Europium-152 as a potential substitute for cobalt-60 in radiation therapy.

Construction has begun of prototype europium-152 sources, with the principal goal of providing cost-effective teletherapy for emergent nations where prices for cobalt-60 are excessive, owing to replacement needs, and the use of linacs is economically prohibitive and technologically unfeasible. 152Eu sources (T1/2 = 13.4y vs T1/2 = 5.26y for 60Co) are designed for absorbed dose rates > 1.5 Gy/min at 1 m, with specific activities > 5 TBq/gm, allowing substitution into existing irradiators. Costs of 152Eu compare favorably with 60Co, taking account of extended useful lifetime.