Valtchinov VI, et al. - In this retrospective cohort study involving 56,793 patients, researchers analyzed the magnitude of physician variation in imaging use and the factors associated with urban emergency department (ED) variation in the U.S. According to results, the coefficient of variation for adjusted imaging odds ratios was 10.9% and 14.0% respectively for low-cost and high-cost imaging, indicating a moderate degree of variation. Findings revealed that there is unexplained and moderate variation in the use of images among ED doctors, even after controlling the characteristics of the patient, visit, and physician. Improving initiatives using well-defined measurements of ED imagery quality can help improve quality and reduce waste.