Conclusions
In this planning benchmark case, a number of major deviations were found in the first submission, and they were corrected after revision. The protocol compliance was significantly improved and was of high level in the final submission. The reduced variations will guarantee good RT plan quality and its inter-institutional consistency. The benchmark case results provided a valuable insight into the importance of pretrial QA, continuous education, communication through regular workshops, real-time central review, and feedback in multi-center clinical trials.