Development of a SnO2-based 44Ti/44Sc generator for medical applications

Abstract

Towards application of 44Sc for diagnostic nuclear medicine, a 44Ti/44Sc generator based on an inorganic resin has been evaluated. Unlike other radionuclide generators used for medical applications, the long-term retention of the parent 44Ti is vital due to its long half life. Herein, tin dioxide (SnO2), a robust inorganic-based resin, has been synthesized and used as the stationary phase for a 44Ti/44Sc generator. The sorption behavior of 44Ti/44Sc was tested on SnO2 with varying acids, concentrations, and times. Preliminary batch study results showed >88 % 44Ti retention to the resin at lower acid concentrations (0.05 M HNO3 and 0.05 M HCl). A pilot generator was evaluated for a year, demonstrating 85.3 ± 2.8 % 44Sc elution yields and 0.71 ± 0.14 % 44Ti breakthrough in 5 M HNO3. Based on capacity studies, a 7.4 MBq (200 µCi) upscaled generator system was constructed for further evaluation of the SnO2 resin stability and the efficacy of the eluted 44Sc for radiolabeling. 44Sc could be regularly eluted from this generator in 5 M HNO3 with an overall average radiochemical yield 84.7 ± 9.5 %. Post-elution processing of the 44Sc with DGA-normal resin removed all 44Ti present and allowed for high 44Sc-DOTA labeling yields of 94.2 ± 0.5 %. Overall, SnO2 has been shown to be a viable material for a 44Ti/44Sc generator.