Background and study aims: Computerised Tomography (CT) head scans are frequently requested by Emergency Department (ED) clinicians as one of the investigations for their patients. This often causes a delay when waiting for specialist radiologists to report the findings of the scan. The purpose of this study is to see if online training can improve the ability of ED clinicians to interpret the scans themselves, to a level sufficient to make clinical decisions based on their findings and to explore what aspects of this process they find most challenging. Participants: Emergency Department clinicians who are working in the Emergency Departments of participating sites between April to September 2022 (inclusive), who request CT Head scans as part of their routine clinical practice. What does the study involve?: 180 ED clinicians will be recruited across 6 hospital sites in the United Kingdom. All will undertake a baseline online assessment to measure their accuracy in interpreting CT head scans. One group will then undertake an online training module, with a subsequent assessment immediately afterwards, then over the following 3 months will record interpretations for 30 CT head scans. Head images encountered in participants' routine clinical practice, and their findings, will be compared with the radiology reports for each scan. Participants will then undertake further online assessments 3 and 6 months after the start of the study. Their overall results will be compared with a control group, who will undergo the same process, but undertake the online training after they have tried to interpret 30 scans in their clinical practice. Participants will continue to base their clinical decisions on radiologist reports, not their own interpretations, so patient care will not be affected by this study.