Background
In this work, a lutetium-177 (
177
Lu) production method based on the separation of nuclear isomers,
177m
Lu &
177
Lu, is reported. The
177m
Lu-
177
Lu separation is performed by combining the use of DOTA & DOTA-labelled peptide (DOTATATE) and liquid-liquid extraction.
Methods
The
177m
Lu cations were complexed with DOTA & DOTATATE and kept at 77 K for periods of time to allow
177
Lu production. The freed
177
Lu ions produced via internal conversion of
177m
Lu were then extracted in dihexyl ether using 0.01 M di-(2-ethylhexyl) phosphoric acid (DEHPA) at room temperature. The liquid-liquid extractions were performed periodically for a period up to 35 days.
Results
A maximum
177
Lu/
177m
Lu activity ratio of 3500 ± 500 was achieved with [
177m
Lu]Lu-DOTA complex, in comparison to
177
Lu/
177m
Lu activity ratios of 1086 ± 40 realized using [
177m
Lu]Lu-DOTATATE complex. The
177
Lu-
177m
Lu separation was found to be affected by the molar ratio of lutetium and DOTA. A
177
Lu/
177m
Lu activity ratio up to 3500 ± 500 was achieved with excess DOTA in comparison to
177
Lu/
177m
Lu activity ratio 1500 ± 600 obtained when lutetium and DOTA were present in molar ratio of 1:1. Further, the
177
Lu ion extraction efficiency, decreases from 95 ± 4% to 58 ± 2% in the presence of excess DOTA.
Conclusion
The reported method resulted in a
177
Lu/
177m
Lu activity ratio up to 3500 after the separation. This ratio is close to the lower end of
177
Lu/
177m
Lu activity ratios, attained currently during the direct route
177
Lu production for clinical applications (i.e. 4000–10,000). This study forms the basis for further extending the liquid-liquid extraction based
177m
Lu-
177
Lu separation in order to lead to a commercial
177m
Lu/
177
Lu radionuclide generator.
Electronic supplementary material
The online version of this article (10.1186/s41181-019-0064-5) contains supplementary material, which is available to authorized users.