Diagnostic accuracy of radiographers’ red dot usage in the emergency department

To investigate the accuracy of radiographers applying the ‘Red Dot System’ after completing a 10-week online image interpretation course and whether observer confidence plays a role in diagnostic performance. Eligible participating radiographers undertook diagnostic accuracy testing. Tests involved a review of an anonymised historic trauma image set, and participants were asked to apply a ‘red dot’ to study radiographs if a radiographic pathology was evident. The diagnostic accuracy of radiographers' red dot ability was evaluated by generating a sensitivity, specificity and accuracy score for each participant. A Receiver Operating Curve (ROC) was also compiled to evaluate the participants' ability and confidence in discriminating the presence or absence of pathology. A total of 700 cases were analysed. Fourteen participating radiographers had an overall red dot (case-based) sensitivity, specificity and accuracy of 85%, 86% and 85%, respectively. Positive and negative predictive values (PPV/NPV) were both 86%. Radiographers’ pathology-based sensitivity, specificity, and accuracy were 87%, 79%, and 83%, respectively. A resultant ROC curve generated an Area Under the Curve (AUC) value of 0.7. Compared to the literature, participating radiographers’ red dot skills could be considered acceptable but would benefit from improvement. We recommend that future work be carried out whereby participants at the study institution engage in a period of self-audit of their red dot practice and undertake additional diagnostic accuracy tests.