Radiotherapy dosimetry audits carried out in Ireland at the request of the National Radiation Safety Committee in 2014 & 2017.

PURPOSE: Two requests were issued by Ireland's National Radiation Safety Committee (NRSC) to radiotherapy centres in Ireland to participate in external dosimetry audits in order to demonstrate compliance with the requirement for clinical audit in medical radiological procedures. METHODS: Centres were requested to carry out the phantom irradiation offered by the MD Anderson Dosimetry Laboratory (MDADL) for prostate IMRT in 2014 and were subsequently requested to irradiate the same organisation's head and neck phantom in 2017. RESULTS: A total of 22 audits were performed across 11 radiotherapy centres, capturing the full range of planning and c-arm linear accelerator combinations in use in Ireland at the time of the audits. The mean MDADL vs. institution measured dose for Planning Target Volume (PTV) points was 0.999 ±â€¯0.026 (1SD). The mean PTV gamma pass rate (and lower 95% confidence interval) at 7%/4 mm was 97% (90%). A significant difference was observed between prostate and head and neck irradiations but for no other subdivisions of data e.g. fixed gantry angle IMRT and VMAT. CONCLUSION: Radiotherapy centres in Ireland participated in a co-ordinated set of external audits with all centres satisfying the phantom irradiation component of the MDADL credentialing process.