Quantification of Mediastinal and Hilar Lymph Node Movement Using Four-Dimensional Computed Tomography Scan: Implications for Radiation Treatment Planning

David J. Sher, John A. Wolfgang, Andrzej Niemierko, Noah C. Choi

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

Abstract

Purpose: To quantitatively describe mediastinal and hilar lymph node movement in patients with lymph node-positive lung cancer. Methods and Materials: Twenty-four patients with lung cancer who underwent four-dimensional computed tomography scanning at Massachusetts General Hospital were included in the study. The maximum extent of superior motion of the superior border was measured, as well as the maximum inferior movement of the inferior border. The average of these two values is defined as the peak-to-peak movement. This process was repeated for mediolateral (ML) and anterior-posterior (AP) movement. Linear regression was used to determine lymph node characteristics associated with peak-to-peak movement. Various uniform expansions were investigated to determine the expansion margins necessary to ensure complete internal target volume (ITV) coverage. Results: The mean peak-to-peak displacements of paratracheal lymph nodes were 4 mm (craniocaudal [CC]), 2 mm (ML), and 2 mm (AP). For subcarinal lymph nodes, the mean peak-to-peak movements were 6 mm (CC), 4 mm (ML), and 2 mm (AP). The mean peak-to-peak displacements of hilar lymph nodes were 7 mm (CC), 1 mm (ML), and 4 mm (AP). On multivariate analysis, lymph node station and lymph node size were significantly related to peak-to-peak movement. Expansions of 8 mm for paratracheal nodes and 13 mm for subcarinal and hilar nodes would have been necessary to cover the ITV of 95% of these nodal masses. Conclusions: Subcarinal and hilar lymph nodes may move substantially throughout the respiratory cycle. In the absence of patient-specific information on nodal motion, expansions of at least 8 mm, 13 mm, and 13 mm should be considered to cover the ITV of paratracheal, subcarinal, and hilar lymph nodes, respectively.

Original languageEnglish (US)
Pages (from-to)1402-1408
Number of pages7
JournalInternational Journal of Radiation Oncology Biology Physics
Volume69
Issue number5
DOIs
StatePublished - Dec 1 2007

Keywords

  • Computed tomography
  • Four-dimensional treatment planning
  • Lung cancer
  • Organ motion
  • Treatment planning

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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