Aside from X-rays, radiology departments perform procedures that may involve dyes, sedatives and blood thinners.
The United States Pharmacopeia study found radiology departments were responsible for 12 percent of mistakes that caused harm to patients vs. 1.67 percent for all harmful hospital drug errors -- most often because information was not passed from department to department.
"We hope that this report is a call to action," the nonprofit standards group's John Santell told The Washington Post.
"Every hospital in the United States ought to be taking a look at this," said Michael Cohen, Institute for Safe Medication Practices president.
"Whenever a patient is moved from one location to another, the patient should ask where they are going and why," Santell said.
Critics said the study counts all radiology errors even though some have nothing to do with the 570 million radiology procedures performed each year.