Ga68

Gallium-68 (Ga-68) is a positron-emitting radionuclide used primarily in diagnostic positron emission tomography (PET) imaging. It has a relatively short half-life of about 68 minutes and decays to stable zinc-68, predominantly by positron emission. The combination of a short half-life and PET suitability enables high-contrast images with limited radiation exposure to patients.

Production and availability

Ga-68 is typically obtained from a germanium-68/gallium-68 generator. The parent isotope, germanium-68, has a half-life of about 271 days, allowing the generator to supply Ga-68 over many weeks to months. Ga-68 is eluted from the generator and then rapidly formulated into radiopharmaceuticals in a radiopharmacy. The short half-life necessitates on-site or nearby production and timely scheduling of imaging procedures.

Chemistry and radiopharmaceuticals

Chemically, gallium behaves as Ga3+ and forms stable complexes with chelators such as DOTA. This enables labeling of peptides or small molecules that target specific biological receptors. Widely used Ga-68 radiopharmaceuticals include Ga-68 DOTATATE, Ga-68 DOTATOC, and Ga-68 DOTANOC for imaging somatostatin receptor–positive neuroendocrine tumors, and Ga-68 PSMA-11 for imaging prostate cancer. Additional Ga-68–labeled tracers targeting other receptors and processes are under development.

Medical applications

Ga-68–labeled radiopharmaceuticals are employed in PET imaging to stage disease, detect recurrence, and monitor therapy. The most established uses are imaging neuroendocrine tumors via somatostatin receptor expression and prostate cancer via PSMA expression, with quantitative uptake measures aiding clinical decision-making.

Safety and limitations

As with other radiopharmaceuticals, Ga-68 tracers involve radiation exposure, balanced by the short half-life and targeted uptake. Availability depends on generator supply, and production requires specialized facilities and regulatory compliance.