Disclosed herein are fiducial markers that include a sealed casing member containing a mixture of iodine and water that includes about 1-300 mg/ml iodine. The fiducial markers may be distinguishable on at least two imaging modalities, such as CT and MRI. The casing member may include a plastic or elastomeric material, such as polyvinyl chloride (PVC) polypropylene, latex, nylon, dynaflex, and may take the form of a length of IV tubing sealed at each of two ends. The length of IV tubing may be crimped to form a desired shape, such as a triangle. Also disclosed are methods of making fiducial markers that are distinguishable on at least two imaging modalities, such as CT and MRI.
