A new study suggests that a type of "super X-ray" can give a faster, cheaper way to tell whether a chest pain sufferer is really having a heart attack.

About 6 million Americans go to emergency rooms each year with chest pain, but only a small fraction are having a heart attack. Powerful X-rays called CT scans are being used more often to help make the diagnosis. Doctors don't know yet whether their accuracy and other benefits outweigh the additional radiation they require over standard tests.

The new study finds that testing with CT scans gives an answer in about three hours versus more than six hours for the usual diagnosis using other types of tests. CT scans also cost less. Results were given Wednesday at an American Heart Association conference.