Composition in the form of a shaped device, for use as a fiducial marker in tissues in the animal body, in radiotherapy and/or radiosurgery, characterized in that it comprises:a core consisting of a colloidal dispersion of metal nanoparticles and/or oxides or metal salts having X-ray-contrast properties, where said nanoparticles are stabilized with surfactants, polymers or capping agents in a liquid vehicle, anda polymeric casing that encapsulates the core, said device having a minimum size of not less than 500 microns and a maximum size not greater than 3000 microns.

Composition in the form of a shaped device, for use as a fiducial marker in tissues in the animal body, in radiotherapy and/or radiosurgery, characterized in that it comprises: a core consisting of a colloidal dispersion of metal nanoparticles and/or oxides or metal salts having X-ray-contrast properties, where said nanoparticles are stabilized with surfactants, polymers or capping agents in a liquid vehicle, and a polymeric casing that encapsulates the core, said device having a minimum size of not less than 500 microns and a maximum size not greater than 3000 microns.

The present invention relates to hydrogels comprising 1,2-diol or 1,3-diol groups acetalized with a radiopaque species of one or more covalently bound radiopaque halogens which are imageable during embolization therapy. The invention further relates to methods of making radiopaque polymers and radiopaque hydrogel microspheres to provide an imageable drug delivery system.

In some aspects, the present disclosure pertains to radiopaque crosslinked acrylamide copolymers that comprise (a) a residue of an iodinated monofunctional unsaturated monomer that comprises (i) a single acrylamido group or a single methacrylate group and (ii) one or more iodinated aromatic groups linked to the acrylamido group or the methacrylate group through a linkage comprising a C.sub.2-C.sub.8 alkyl group, (b) a residue of a monofunctional acrylamide monomer that does not contain an iodinated aromatic group, and (c) a residue of a multifunctional acrylamide monomer that does not contain an iodinated aromatic group. Other aspects of the present disclosure pertain to methods of making such radiopaque crosslinked acrylamide copolymers, to particulate compositions containing such radiopaque crosslinked acrylamide copolymers, and to methods of treatment using such particulate compositions.