Abstract
Purpose
There has been increasing use of external beam radiotherapy for localized treatment of hepatocellular carcinoma (HCC) with both palliative and curative intent. Quality control of target delineation in primary HCC is essential to deliver adequate doses of radiation to the primary tumor while preserving adjacent healthy organs. We analyzed interobserver variability in gross tumor volume (GTV) delineation for HCC.
Patients and methods
Twelve radiation oncologists specializing in liver malignancy participated in a multi-institutional contouring dummy-run study of nine HCC cases and independently delineated GTV on the same set of provided computed tomography images. Quantitative analysis was performed using an expectation maximization algorithm for simultaneous truth and performance level estimation (STAPLE) with kappa statistics calculating agreement between physicians. To quantify the interobserver variability of GTV delineations, the ratio of the actual delineated volume to the estimated consensus volume (STAPLE), the ratio of the common and encompassing volumes, and the coefficient of variation were calculated.
Results
The median kappa agreement level was 0.71 (range 0.28–0.86). The ratio of the actual delineated volume to the estimated consensus volume ranged from 0.19 to 1.93 (median 0.94) for all cases. The ratio of the common and encompassing volumes ranged from 0.001 to 0.56 (median 0.25). The coefficient of variation for GTV delineation ranged from 8 to 57 % (median 26 %).
Conclusion
The interobserver variability in target delineation of HCC GTV in this study is noteworthy. Multi-institution studies involving radiotherapy for HCC require appropriate quality assurance programs for target delineation.
Zusammenfassung
Ziel
Die externe kurative Strahlentherapie ist zunehmend bei der lokalisierten Behandlung hepatozellulärer Karzinome (HCC) in palliativer und kurativer Absicht in Gebrauch. Eine Qualitätskontrolle der Zielabgrenzung beim primären HCC ist entscheidend, um die passende Dosis für die Primärtumorbestrahlung zuzuführen und gesunde benachbarte Organe zu schonen. Wir analysierten die Interobservervariabilität in Abgrenzung zum makroskopischen Tumorvolumen (GTV) beim HCC.
Patienten und Methoden
In einer institutsübergreifenden konturierenden Teststudie mit 9 HCC-Fällen beschrieben 12 Strahlentherapeuten das GTV anhand des gleichen Satzes von zur Verfügung gestellten Computertomogrammen. Die quantitative Analyse wurde unter Verwendung eines Expectation-Maximization-Algorithmus für die „Simultaneous Truth and Performance Level Estimation“ (STAPLE) in Verbindung mit einer zwischen den Ärzten vereinbarten Berechnung von Kappa-Statistiken durchgeführt. Um die Interobservervariabilität der GTV-Abgrenzung zu bestimmen, wurden das Verhältnis des tatsächlich abgegrenzten Volumens zum geschätzten Konsensvolumen (STAPLE), das Verhältnis des gemeinsamen Volumens zum umfassenden Volumen sowie der Variationskoeffizient berechnet.
Ergebnisse
Das mediane Kappa-Agreement-Level betrug 0,71 (Spanne 0,28–0,86). Das Verhältnis des tatsächlich abgegrenzten Volumens zum geschätzten Konsensvolumen lag in sämtlichen Fällen zwischen 0,19 und 1,93 (Mittelwert 0,94). Das Verhältnis des gemeinsamen Volumens zum umfassenden Volumen lag zwischen 0,001 und 0,56 (Mittelwert 0,25). Der Variationskoeffizient für die GTV-Abgrenzung lag im Bereich von 8–57 % (Mittelwert 26 %).
Schlussfolgerung
Die Interobservervariabilität in der Zielabgrenzung des HCC-GTV ist in dieser Studie bemerkenswert. Institutsübergreifende Studien für eine HCC-Strahlentherapie erfordern geeignete Qualitätssicherungsprogramme für die Zielabgrenzung.
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Acknowledgements
This work was supported by a grant (0620390) from the National R&D Program for Cancer Control, Ministry of Health and Welfare, Republic of Korea.
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Y.S. Kim, J.W. Kim, W.S. Yoon, M.K. Kang, I.J. Lee, T.H. Kim, J.H. Kim, H.-S. Lee, H.C. Park, H.S. Jang, C.S. Kay, S.M. Yoon, M.-S. Kim, and J. Seong declare that they have no competing interests.
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All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study.
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Young Suk Kim and Jun Won Kim contributed equally.
Caption Electronic Supplementary Material
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Supplementary fig. 1: Patient 1. The 95 % confidence level (S95) is shown in thicker red line. Lipiodol deposit after transarterial chemoembolization (TACE) presented with high-density nodule
66_2016_1028_MOESM2_ESM.tif
Supplementary fig. 2. Patient 2. The 95 % confidence level (S95) is shown in thicker red line. Tumor-to-parenchyma difference is minimal
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Kim, Y.S., Kim, J.W., Yoon, W.S. et al. Interobserver variability in gross tumor volume delineation for hepatocellular carcinoma. Strahlenther Onkol 192, 714–721 (2016). https://doi.org/10.1007/s00066-016-1028-2
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DOI: https://doi.org/10.1007/s00066-016-1028-2