Multiple training interventions significantly improve reproducibility of PET/CT-based lung cancer radiotherapy target volume delineation using an IAEA study protocol.

Background and purpose To assess the impact of a standardized delineation protocol and training interventions on PET/CT-based target volume delineation (TVD) in NSCLC in a multicenter setting. Material and methods Over a one-year period, 11 pairs, comprised each of a radiation oncologist and nuclear medicine physician with limited experience in PET/CT-based TVD for NSCLC from nine different countries took part in a training program through an International Atomic Energy Agency (IAEA) study (NCT02247713). Teams delineated gross tumor volume of the primary tumor, during and after training interventions, according to a provided delineation protocol. In-house developed software recorded the performed delineations, to allow visual inspection of strategies and to assess delineation accuracy. Results Following the first training, overall concordance indices for 3 repetitive cases increased from 0.57 ± 0.07 to 0.66 ± 0.07. The overall mean surface distance between observer and expert contours decreased from −0.40 ± 0.03 cm to −0.01 ± 0.33 cm. After further training overall concordance indices for another 3 repetitive cases further increased from 0.64 ± 0.06 to 0.80 ± 0.05 ( p = 0.01). Mean surface distances decreased from −0.34 ± 0.16 cm to −0.05 ± 0.20 cm ( p = 0.01). Conclusion Multiple training interventions improve PET/CT-based TVD delineation accuracy in NSCLC and reduce interobserver variation. [ABSTRACT FROM AUTHOR]