Initial experience in preparation and evaluation of alumina column based ¹⁸⁸W— ¹⁸⁸Re generator system.

¹⁸⁸Re has many attractive properties for variety of radionuclidic therapy (RNT) (t_1/2 16.9 h, E_â max 2.12 MeV and 15% Eã 155 keV suitable for imaging) including cancer therapy, treatment of bone pain due to metastases, intra arterial brachytherapy for inhibition of restenosis following coronary angioplasty in nuclear medicine. ⁸⁸Re has the advantage that it can be obtained from the ¹⁸⁸W (t_1/2 69.4d)-¹⁸⁸Re (t_1/216.9 h) generator system. ¹⁸⁸Re is available by radioactive decay of ¹⁸⁸W and separable by analogous ion-exchange methods to those used for ^99mTc. Similar to normal saline elution of ^99mTc as sodium pertechnetate from ^99mTc generator, elution of ¹⁸⁸W—¹⁸⁸Re generator with normal saline provides a ready source of ‘carrier free’ ¹⁸⁸Re-perrhenate for labeling. Because of the similarity of its coordination chemistry with that of its widely used lighter congener technetium, several ¹⁸⁸Re radiopharmaceuticals have already been developed.

Two alumina column based ¹⁸⁸W— ¹⁸⁸Re generators were prepared using high specific activity ¹⁸⁸W of 216.8GBq/g (5.86Ci/g) obtained from the International Atomic Energy Agency. The ¹⁸⁸W activity was adsorbed on a preconditioned acidic alumina bed (4g, 35x13mm) after acidifying (pH 2–3) with 0.1N HCl solution. The column was washed with 100ml of normal saline. Two such generators of ¹⁸⁸W activities 2.4GBq (65mCi) and 0.6GBq (16mCi), on reference date, were prepared and evaluated for a period of 5 months. Perrhenate was eluted each day with 10ml of normal saline. The mean elution yield of perrhenate from 2.4GBq the generator was 82.5±1.89% (n=10) and 83.3±3.23%(n=16) from 0.6GBq generator. The radiochemical purity of eluted ¹⁸⁸Re perrhenate in 0.9% NaCl by means of paper chromatography [ITLC, saline] was greater than 99%. Radionuclidic purity of the ¹⁸⁸Re eluate was checked ãspectroscopy using HPGe detector coupled with multichannel analyzer.¹⁸⁸W breakthrough was less than 10⁻³% in both the generators. The preparation and evaluation of ¹⁸⁸W—¹⁸⁸Re generator has thus been demonstrated successfully.