Long term safety and visibility of a novel liquid fiducial marker for use in image guided radiotherapy of non-small cell lung cancer.

•Report on safety and clinical feasibility of a novel liquid fiducial marker for radiotherapy in lung cancer patients.•No serious safety or toxicity issues related to implantation procedure, radiotherapy or follow-up period.•Visible in ultrasound, kV X-ray, CT and ConeBeam CT images.•Slow degradation and no migration of the marker in follow up CT images.•Clinically feasible for use as a fiducial marker in radiotherapy of lung cancer patients.