Interobserver delineation variation in lung tumour stereotacticbody radiotherapy

Publication: Research - peer-reviewJournal article – Annual report year: 2012

  • Author: Persson, G. F.

    Copenhagen University Hospital, Denmark

  • Author: Nygaard, D. E.

    Copenhagen University Hospital, Denmark

  • Author: Hollensen, Christian

    Image Analysis and Computer Graphics, Department of Informatics and Mathematical Modeling, Technical University of Denmark, Denmark

  • Author: Munck af Rosenschöld, P.

    Copenhagen University Hospital, Denmark

  • Author: Mouritsen, L. S.

    Copenhagen University Hospital, Denmark

  • Author: Due, A. K.

    Copenhagen University Hospital, Denmark

  • Author: Berthelsen, A. K.

    Copenhagen University Hospital, Denmark

  • Author: Nyman, J.

    Copenhagen University Hospital, Denmark

  • Author: Markova, E.

    Copenhagen University Hospital, Denmark

  • Author: Roed, A. P.

    Copenhagen University Hospital, Denmark

  • Author: Roed, H.

    Copenhagen University Hospital, Denmark

  • Author: Korreman, S.

    Copenhagen University Hospital, Denmark

  • Author: Specht, L.

    Copenhagen University Hospital, Denmark

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Objectives
In radiotherapy, delineation uncertainties are important as they contribute to systematic errors and can lead to geographical miss of the target. For margin computation, standard deviations (SDs) of all uncertainties must be included as SDs. The aim of this study was to quantify the interobserver delineation variation for stereotactic body radiotherapy (SBRT) of peripheral lung tumours using a cross-sectional study design.
Methods
22 consecutive patients with 26 tumours were included. Positron emission tomography/CT scans were acquired for planning of SBRT. Three oncologists and three radiologists independently delineated the gross tumour volume. The interobserver variation was calculated as a mean of multiple SDs of distances to a reference contour, and calculated for the transversal plane (SDtrans) and craniocaudal (CC) direction (SDcc) separately. Concordance indexes and volume deviations were also calculated.
Results
Median tumour volume was 13.0 cm3, ranging from 0.3 to 60.4 cm3. The mean SDtrans was 0.15 cm (SD 0.08 cm) and the overall mean SDcc was 0.26 cm (SD 0.15 cm). Tumours with pleural contact had a significantly larger SDtrans than tumours surrounded by lung tissue.
Conclusions
The interobserver delineation variation was very small in this systematic cross-sectional analysis, although significantly larger in the CC direction than in the transversal plane, stressing that anisotropic margins should be applied. This study is the first to make a systematic cross-sectional analysis of delineation variation for peripheral lung tumours referred for SBRT, establishing the evidence that interobserver variation is very small for these tumours.
Original languageEnglish
JournalBritish Journal of Radiology
Publication date2012
Volume85
Issue1017
Pagese654-e660
ISSN0007-1285
DOIs
StatePublished
CitationsWeb of Science® Times Cited: 2
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