Development of 99Mo/99mTc Generator System for Production of Medical Radionuclide 99mTc using a Neutron-activated 99Mo and Zirconium Based Material (ZBM) as its Adsorbent

Abstract

Molybdenum produced from fission of U-235 is the most desirable precursor for ⁹⁹Mo/^99mTc generator system as it is non-carrier added and has high specific activity. However, in the last decade there has been short supply of ⁹⁹Mo due to several constrains. Therefore, there have been many works performed for development of ⁹⁹Mo/^99mTc generator system using ⁹⁹Mo which is not produced from either LEU or HEU. This report deals with development of ⁹⁹Mo/^99mTc generator system where zirconium-based material (ZBM) is used as adsorbent of neutron-activated ⁹⁹Mo. The system was prepared by firstly irradiating natural Mo in the G. A. Siwabessy reactor to produce neutron-activated ⁹⁹Mo. The target was dissolved in NaOH 4N and then neutralized with 12 M HCl. The 99Mo solution was then mixed with a certain amount of ZBM followed by heating at 90°C for three hours to allow the 99Mo adsorbed on ZBM. The 99Mo-ZBM (9.36 GBq of ⁹⁹Mo was Mo/ 4.2 g ZBM) was packed on a fritz-glass column. This column was then fitted serially with an alumina column for trapping ⁹⁹Mo breakthrough. The columns were then eluted daily with saline solution for up to one week. The yield of ^99mTc was found to be between 53.7 – 74% (n= 5). All ^99mTc eluates were clear solutions with pH of 5. Breakthrough of ⁹⁹Mo in ^99mTc eluates was found to be 0.031 ± 0.019 μCi ⁹⁹Mo/ mCi ^99mTc (n= 5) which was less than the maximum activity of ⁹⁹Mo allowed in ^99mTc solution (< 1 µCi ⁹⁹Mo/mCi ^99mTc). Aluminum breakthrough in ^99mTc eluates was found to be less than 10 ppm. The radiochemical purity of ^99mTc in form of Na^99mTcO₄ was > 99%. Radiolabeling of this ^99mTc towards methylene diphosphonate (MDP) kit gave a radiolabelling efficiency of 99%. In summary, a new ⁹⁹Mo/^99mTc generator system that used neutron-activated ⁹⁹Mo and ZBM as its adsorbent has been successfully prepared. The ^99mTc produced from this new ⁹⁹Mo/^99mTc generator system attained the quality of ^99mTc required for medical purposes.

Received: 23 Februari 2016; Revised: 13 July 2016; Accepted: 17 July 2016