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Yttrium is a silvery transition metal, discovered in mineral form in 1794 in the Swedish village of Ytterby. Yttrium-90 is a synthetic radioisotope produced for therapy, with a half-life of about 2.7 days.
Yttrium-90 is a pure beta emitter, decaying to stable zirconium-90 by releasing high-energy beta particles. These deposit their dose over a short range of only a few millimetres in tissue, concentrating radiation on the target while sparing surrounding healthy cells.
Yttrium-90 is best known for radioembolization, or selective internal radiation therapy (SIRT), in which tiny microspheres carrying the isotope are injected into the arteries feeding liver tumours, lodging in the tumour's blood supply to irradiate it from within. It plays a significant role in treating hepatocellular carcinoma and liver metastases and has also been used in radioimmunotherapy for lymphoma and in treating inflamed joints.
Yttrium-90 is produced either by eluting it from a strontium-90/yttrium-90 generator, where the long-lived fission product strontium-90 decays to yttrium-90, or by direct neutron activation of yttrium-89 in a reactor. Both routes therefore depend on reactor-derived material and neutron capacity.
StandardX is developing accelerator-driven production to strengthen reliable, high-purity supply of yttrium-90.