Interobserver variability of clinical target volume delineation in supra-diaphragmatic Hodgkin's disease: a multi-institutional experience.

ABSTRACT

BACKGROUND: To determine interobserver variability in clinical target volume (CTV) of supra-diaphragmatic Hodgkin's lymphoma. MATERIALS AND METHODS: At the 2008 AIRO (Italian Society of Radiation Oncology) Meeting, the Radiation Oncology Department of Chieti proposed a multi-institutional contouring dummy-run of two cases of early stage supra-diaphragmatic Hodgkin's lymphoma after chemotherapy. Clinical history, diagnostics, and planning CT imaging were available on Chieti's radiotherapy website (www.radioterapia.unich.it). Participating centers were requested to delineate the CTV and submit it to the coordinating center. To quantify interobserver variability of CTV delineations, the total volume, craniocaudal, laterolateral, and anteroposterior diameters were calculated. RESULTS: A total of 18 institutions for case A and 15 institutions for case B submitted the targets. Case A presented significant variability in total volume (range 74.1-1,157.1 cc), craniocaudal (range 6.5-22.5 cm; median 16.25 cm), anteroposterior (range 5.04-14.82 cm; median 10.28 cm), and laterolateral diameters (range 8.23-22.88 cm; median 15.5 cm). Mean CTV was 464.8 cc (standard deviation 280.5 cc). Case B presented significant variability in total volume (range 341.8-1,662 cc), cranio-caudal (range 8.0-28.5 cm; median 23 cm), anteroposterior (range 7.9-1.8 cm; median 11.1 cm), and laterolateral diameters (range 12.9-24.0 cm; median 18.8 cm). Mean CTV was 926.0 cc (standard deviation 445.7 cc). CONCLUSION: This significant variability confirms the need to apply specific guidelines to improve contouring uniformity in Hodgkin's lymphoma.