Ga67

Gallium-67 (Ga-67) is a radioactive isotope of gallium with a mass number of 67. It decays by electron capture to stable zinc-67 and emits gamma rays that can be detected by gamma cameras, enabling single-photon emission imaging. Its half-life is about 3.26 days, which allows imaging over several days but also contributes to a significant radiopharmaceutical dose.

Production and availability

Ga-67 is produced in nuclear reactors or cyclotrons through various target reactions and is then separated and purified for medical use. Production methods and radiochemical purification are designed to maximize radionuclidic purity and minimize contaminants. Ga-67 is typically supplied as a radiopharmaceutical complex, such as gallium-67 citrate, for clinical imaging.

Clinical use

The primary radiopharmaceutical form is gallium-67 citrate, used in Ga-67 scans to detect inflammatory and infectious processes and to aid in oncology, particularly in suspected lymphoma and certain metastatic or inflammatory conditions. Ga-67 imaging has historically played a role in evaluating fever of unknown origin, occult infections, and inflammatory diseases like sarcoidosis. Because Ga-67 localizes to areas of increased vascular permeability and to inflammatory cells, it can highlight sites of disease that may not be evident on other imaging modalities.

Imaging characteristics and limitations

Ga-67 emits gamma radiation at multiple energies, enabling planar and SPECT imaging. Uptake is often evaluated at 24 to 72 hours after administration, reflecting complex biodistribution and retention in lesions. Compared with modern PET/CT tracers, Ga-67 imaging generally offers lower resolution and specificity, and its use has declined in many settings.

Safety and regulation

As with all radiopharmaceuticals, Ga-67 imaging requires appropriate radiological protection, dosimetry planning, and institutional approvals. It remains a niche tool in nuclear medicine, used where suitable indications exist and where other modalities are not available or applicable.