Radiacode — Pocket-Sized Next-Generation Geiger Counter and Gamma Spectrometer

Radium-224 (Ra-224) is a naturally occurring radioactive isotope of radium with a half-life of about 3.6 days. It decays by alpha emission to radon-220 and is part of the natural thorium-232 decay series. Ra-224 also emits a characteristic gamma ray at approximately 241 keV, although with relatively low intensity.

Ra-224 is of particular interest in targeted alpha therapy because its decay chain releases several high-energy alpha particles over a relatively short period. It is being investigated and used in approaches designed to deliver intense, highly localized radiation to cancer cells while limiting exposure of surrounding tissue. Ra-224 is also used in nuclear medicine and radiopharmaceutical research.

Ra-224 occurs naturally as a member of the thorium-232 decay series, where it is produced by the alpha decay of thorium-228. It can therefore be found in trace amounts in thorium-containing rocks, minerals, soils, and other materials containing natural thorium. Because of its short half-life, Ra-224 is normally present only where it is continuously replenished by its longer-lived parent isotopes.