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Case study 3: MR-Linac

ARPANSA’s Australian Clinical Dosimetry Service (ACDS) plays an important role in the protection of cancer patients from the harmful effects of radiation through the auditing of radiotherapy facilities. The ACDS audit function helps radiotherapy providers ensure the accuracy of radiation doses delivered to patients in their care.

With the development of new technologies to deliver radiotherapy, it is important that ARPANSA continues to establish new techniques to audit radiation dose.

One example of new technology is the magnetic resonance imaging-linear accelerator, or MR-Linac. This technology combines the diagnostic capabilities of a MR scanner with a radiotherapy linear accelerator to improve the precision and effectiveness of radiation therapy treatment. This financial year saw the installation of Australia’s first MR-Linac in Townsville, Queensland. The ACDS team was able to audit the new machine prior to the treatment of any patients. Conducting the audit before clinical use provided strong quality assurance for the radiation oncology facility and confidence in the accuracy of the dose received for future patients.

The MR-Linac audit technique was developed in collaboration with local and international institutions after the completion of a year-long development program. This included an earlier visit by ARPANSA to the United Kingdom to undertake measurements using a working machine.

ACDS has developed Level 1b and Level III audits adapted to suit the conditions and function of an MR-Linac. The Level 1b audit involves on-site visits to perform measurements using ACDS dosimetry equipment and the Level III audit involves an end-to-end test which uses a human-like manikin simulating a real-life patient undergoing all steps in the radiotherapy treatment chain.

The development of specialised audit techniques for MR-Linacs is an important achievement for ARPANSA and its continuing role in the safety of patients receiving radiation as part of their medical treatment.