Catharine H Clark, Edwin GA Aird, Steve Bolton, Elizabeth A Miles, Andrew Nisbet, Julia AD Snaith, Russell AS Thomas, Karen Venables, David I Thwaites

Dosimetry audit plays an important role in the development and safety of radiotherapy. National and large scale audits are able to set, maintain and improve standards, as well as having the potential to identify issues which may cause harm to patients. They can support implementation of complex techniques and can facilitate awareness and understanding of any issues which may exist by benchmarking centres with similar equipment. This review examines the development of dosimetry audit in the UK over the last 30 years, including the involvement of the UK in international audits. A summary of audit results is given, with an overview of methodologies employed and lessons learnt. Recent and forthcoming more complex audits are considered, with a focus on future needs including the arrival of proton therapy in the UK and other advanced techniques such as 4D radiotherapy delivery and verification, stereotactic radiotherapy and MR linacs. The work of the main quality assurance and auditing bodies is discussed, including how they are working together to streamline audit and to ensure that all radiotherapy centres are involved. Undertaking regular external audit motivates centres to modernise and develop techniques and provides assurance, not only that radiotherapy is planned and delivered accurately, but that the patient dose delivered is as prescribed.