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

86Y is an attractive PET radionuclide due to its intermediate half-life. (86)Y was produced via the 86Sr(p,n)86Y nuclear reaction. Enriched SrCO3 or SrO was irradiated with 2-6 microA of beam current for <4 h on a CS-15 cyclotron. It was shown that the SrO target could withstand at least 6 microA of beam current, a significant improvement over a maximum of 2 microA on the SrCO3 target. Average yields of 4.5 mCi/microA.h were achieved with SrO, which represent 71% of the theoretical yield, compared to 2.3 mCi/microA.h with SrCO3. The radioisotopic contaminants were (86m)Y (220%), 87Y (0.27%), (87m)Y (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 (86)Y was collected from the Pt wire using 2.8 M HNO3/EtOH (3:1). After evaporation, 86Y was reconstituted in 100 microl of 0.1 M HCl. Target materials were recovered as SrCO3 and then converted to SrO by thermal decomposition at 1150 degrees C. Specific activity of 86Y was determined to be 29+/-19 mCi/microg 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.