This multicenter study has two primary aims; (1) we will assess Emergency Department-level variation in the use of CT scanning of the brain (CTB) in the diagnosis of children with mild head injury in tertiary, urban, and rural/regional hospitals in Australia and NZ, and identify potential hospital and/or patient level factors associated with CTB use; (2) we will identify and explore the clinician and organisational related factors influencing the use of CTB at participating Emergency Departments in children with head injuries and determine resource availability and need.

Each site will conduct a medical record audit to extract data relating to children who have presented with a head injury to the emergency department in 2016. Data will be extracted using a case report and entered into a web-based database.  Qualitative semistructured interviews will be conducted with invited doctors and nurses who treat children in the participating EDs, via telephone using a semi-structured interview proforma based on the Theoretical Domains Framework.