From 2001 to 2010,the percentage of emergency department visits with a CT or MRI test ordered or if nearly tripled from 6% to 17%, and the percentage of visits with an ultrasound ordered or if doubled from 2% to 4%. The percentage of emergency department visits with a radiograph ordered or if did not change significantly. Throughout the period, and the percentage of visits with a radiograph was higher than the percentage with a CT/MRI or ultrasound combined and remained steady at approximately 35%.
Source: cdc.gov