Reproducibility of "Intelligent" Contouring of Gross Tumor Volume in Non-Small-Cell Lung Cancer on PET/CT Images Using a Standardized Visual Method

Michael Bayne, Rodney J. Hicks, Sarah Everitt, Natalie Fimmell, David Ball, John Reynolds, Eddie Lau, Alex Pitman, Robert Ware, Michael MacManus

Research output: Contribution to journalArticleResearchpeer-review

52 Citations (Scopus)

Abstract

Purpose: Positron emission tomography/computed tomography (PET/CT) is increasingly used for delineating gross tumor volume (GTV) in non-small-cell lung cancer (NSCLC). The methodology for contouring tumor margins remains controversial. We developed a rigorous visual protocol for contouring GTV that uses all available clinical information and studied its reproducibility in patients from a prospective PET/CT planning trial. Methods and Materials: Planning PET/CT scans from 6 consecutive patients were selected. Six "observers" (two radiation oncologists, two nuclear medicine physicians, and two radiologists) contoured GTVs for each patient using a predefined protocol and subsequently recontoured 2 patients. For the estimated GTVs and axial distances, least-squares means for each observer and for each case were calculated and compared, using the F test and pairwise t-tests. In five cases, tumor margins were also autocontoured using standardized uptake value (SUV) cutoffs of 2.5 and 3.5 and 40% SUVmax. Results: The magnitude of variation between observers was small relative to the mean (coefficient of variation [CV] = 3%), and the total variation (intraclass correlation coefficient [ICC] = 3%). For estimation of superior/inferior (SI), left/right (LR), and anterior/posterior (AP) borders of the GTV, differences between observers were also small (AP, CV = 2%, ICC = 0.4%; LR, CV = 6%, ICC = 2%; SI, CV 4%, ICC = 2%). GTVs autocontoured generated using SUV 2.5, 3.5, and 40% SUVmax differed widely in each case. An SUV contour of 2.5 was most closely correlated with the mean GTV defined by the human observers. Conclusions: Observer variation contributed little to total variation in the GTV and axial distances. A visual contouring protocol gave reproducible results for contouring GTV in NSCLC.

Original languageEnglish
Pages (from-to)1151-1157
Number of pages7
JournalInternational Journal of Radiation Oncology Biology Physics
Volume77
Issue number4
DOIs
Publication statusPublished - 15 Jul 2010
Externally publishedYes

Keywords

  • Computed tomography
  • Non-small-cell lung cancer
  • Positron emission tomography
  • Radiation therapy

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