Production and Quality Control of 175Yb-EDTMP for Pain Palliation of Bone Metastases

Bone metastasis is a major consequence of several cancers. The prostate, breast, lung cancers are mostly associated with the bone pain. Different radioisotopes are used for the bone pain palliation. 175Yb is proposed as a proper alternative to other radioisotopes due to its relatively long half-life (T1/2=4.18 days), maximum energy beta particle Eβ-=470 keV (86%), low abundance gamma emission, low cost, and easy production. In this study, 175Yb was obtained by thermal neutron bombardment of a natural 174Yb2O3 sample in the 5MW Tehran Research Reactor (TRR). The radionuclide purity of the 175Yb was ascertained by recording gamma ray spectra using a gamma spectrometer with a HPGe detector. Radiolabeling was completed in one hour by the addition of EDTMP at room temperature and pH=8-9. The quality control and biodistribution studies were carried out in normal wild-type rats. The radiochemical purity was determined by ITLC and the results were found to be higher than 99%. This study showed favorable biodistribution features of 175Yb-EDTMP which are indicating its significant accumulation in the bone. Also, it was observed that clearance of the activity from other organs accrued after 4 days. This research presents 175Yb-EDTMP as a suitable radiopharmaceutical with a proper half-life and low dose for the bone palliation of skeletal metastases.