C4 is a unique encapsulated positive-signal MRI agent. The Sirius™ MRI Marker is used to facilitate seed localization during LDR brachytherapy. The Orion™ HDR MRI Marker is a unique, positive-signal HDR planning marker. A non-metallic multimodal (MRI, CT and x-ray) fiducial marker for radiotherapy and proton treatment planning is under development.