Separation of 103Pd from Ag and Rh targets for production of '103 Pd seeds' for prostate cancer brachytherapy

[摘要] ENGLISH ABSTRACT:Radiochemical separation of 103Pd from natAg, usmg a 66 MeV proton-inducedreaction at iThemba LABS, was studied and a radiochemical method was developedfor the separation. For the separation, which comprises the separation of Pd from alarge amount of target material (16 g Ag), as well as Rh radioisotopes produced fromdecay of their Pd parents (mainly 101Rhand IOORh),three ion exchange resins weretested: a Chelex 100 chelating resin, the AG 1-X8 anion exchange resin and aAG MP-I anion exchange resin. For the optimum elution ofPd from the latter tworesins, two elution curves using water and 5% ammonia solution, were obtained.With an average recovery of 97.4% and sharper elution curve from the macroporousAG MP-I, this resin was finally chosen for routine production. To achieve theseparation, a simple, easily operated radiochemical processing system was designedand installed in a hot cell.Radiochemical separation of 103Pd from a Rh target was also studied and severalcation and anion exchange resins were tested. A carrier-free separation of 103Pd wasdeveloped, using an AG 1-X8 anion exchange resin. Bombarded tablets ofRhCh.3H20, as the targets, were used for these separations. The procedure,originally designed for the separation of Pd from Cu and Rh, was modified usingH202 for the oxidation of Ru prior to the sorption on the resin and successfully usedfor the separation of isotopes of Rh from the isotopes of Pd, Ru, Tc, Nb, Mo, Zrand Y, which were produced by 400 MeV 160_ and 12C-induced RhCb.3H20targets. To elute the Pd from the resin, 5% ammonia solution was used; therecovery was about 92%.To prepare the Rh target for routine production, an electroplating method of Rh on aCu substrate was developed. Rh(CI04)3, in 0.5 M perchloric acid, was used as theelectrolyte bath. The electroplated Rh was then dissolved by an alternating currenttechnique, using 6 M HCI and a current density of 2 Alcm2.For production of the seeds, I03Pd was sorbed on the weakly basic anion exchangeresin Amberlite IRA-93 (600-700 Il), by recycling a 0.5 M Hel solution of Pdthrough a 0.5 cm x 1 cm column for 2 hours. The distribution of I03Pd on the resinbeads was measured and RSD of5.7% was obtained.A funnel was designed to transfer the I03Pd-loaded resin beads into the Ti tubes toprepare the seeds (0.7 mm LD., 0.8 mm D.D., and 4.5 mm length). To enclose thetubes as capsules, the end caps were made from 0.02 mm Ti sheet and several pieceswere designed and machined for the welding of the caps to the tubes. A spotweldingmachine was used for the welding, after small, but vital modifications.

[发布机构] Stellenbosch University