Brachytherapy in Equine Practice

Brachytherapy involves the insertion of sealed radioactive sources directly into a tumour to kill neoplastic cells. Ionising radiation is emitted from the radioactive sources to allow the administration of high doses of radiation to a targeted area, with minimal exposure to the surrounding tissues.

Brachytherapy is used in human medicine for the treatment of certain types of cancer including prostate, cervical, uterine and breast cancer among others. Manual loading brachytherapy (as is currently used in equine medicine) is becoming increasingly rare in human medicine due to health and safety concerns. Fully automated high dose-rate afterloading brachytherapy or permanent seed brachytherapy are more commonly used in conjunction with advanced imaging techniques. These techniques may become more available in equine practice in the future.

In equine medicine, brachytherapy using iridium-192 (Ir192) is most commonly used. Ir192 is produced by neutron activation from iridium-191 with the release of gamma radiation. The half-life is approximately 74 days. The iridium is used in the form of wires or small seeds fixed into ribbons. The seeds or ribbon have a central radioactive core and are surrounded by a thin platinum sheath. [...]