Actinium is 150 times more radioactive than radium which makes it a valuable neutron source for radio-immunotherapy and Targeted Alpha Therapy. Trace amounts of actinium are found in uranium ores. For every ton of uranium ore, there is about one-tenth of a gram of actinium. Actinium is also produced by irradiating radium-226 with neutrons in a nuclear reactor. The homologue of actinium is lanthanum.