Demonstrating the clinical impact of auditing-update from the Australian Clinical Dosimetry Service

Purpose: The Australian Clinical Dosimetry Service (ACDS) has been auditing Australian and New Zealand radiotherapy providers for nearly 10 years building the National Dataset of audit measurements. The audits have uncovered numerous issues with varying significance. This paper will present an update of the ACDS audits including trends within the National Dataset and recent audit findings and will then cover recent audit of more advanced modalities such as SRS, SBRT, VMAT and adaptive radiotherapy. The presentation will conclude with a summary of the COVID-19 impact on the ACDS. The audits demonstrably improve the treatment quality and safety for patients undergoing radiotherapy. Methods and Materials: The ACDS began life in November 2010 and has developed a comprehensive three level auditing service which has expanded beyond Australia's borders. To minimize dosimetric uncertainties the ACDS has been using Computerized Imaging Reference Systems (CIRS)1 plastic water and phantoms across all on-site audits. As phantom complexity increased to meet auditing needs, CIRS was engaged to produce bespoke phantoms for the ACDS. The most recent examples of this are the Stereotactic Radio-Surgery (SRS) head phantom, SBRT, and a thorax customized for stereotactic ablative radiotherapy (SABR) auditing. Results: Audits provide two key outcomes for participating facilities. The first is that independent measurements demonstrate whether the facility's predicted dose is being delivered to the phantom within an acceptable tolerance. For an out-of-tolerance finding the ACDS works with the facility to resolve any discrepancies on the day of audit. Examples include inaccurate data entry in a planning system or inaccurate phantom positioning. Sometimes, however, there may be a systemic issue with calculation algorithms. The National Dataset has enables the ACDS to identify characteristic behavior of certain equipment combinations. As the ACDS perform more audits, the statistical power of the dataset increases and trends can be identified. This is the second key capability which a mature auditor provides to the auditee. Conclusion: The ACDS has development a coherent and successful auditing service which is proactively responding to changing technologies and environment.