Interfractional positional variability of fiducial markers and primary tumors in locally advanced non-small-cell lung cancer during audiovisual biofeedback radiotherapy

Nicholas O. Roman, Wes Shepherd, Nitai Mukhopadhyay, Geoffrey D. Hugo, Elisabeth Weiss

Research output: Contribution to journalArticlepeer-review

40 Scopus citations

Abstract

Purpose: To evaluate implanted markers as a surrogate for tumor-based setup during image-guided lung cancer radiotherapy with audiovisual biofeedback. Methods and Materials: Seven patients with locally advanced non-small-cell lung cancer were implanted bronchoscopically with gold coils. Markers, tumor, and a reference bony structure (vertebra) were contoured for all 10 phases of the four-dimensional respiration-correlated fan-beam computed tomography and weekly four-dimensional cone-beam computed tomography. Results: The systematic/random interfractional marker-to-tumor centroid displacements were 2/3, 2/2, and 3/3 mm in the x (lateral), y (anterior-posterior), and z (superior-inferior) directions, respectively. The systematic/random interfractional marker-to-bone displacements were 2/3, 2/3, and 2/3 mm in the x, y, and z directions, respectively. The systematic/random tumor-to-bone displacements were 2/3, 2/4, and 4/4 mm in the x, y, and z directions, respectively. All displacements changed significantly over time (p < 0.0001). Conclusions: Although marker-based image guidance may decrease the risk for geometric miss compared with bony anatomy-based positioning, the observed displacements between markers and tumor centroids indicate the need for repeated soft tissue imaging, particularly in situations with large tumor volume change and large initial marker-to-tumor centroid distance.

Original languageEnglish
Pages (from-to)1566-1572
Number of pages7
JournalInternational Journal of Radiation Oncology Biology Physics
Volume83
Issue number5
DOIs
StatePublished - Aug 1 2012

Keywords

  • Fiducial marker
  • Four-dimensional cone-beam computed tomography
  • Interfractional displacement
  • Lung cancer

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