Provided is a process of producing activated particles comprising 188Re-isotopes and/or 186Re-isotopes by irradiating non-volatile and water-insoluble starting particles comprising a rhenium compound with neutrons. Further provided is a process of producing corresponding non-volatile and water-insoluble starting particles. Further provided are respective starting particles and activated particles, respectively, and a composition comprising a plurality of activated particles. The activated particles, and the composition comprising same are suitable for use in radionuclide therapy, and for cosmetic applications.
