224Ra

Radium-224 (228Ra is different; this entry concerns 224Ra) is a radioactive isotope of the element radium, with a mass number of 224 and atomic number 88. It is a member of the thorium-232 decay series and has a relatively short half-life compared with many other radionuclides.

The primary mode of decay for 224Ra is alpha emission, which transforms it into radon-220 (thoron). The decay chain continues through a series of short-lived daughters, including polonium-216 and lead-212, before reaching stable lead-208. The chain involves both alpha and beta decays, with rapid progress through the intermediate radionuclides.

Natural occurrence and production commonly arise in trace amounts from thorium-bearing materials as part of natural decay processes. Artificial production can occur in nuclear facilities by neutron irradiation of thorium targets or through pathways involving other radium isotopes, enabling isolation of 224Ra for research or experimental use.

Chemically, radium behaves like other group 2 elements and is highly reactive with water and air, though in radiological contexts it is handled in controlled environments. In medical contexts, radium isotopes tend to localize in bone due to chemical similarity to calcium, which has informed the development of bone-targeted radiopharmaceutical approaches for alpha therapy; however, 224Ra has not been as widely used clinically as some other radium isotopes such as 223Ra.

Applications and research for 224Ra have centered on its potential for targeted alpha therapy, dosimetry challenges, and radiopharmacology, but clinical adoption remains limited. Handling requires strict radiological controls because alpha emitters and their short-lived daughters can deliver high localized doses if not properly contained.

See also: radium isotopes, radon-220, targeted alpha therapy, lead-208.