The Quality Assurance programme of the Radiotherapy Group of the European Organization for Research and Treatment of Cancer (EORTC): a critical appraisal of 20 years of continuous efforts.

In 1982, the European Organization for Research and Treatment of Cancer (EORTC) Radiotherapy Group established the Quality Assurance (QA) programme. During the past 20 years, QA procedures have become a major part of the activities of the group. The methodology and steps of the QA programme over the past 20 years are briefly described. Problems and conclusions arising from the results of the long-lasting QA programme in the EORTC radiotherapy group are discussed and emphasised. The EORTC radiotherapy group continues to lead QA in the European radiotherapy community. Future challenges and perspectives are proposed.