In modern medicine, radiodense substances are those that will not allow X-rays or similar radiation to pass.
Radiopacity is one of the key considerations in the design of various devices such as guidewires or stents that are used during radiological intervention.
The two main factors contributing to a material's radiopacity are density and atomic number.
Polymer-based devices, however, usually incorporate materials with high electron density contrast compared to the surrounding tissue.
Some solutions involve direct binding of heavy elements, for instance iodine, to polymeric chains in order to obtain a more homogeneous material which has lower interface criticalities.