National audit maps radiotherapy’s hits and misses in cancer care

The accuracy of stereotactic body radiotherapy (SBRT), a modern radiotherapy technique increasingly used for cancer care across Australia, has come under an audit by the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA)

Each year, around 90,000 patients nationwide undergo radiotherapy. SBRT has become an established treatment for early-stage lung, prostate, and liver cancers, as well as oligometastatic disease, offering patients fewer treatment sessions with highly targeted, higher doses.

The audit was conducted across a range of technologies, including conventional Varian and Elekta Linear Accelerators, Varian Halcyon Linear Accelerators, and TomoTherapy and CyberKnife systems. It evaluated when best practice was achieved while minimising damage to surrounding healthy tissues and organs.

Dr Andrew Alves, ARPANSA’s medical physics lead and study author, explained how advances in radiotherapy technology are transforming clinical practice.

“Higher dose treatment, known as hypofractionated radiotherapy means fewer visits to the clinic,” Dr Alves said. “When the high dose radiation is on target it kills tumour cells and spares healthy organs and tissues; however, the margin for error for this approach is low. That’s why we’ve developed a customised audit to validate patient dose for this treatment.”

Using an artificial ‘patient’ (phantom), the audit assessed how well Australian and New Zealand clinics deliver treatment, measuring accuracy within strict tolerances – ±2 mm in position and ±5% in dose. The study examined radiotherapy accuracy in spine, lung, and soft tissue cases.

Because one of the drivers behind this audit design was clinical trial credentialing, the findings provide strong confidence in SBRT clinical trial outcomes during and after the study period.

Notably, some treatments fell outside tolerance levels due to dosimetric and positional delivery inaccuracies. Of these out-of-tolerance results in the audit, 44% were resolved after repeat measurement, with initial failures linked to Image Guided Radiation Therapy (IGRT) mismatches or machine isocentre misalignments.

Overall, soft tissue cases performed best with an out-of-tolerance rate of 3.6% (10/281), while more complex spine and lung cases recorded higher rates at 10% (23/238) and 10.3% (27/263) respectively. These figures, although notable, remain in line with international benchmarks from the Imaging and Radiation Oncology Core (IROC), which reported 15% and 22% failure rates for spine and lung audits.

Australian Clinical Dosimetry Service director, Rhonda Brown, who oversaw the study, highlighted its direct impact on patient outcomes.

“There are many benefits to using hypofractioned radiotherapy – including that clinics can treat more patients because people need fewer radiation doses with this treatment approach” Brown said.

“As the Australian Government’s primary radiation protection authority, and lead radiotherapy audit service in the country, we want to help ensure treatments are curing patients and not causing harm. This study looked at over 700 treatments and can be used not only as a benchmark in Australia but across the world.”

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