Preparation of high specific activity ⁸⁶Y using a small biomedical cyclotron

⁸⁶Y is an attractive PET radionuclide due to its intermediate half-life. ⁸⁶Y was produced via the ⁸⁶Sr(p,n) ⁸⁶Y nuclear reaction. Enriched SrCO₃ or SrO was irradiated with 2-6 μA of beam current for <4 h on a CS-15 cyclotron. It was shown that the SrO target could withstand at least 6 μA of beam current, a significant improvement over a maximum of 2 μA on the SrCO₃ target. Average yields of 4.5 mCi/μA•h were achieved with SrO, which represent 71% of the theoretical yield, compared to 2.3 mCi/μA•h with SrCO₃. The radioisotopic contaminants were ^86mY (220%), ⁸⁷Y (0.27%), ^87mY (0.43%) and ⁸⁸Y (0.024%). ⁸⁶Y was isolated in an electrochemical cell consisting of three Pt electrodes. The solution was electrolyzed at 2000 mA (40 min) using two Pt plate electrodes. A second electrolysis (230 mA for 20 min) was performed using one Pt plate and a Pt wire. On average, 97.1% of the ⁸⁶Y was recollected on the Pt wire after a second electrolysis. The ⁸⁶Y was collected from the Pt wire using 2.8 M HNO₃/EtOH (3:1). After evaporation, ⁸⁶Y was reconstituted in 100 μl of 0.1 M HCl. Target materials were recovered as SrCO₃ and then converted to SrO by thermal decomposition at 1150°C. Specific activity of ⁸⁶Y was determined to be 29±19 mCi/μg via titration of ⁸⁶Y(OAc)₃ with DOTA or DTPA. We have established techniques for the routine, economical production of high purity, high specific activity ⁸⁶Y on a small biomedical cyclotron that are translatable to other institutions.