title: Multimodality guidance for accurate bronchoscopic insertion of fiducial markers.
abstract: BACKGROUND
  Fiducial markers act as visible surrogates of tumor position during image-guided radiotherapy. Marker placement has been attempted percutaneously but is associated with high rates of pneumothorax and chest drain placement.
  
  
  METHODS
  Patients undergoing radical radiation treatment for non-small-cell lung cancer underwent bronchoscopic implantation of gold fiducials using radial probe endobronchial ultrasound (EBUS) with virtual bronchoscopy and fluoroscopic guidance to achieve tumor localization and placement within/adjacent to peripheral lung tumors. For tumors not localized using radial EBUS, fiducial placement was achieved by electromagnetic navigation to the vicinity of the tumor.
  
  
  RESULTS
  Eighteen fiducials were placed to mark 16 lesions in 15 patients. In nine patients (60%), fiducials were implanted at the time of diagnostic bronchoscopy. No procedural complications occurred. EBUS localization allowed marker implantation within the target lesion in 12 cases. In four lesions, electromagnetic navigation bronchoscopy-guided implantation achieved a median fiducial-lesion distance of 6 mm (mean 12 mm). No marker migration occurred after the implantation of two-band markers; however, early migration was observed in two of eight (25%) of the smaller linear fiducials. No migration during the course of radiation therapy was observed.
  
  
  CONCLUSIONS
  Fiducial marker placement is easily and safely performed bronchoscopically, including at the time of diagnostic bronchoscopy. Marker geometry appears important in stability of bronchoscopically inserted fiducials. Future studies are required to confirm the optimal marker size, geometry, and spatial relationship with the target lesion.
authors.affiliation: *Department of Medicine, University of Melbourne, Parkville, Australia; †Department of Respiratory Medicine, Royal Melbourne Hospital, Parkville, Australia; ‡Department Cancer Medicine, Peter MacCallum Cancer Institute, East Melbourne, Australia; §Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Institute, East Melbourne, Australia; ║Department of Physical Sciences, Peter MacCallum Cancer Institute, East Melbourne, Australia; ¶Radiation Oncology, Genesis Cancer Care WA, Perth, Australia; #School of Surgery, University of Western Australia, Perth, Australia; **William Buckland Radiotherapy Centre, Prahran, Australia; and ††Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Australia.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Steinfort
authors.forename: Shankar
authors.initials: S
authors.lastname: Siva
authors.forename: Tomas
authors.initials: T
authors.lastname: Kron
authors.forename: Raphael R
authors.initials: RR
authors.lastname: Chee
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Ruben
authors.forename: David L
authors.initials: DL
authors.lastname: Ball
authors.forename: Louis B
authors.initials: LB
authors.lastname: Irving
mesh_terms: D001999:Bronchoscopy / Q000295:instrumentation / Q000379:methods*; D057918:Fiducial Markers; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000532:radiotherapy; D064847:Multimodal Imaging / Q000295:instrumentation* / Q000379:methods; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D013238:Stereotaxic Techniques / Q000295:instrumentation*