Doctors' use of CT head scans for hospitalized patients didn't change when the prices were revealed at the time an order was being made. Wikimedia Commons hide caption

itoggle caption Wikimedia Commons

Isabel Doran, 4, gets a CT scan at Children's National Medical Center with her mom, Veronica Doran. The X-ray radiation in CT scans raises the risks for cancer, including leukemia, a new study shows. Dayna Smith/The Washington Post/Getty Images hide caption

itoggle caption Dayna Smith/The Washington Post/Getty Images

Dr. Steven Birnbaum positions a patient inside a CT scanner at Southern New Hampshire Medical Center in Nashua, N.H., in June 2010. Jim Cole/AP hide caption

itoggle caption Jim Cole/AP

Republican presidential candidate Gov. Rick Perry of Texas prepares to speak at a dinner in Bettendorf, Iowa, Monday. Two years ago Perry signed into Texas law an insurance mandate covering controversial tests for heart disease. Charlie Neibergall/AP hide caption

itoggle caption Charlie Neibergall/AP