According to the researchers at the Institute for Clinical Evaluative Sciences, Toronto, around 25% of CT scans are prescribed for patients with headaches, but only a handful of tests actually diagnose the cause.

The researchers examined as many as 3,930 outpatient CT scans in Ontario in the year 2005 on patients with an average age of 45.

The lead researcher of the study, Dr. John You noticed that out of 623 patients who received the scans, only 2% scans were found to have something responsible for causing the pain.

The co-author of the study, Dr. Jonathan Gladstone of the Cleveland Clinic Canada, Toronto said that a headache is considered to be the most common reasons patients visit their family doctor, go to emergency, or consult a neurologist.

Experts are concerned that exposure to radiation during the CT scans can increase the public health risk.

It is also noted that patients suffering from migraines or those who experience headaches four or five days in a month usually require less CT scanning of the brain. But those who have persistent headaches for months require CT scanning of the brain.

The study findings will be published in the October online edition of the American Journal of Medicine.