Germanium68

Germanium-68 (Ge-68) is a radioactive isotope of the element germanium with mass number 68. It has a half-life of 270.8 days and decays by electron capture to the radioisotope gallium-68 (Ga-68). The Ga-68 produced then decays by positron emission with a half-life of 68 minutes, enabling positron emission tomography (PET) imaging.

Ge-68 is most widely encountered as the parent nuclide in the Ge-68/Ga-68 generator, a compact device that provides Ga-68 on demand for radiopharmaceutical labeling. The generator typically consists of a column containing Ge-68 adsorbed on a resin, from which Ga-68 is eluted with a simple acid solution.

Ga-68 radiopharmaceuticals, such as Ga-68-DOTATATE, Ga-68-DOTATOC, Ga-68-DOTANOC and Ga-68-PSMA-11, are widely used in PET oncology imaging to visualize neuroendocrine tumors and prostate cancer. The short half-life of Ga-68 (68 minutes) makes on-site production practical, while the longer half-life of Ge-68 allows long-term generator use.

Ge-68 is produced in nuclear reactors or accelerators by irradiation of targets such as enriched Ga-69, Ga targets, or Ge targets using proton or neutron beams, followed by chemical purification to separate Ge-68. Production routes include (p,2n) reactions on Ga-69 and various spallation or (n,γ) processes on heavier targets.

Handling Ge-68 and Ga-68 requires adherence to radiation safety guidelines. The long half-life of Ge-68 requires secure, long-term storage and monitoring of generators, while the short-lived Ga-68 demands efficient planning for radiopharmaceutical labeling and timely patient administration.