A device intended to be implanted within the body, either temporarily or permanently, to create identifying marks that can be seen on radiological images. It is typically in the form of a wire, needle, bead, clip, stent-like tube, washer or fluid, and used to locate and delineate a tumour, lesion, or other site of interest. It is made from materials compatible with the imaging system with which it is intended to be used [e.g., magnetic resonance imaging (MRI), x-ray, or nuclear medicine]; it may be intended for use during radiotherapy procedures. It is not an electromagnetic or optical spatial marker.