Author of

• 12544

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  P3.08 - Poster Session 3 - Radiotherapy (ID 199)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Radiation Oncology + Radiotherapy
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/30/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 12568

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    P3.08-024 - Preliminary experience in bronchoscopic placement and in-treatment imaging of two different fiducial markers for guidance of lung cancer radiation. (ID 2758)

    09:30 - 09:30  |  Author(s): C. Fox
    • Abstract

    Background
    During conventional radiation therapy, treatment image guidance is largely indirect relying on slow acquisition 3D volumetric imaging or the use of bony surrogates. Fiducial marker placement within/adjacent to lung tumours facilitates image guided radiation therapy by …….. Marker placement has been attempted percutaneously but is associated with pneumothorax in up to 45%, with frequent use of chest drain tubes. Furthermore, in-treatment imaging protocols are not standardized, and the impact of marker characteristics on accuracy of in-treatment imaging has not previously been reported. We describe our preliminary experience in bronchoscopic implantation and in-treatment tracking/imaging of two different types of lung fiducial marker.

    Methods
    Study design: Prospective observational case series of NSCLC patients undergoing radical radiation treatment . Bronchoscopic implantation: performed under conscious sedation using radial probe endobronchial ultrasound and fluoroscopic guidance to achieve tumour localization and placement within/adjacent to peripheral tumours. Post-implantation/ in-treatment imaging: Time-resolved 4D CT (Philips Brilliance+bellows system) for treatment planning and after completion of treatment to investigate marker movement. Throughout treatment delivery MV electronic portal images (EPI) were acquired plus kV planar and Cone Beam CT (CBCT) (Varian Medical System) images.

    Results
    Four patients with T1N0 NSCLC underwent bronchoscopic implantation of fiducial markers (two using Visicoil[TM] linear fiducial 10x0.75mm, two using SuperDimension® superLock™ 2-band 13x0.9mm markers. Confirmation of tumour localization was achieved with EBUS in all four patients. Two markers were placed in adjacent airways in one patient, and the remainder had a single marker placed within/adjacent to their peripheral tumour. No complications related to bronchoscopy or marker implantation were observed. No marker migration was observed over the treatment time for both marker types. Visibility of the markers in EPI was only possibly in selected beam directions though they were easily discernible in kV planar images (Figure 1a). While diagnostic CT scanning was able to demonstrate the markers in great clarity (Figure 1b), they caused significant image artefacts in CBCT. Figure 1 Figure 1: Image-guided radiotherapy images demonstrating: a) 4DCT image showing visicoil fiducial on maximum intensity projection images, tumour+motion contoured in red, & b) kV orthogonal image showing superLock™ 2-band marker.

    Conclusion
    Our preliminary experience indicates bronchoscopic implantation of fiducial markers is safe, and is achievable with a high degree of accuracy on initial imaging, and stability on subsequent in-treatment imaging. There is a fine balance of marker size minimising CBCT artefacts while allowing visualisation in EPI imaging which would be an ideal tool to verify gated radiotherapy delivery.