Timed-bioresorbable particulates, particularly microspheres or fibers, may be used as a vehicle for delivery of radioisotopes, such as Y-90 and Pd-103 for localized radiotherapy, or as an embolic device. These particulates may also be embedded in polymers, or dispersed in injectable gels or other injectable media for the treatment of various cancers. The benefit of bioresorption, the ability to control the ratio of radioisotopes in the particulate, especially the gamma and beta ratios such as In-111/Y-90 ratio in a particulate, and the benefit of non-conductive implants are disclosed.