Abstract: Microparticles comprising a core, at least one linking carrier on the core, and at least one radioactive therapeutic agent covalently bonded to the linking carrier. The radioactive therapeutic agent may be a radionuclide or a radiopharmaceutical. A method of radiation therapy of a patient by administering to the patient the microparticles. The treatment may be radiation therapy to treat cancer or a tumor. A kit for preparing a microparticle treatment and a method for using the kit to prepare a microparticle treatment dose. The microparticle treatment dose may be made at a location of administration or at a site proximate to the location of administration, such as a local radiopharmacy, laboratory, hospital or physician's office.