MO‐D‐105‐04: A Nation‐Wide Three Level Audit Service ‐ the Australian Experience

Abstract

In February 2011, the Australian Government launched the Australian Clinical Dosimetry Service (ACDS) a three year trial of an independent dosimetric auditing service for Australia. The ACDS has designed and implemented a three level audit program, each succeeding level with a more complex and challenging geometry. It is similar to other audit programs internationally, but is unique in its coverage, national participation (voluntary and free service), audit design and final review process. The ACDS has utilised existing audit protocols, adapted and expanded components of those as needed. The final protocols have been rigorously tested inhouse. The Level I audit is a remotely conducted point dose verification under reference conditions. It was introduced using TLD detectors and has been transitioned to OSLD, following validation of the OSLD technology and setup. By August 2013, each clinical linac in Australia will have received at least one Level I photon beam audit. The Level II audit investigates treatment planning and delivery using a synthetic CT data set and planar array measurements in different geometries. It tests the components treatment planning and linac dose delivery independent of the CT imaging.The Level III audit is an end‐to‐end test. An anthropomorphic phantom is taken through the complete chain of procedures experienced by a patient in a radiotherapy facility. In their first implementation the ACDS Level II and III audits, which are performed by an onsite team, investigate inhomogeneities, wedges and asymmetric fields. Additionally, the Level Ib has been implemented as an onsite reference geometry audit. It uses the facility's watertank and otherwise independent equipment to verify dose delivery for all beams under reference conditions. This audit has been very popular for new installations. Audit design philosophy, tolerance levels, results, lessons learned and future directions (intensity modulated/rotational therapy, flattening‐filter free beams, SRS) will be reviewed and discussed. The Australian Clinical Dosimetry Service is a joint initiative between the Australian Department of Health and Ageing and the Australian Radiation Protection and Nuclear Safety Agency