutical in skeleton with preferential accumulation in metastatic lesions along with almost no accumulation in non-target organs, a distribution pattern comparable to that of ^99mTc-labeled methylene diphosphonate (^99mTc-MDP).