A brachytherapy device (20, 21) including a base (22) adapted for being at least partially introduced into a body of a subject and a plurality of radionuclide atoms of a first alpha-emitting isotope, coupled to the base in a manner that not more than 15% of the radionuclide atoms leave the base in 24 hours, in methods other than radioactive decay. When installed in a human subject, the brachytherapy device emits radionuclide atoms of the first alpha-emitting isotope at a rate of at least 0.1% of the number of radionuclide atoms of the first alpha-emitting isotope coupled to the base, per 24 hours.
