PLoS ONE (Jan 2016)

Harmonization of the Volume of Interest Delineation among All Eleven Radiotherapy Centers in the North of France.

  • David Pasquier,
  • Laurence Boutaud de la Combe-Chossiere,
  • Damien Carlier,
  • Franck Darloy,
  • Anne Catherine Degrendel-Courtecuisse,
  • Chantal Dufour,
  • Mustapha Fares,
  • Laurent Gilbeau,
  • Xavier Liem,
  • Philippe Martin,
  • Pascal Meyer,
  • Jean François Minne,
  • Olimpia Olszyk,
  • Hassan Rhliouch,
  • Marc Tokarski,
  • Chloé Viot,
  • Bernard Castelain,
  • Eric Lartigau

DOI
https://doi.org/10.1371/journal.pone.0150917
Journal volume & issue
Vol. 11, no. 3
p. e0150917

Abstract

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BACKGROUND:Inter-observer delineation variation has been detailed for many years in almost every tumor location. Inadequate delineation can impair the chance of cure and/or increase toxicity. The aim of our original work was to prospectively improve the homogeneity of delineation among all of the senior radiation oncologists in the Nord-Pas de Calais region, irrespective of the conditions of practice. METHODS:All 11 centers were involved. The first studied cancer was prostate cancer. Three clinical cases were studied: a low-risk prostate cancer case (case 1), a high-risk prostate cancer case (pelvic nodes, case 2) and a case of post-operative biochemical elevated PSA (case 3). All of the involved physicians delineated characteristically the clinical target volume (CTV) and organs at risk. The volumes were compared using validated indexes: the volume ratio (VR), common and additional volumes (CV and AV), volume overlap (VO) and Dice similarity coefficient (DSC). A second delineation of the same three cases was performed after discussion of the slice results and the choice of shared guidelines to evaluate homogenization. A comparative analysis of the indexes before and after discussion was conducted using the Wilcoxon test for paired samples. A p-value less than 0.05 was considered to indicate statistical significance. RESULTS:The indexes were not improved in case 1, for which the inter-observer agreement was considered good after the first comparison (DSC = 0.83 ± 0.06). In case 2, the second comparison showed homogenization of the CTV delineation with a significant improvement in CV (81.4 ± 11.7 vs. 88.6 ± 10.26, respectively, p = 0.048), VO (0.41 ± 0.09 vs. 0.47 ± 0.07, respectively; p = 0.009) and DSC (0.58 ± 0.09 vs. 0.63 ± 0.07, respectively; p = 0.0098). In case 3, VR and AV were significantly improved: VR: 1.71(± 0.6) vs. 1.34(± 0.46), respectively, p = 0.0034; AV: 46.58(± 14.50) vs. 38.08(± 15.10), respectively, p = 0.0024. DSC was not improved, but it was already superior to 0.6 in the first comparison. CONCLUSION:Our prospective work showed that a collaborative discussion about clinical cases and the choice of shared guidelines within an established framework improved the homogeneity of CTV delineation among the senior radiation oncologists in our region.