Effect of stoichiometric and preparation parameters on W-188/Re-188 gel generator performance

Rhenium-188 is attractive for pre-targeted rdioimmunotherapy because of its 17 hour half life, energetic beta emission, and availability from a generator. Gel-type W-188/Re-188 radioisotope generators utilize low specific activity W-188 (half-life 69.4 d) to produce compact isotope sources with conventional characteristics, thus expanding the number of reactors able to supply W-188 for radiotherapy. A simple 'one pot' peroxide process has been described previously for this system [1]. Now the effects of gel stoichiometry, boiling rate, and gel digestion on generator parameters of yield, breakthrough, and elution rate have been determined. Optimum conditions give Re-188 yields of 60-80% and W-188 breakthrough values of ∝1 x 10-4%/ml after the generator has been eluted 5-10 times. This Re-188 yield is comparable to that of Tc-99m from a Mo-99/Tc-99m generator made by this process. The most important factor for minimizing breakthrough is gel stoichiometry, which is easily controlled in the peroxide process, while boiling rate mainly affects yields and ease of column elution. (orig.)