A new, portable solvent extraction-based molybdenum-99/technetium-99m generator utilizing (n, γ) molybdenum-99 in sodium chloride solution for hospital radiopharmacy

Technetium-99m (^99mTc, t_1/2= 6.02 h; 140.51 keV (89%)) is the most important and useful radioisotope in diagnostic nuclear medicine. The methyl ethyl ketone (MEK)-based solvent extraction technique is a well-known method for the separation of ^99mTc from low specific activity molybdenum-99 (⁹⁹Mo). Here, we report a new, portable solvent extraction-based ⁹⁹Mo/^99mTc generator in tandem with alumina column utilizing (n,γ) ⁹⁹Mo to produce highly purified, concentrated, clinical grade ^99mTc. The pH of the aqueous solution of (n,γ) ⁹⁹Mo (200-500 mCi) in dilute NaOH was adjusted to 7 and saturated with solid NaCl and then transferred to an extraction tube (50 ml) kept in the lead shielded arrangement. The pertechnetate (^99mTcO₄−) was selectively extracted in MEK and passed through two small alumina column (neutral alumina and acidic alumina). Finally, highly pure ^99mTc was recovered from acidic alumina column with 3-5 ml saline in high concentration. The performance of this new ⁹⁹Mo/^99mTc generator was evaluated by studying the recovery yield of ^99mTc, physicochemical tests, and radiolabeling with Tc cold kits such as methylene diphosphonate (MDP), diethylene-triamine-pentaacetate acid (DTPA) and sestamibi (MIBI). The average yield of separation of ^99mTc was above 90% and ⁹⁹Mo breakthrough in ^99mTc pertechnetate was <0.0002% (n = 10). The final ^99mTcO₄^- fraction has the Mo and Al content <10 ppm and MEK content <0.1% v/v, with radiochemical (RC) purity >99% and radionuclidic (RN) purity >99.9%. The efficacy of labeling specific compounds was assessed using standard radiopharmaceutical kits, such as ^99mTc-MDP, ^99mTc-DTPA, and ^99mTc-MIBI, and RC purity was above 95% (n = 6). The newly developed portable ⁹⁹Mo/^99mTc generator can provide the highly concentrated and purified ^99mTc-pertechnetate using low specific activity ⁹⁹Mo and finds its application for hospital radiopharmacy. (author)