The isotope 223Ra (under the trade name Xofigo) was approved by the United States Food and Drug Administration in 2013 for use in medicine as a cancer treatment of bone metastasis. The main indication of treatment with Xofigo is the therapy of bony metastases from castration-resistant prostate cancer due to the favourable characteristics of this alpha-emitter radiopharmaceutical. 225Ra has also been used in experiments concerning therapeutic irradiation, as it is the only reasonably long-lived radium isotope which does not have radon as one of its daughters.