thorium-228

Thorium-228 is a radioactive isotope of thorium with a half-life of approximately 1.91 years, belonging to the thorium decay series. In the field of nuclear medicine and oncology, it serves as a critical parent isotope in generator systems used to produce alpha-emitting daughter isotopes, most notably Radium-224 and Lead-212. These daughter isotopes are subsequently chelated to targeting moieties, such as monoclonal antibodies or peptides, to create Targeted Alpha Therapies (TAT). The therapeutic mechanism of action relies on the emission of high-energy alpha particles, which possess high linear energy transfer (LET) and a very short path length in human tissue (typically 50-100 μm). This localized radiation induces dense ionization and lethal, complex double-strand DNA breaks within the targeted tumor cells, effectively bypassing common resistance mechanisms to conventional radiotherapy or chemotherapy while minimizing damage to adjacent healthy tissues. Thorium-228 is a cornerstone of the emerging supply chain for Lead-212-based radiopharmaceuticals, which are currently being investigated for the treatment of various solid tumors and hematologic malignancies.

Other names

Radiothorium