Interobserver delineation uncertainty in involved-node radiation therapy (INRT) for early-stage Hodgkin lymphoma: On behalf of the Radiotherapy Committee of the EORTC lymphoma group

Aznar, M. C., Girinsky, T., Berthelsen, A. K., Aleman, B. M., Beijert, M., Hutchings, M., Lievens, Y., Meijnders, P., Petersen, P. M., Schut, D., Maraldo, M. V., van der Maazen, R. W. & Specht, L., 2017, In : ACTA ONCOLOGICA. 56, 4, p. 608-613 6 p.

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  • Interobserver delineation uncertainty in involved node radiation therapy INRT for early stage Hodgkin lymphoma on behalf of the Radiotherapy

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  • Marianne C. Aznar
  • Theodore Girinsky
  • Anne Kiil Berthelsen
  • Berthe M. Aleman
  • Max Beijert
  • Martin Hutchings
  • Yolande Lievens
  • Paul Meijnders
  • Peter Meidahl Petersen
  • Deborah Schut
  • Maja V. Maraldo
  • Richard W. van der Maazen
  • Lena Specht

Background and purpose: In early-stage classical Hodgkin lymphoma (HL) the target volume nowadays consists of the volume of the originally involved nodes. Delineation of this volume on a post-chemotherapy CT-scan is challenging. We report on the interobserver variability in target volume definition and its impact on resulting treatment plans.Materials and methods: Two representative cases were selected (1: male, stage IB, localization: left axilla; 2: female, stage IIB, localizations: mediastinum and bilateral neck). Eight experienced observers individually defined the clinical target volume (CTV) using involved-node radiotherapy (INRT) as defined by the EORTC-GELA guidelines for the H10 trial. A consensus contour was generated and the standard deviation computed. We investigated the overlap between observer and consensus contour [SOrensen-Dice coefficient (DSC)] and the magnitude of gross deviations between the surfaces of the observer and consensus contour (Hausdorff distance). 3D-conformal (3D-CRT) and intensity-modulated radiotherapy (IMRT) plans were calculated for each contour in order to investigate the impact of interobserver variability on each treatment modality. Similar target coverage was enforced for all plans.Results: The median CTV was 120cm(3) (IQR: 95-173cm(3)) for Case 1, and 255cm(3) (IQR: 183-293cm(3)) for Case 2. DSC values were generally high (>0.7), and Hausdorff distances were about 30mm. The SDs between all observer contours, providing an estimate of the systematic error associated with delineation uncertainty, ranged from 1.9 to 3.8mm (median: 3.2mm). Variations in mean dose resulting from different observer contours were small and were not higher in IMRT plans than in 3D-CRT plans.Conclusions: We observed considerable differences in target volume delineation, but the systematic delineation uncertainty of around 3mm is comparable to that reported in other tumour sites.This report is a first step towards calculating an evidence-based planning target volume margin for INRT in HL.

Original languageEnglish
Pages (from-to)608-613
Number of pages6
Issue number4
Publication statusPublished - 2017



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