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Credentialing of radiotherapy centres in Australasia for TROG 09.02 (Chisel), a Phase III clinical trial on stereotactic ablative body radiotherapy of early stage lung cancer.

OBJECTIVE
A randomised clinical trial comparing stereotactic ablative body radiotherapy (SABR) with conventional radiotherapy for early stage lung cancer has been conducted in Australia and New Zealand under the auspices of the TransTasman Radiation Oncology Group (NCT01014130). We report on the technical credentialing program as prerequisite for centres joining the trial.


METHODS
Participating centres were asked to develop treatment plans for two test cases to assess their ability to create plans according to protocol. Dose delivery in the presence of inhomogeneity and motion was assessed during a site visit using a phantom with moving inserts.


RESULTS
Site visits for the trial were conducted in 16 Australian and 3 New Zealand radiotherapy facilities. The tests with low density inhomogeneities confirmed shortcomings of the AAA algorithm for dose calculation. Dose was assessed for a typical treatment delivery including at least one non-coplanar beam in a stationary and moving phantom. This end-to-end test confirmed that all participating centres were able to deliver stereotactic ablative body radiotherapy with the required accuracy while the planning study demonstrated that they were able to produce acceptable plans for both test cases.


CONCLUSION
The credentialing process documented that participating centres were able to deliver dose as required in the trial protocol. It also gave an opportunity to provide education about the trial and discuss technical issues such as four-dimensional CT, small field dosimetry and patient immobilisation with staff in participating centres. Advances in knowledge: Credentialing is an important quality assurance tool for radiotherapy trials using advanced technology. In addition to confirming technical competence, it provides an opportunity for education and discussion about the trial.