Fig. 1

Workflow for mDelphi process: The mDelphi process was initiated at the EIBALL and EORTC Imaging Group steering committee levels. In Round 1 (blue workflow), 3 task forces were assigned (step 1) to deal with (i) modality and image acquisition, (ii) segmentation methodology itself, and (iii) standards and logistical issues. The task forces formulated survey questions and submitted them to the facilitator (step 2) who then distributed them to the participants (step 3), with the results being fed to the co-ordinator (step 4). In Round 2 (green workflow), the facilitator received (step 5) and amalgamated the responses and informed the task forces of the outcome so that they could devise a second round of questions and send them to the facilitator (step 6). These new questions were sent again to the participants of Round 1 (step 7) and responses collected by the coordinator (step 8). For Round 3 and iteratively for Round 4 (orange workflow), the responses received by the facilitator (step 9) were reviewed, and targeted questions were formulated towards achieving consensus and distributed again to participants (step 10). The final responses collected by the co-ordinator (step 11) were circulated to the EIBALL and EORTC Imaging Group steering committees (step 12) for review and analysis