Radioactive hydrogels for the delivery of localized radiotherapy, methods of making the radioactive hydrogels, and methods of using the radioactive hydrogels are disclosed. A radioisotope may be conjugated to a high molecular weight molecule, which may be encapsulated in a microparticle, where the microparticle is then dispersed within a hydrogel. The radioactive hydrogel may prevent leakage of the radioisotope to provide radiotherapy to a surgical margin while minimizing damage to surrounding normal tissue.
