Summary of 2001 data. Summary of 2001 data. All patients with head injuries (HI) for the seven month control period are included. Royal College of Surgeons guideline for CT was in operation when the patients were treated. The Canadian CT rule for CT was applied retrospectively to determine how many patients would fulfil it. *Two sets of case notes were not available and could not be confidently include in this part of the analysis. H Y Sultan et al. Emerg Med J 2004;21:420-425 Copyright © BMJ Publishing Group Ltd and the College of Emergency Medicine. All rights reserved.