This episode reviews the article that most people call the PECARN head CT rule or the Kupperman head CT rule (named for the first author). This is an easy to use clinical decision rule that can help us reduce the number of head CTs that we do on children with minor head injury. We owe it to our patients to spare them excess radiation, cost, and time in the ED and this rules helps us do this. In order to use this rule effectively, you need to read this article and understand how the study was done. This allows us to understand the strengths and weaknesses of this rule and helps us apply it in our everyday practice.