Radium needles for medical use. Radium was at the origin of the first uses of radioactive sources for therapeutic purposes. The radium needles, which were rigid, are nowadays replaced by flexible wires containing iridium-192. Radioactive sources are used in the form of tubes or wires introduced in natural cavities or implanted in tissues. Brachytherapy remains today the preferred treatment for uterus cancer, a common and serious cancer.