Researchers at the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS) have conducted a study on the separation route of germanium-68 and successfully prepared a germanium-68/gallium-68 generator.

Published in Applied Radiation and Isotopes, the study lays a good foundation for producing the generator-based medical isotope gallium-68 in China.

Positron emission computed tomography (PET) is an advanced imaging technique used in the clinical field of nuclear medicine. The medical isotope fluorine-18 is widely used in PET for detection of cancer. Usually, fluorine-18 is produced by an onsite cyclotron in hospitals.

As the application of gallium-68 in nuclear medicine is growing quickly on a global scale, obtaining gallium-68 directly from the germanium-68/gallium-68 generator has received much attention. More importantly, the generator could be used for a long time because of the long half-life period (about 271 days) of the mother nuclide germanium-68.

The quantity and purity of germanium-68 is of great importance in producing gallium-68. In this study, the researchers from IMP reported an efficient method to produce and separate germanium-68. They prepared the Ga-Ni alloy target with large area by electroplating. And the content of gallium-68 in the Ga-Ni layer could attain 78% by weight. The Ga-Ni target was bombarded using a proton beam for 10 hours. After "cooling" for a long period, they applied an automated system equipped with double-column chromatography to separate germanium-68 with recovery of about 70%.

Then, the researchers used separated germanium-68 to assemble the SnO₂ germanium-68/gallium-68 generator. They collected gallium-68 in about 70% yields with high radioactive concentration. The eluted gallium-68 has a radionuclidic purity of > 99.9% and a radiochemical purity of > 99%, which satisfies the requirement of European Pharmacopeia.

The techniques presented in this study are expected to be applied in production of germanium-68/gallium-68 generators, facilitating the development of gallium-68 radiopharmaceuticals in China.