Matthew Dimmock

Introduction: Diagnostic reference levels (DRLs) are typical dose levels for medical imaging examinations for groups of standard‐sized patients or standard phantoms for broadly defined types of equipment used as a tool to aid optimisation of protection for medical exposures. Currently, there are no paediatric DRLs for conventional radiography (i.e. general X‐rays) published in Australia. The aim of this study was to establish typical radiation doses and risks that are representative of those delivered for commonly performed X‐ray projections for a 5‐year‐old/20 kg child using a 5‐year‐old anthropomorphic ‘bone fracture’ phantom in three dedicated paediatric radiology departments in Victoria. Methods: A total of 20 projection images were acquired for a standard 5‐year‐old/20 kg phantom using digital radiography X‐ray equipment. The air kerma‐area product (KAP) measured at each centre by a KAP metre, which was calibrated to a national primary standard, was considered to represent the median value for that centre for each X‐ray projection. Organ doses and effective dose were estimated using PCXMC software, and risks of radiation‐induced cancer and radiation‐induced death were calculated based on the BEIR VII report. Results: The typical doses for the individual X‐ray projections ranged from 3 mGy•cm 2 to 86 mGy•cm 2 , whilst the effective doses ranged from 0.00004 to 0.07 mSv. The radiation risks were ‘minimal’ to ‘negligible’. Conclusion: The estimation of typical radiation doses and associated risks for a 5‐year‐old/20 kg phantom study provides reference values for guidance and is a first step in assisting optimisation at other institutions until national DRLs, based on patient data from the clinical setting, are published.