A large West Virginia hospital seriously overradiated patients suspected of having strokes with CT scans for more than a year after similar episodes prompted federal officials to alert hospitals nationwide to be especially careful when using those types of scans, interviews and documents show.

The patients, at Cabell Huntington Hospital in Huntington, W.Va., were overdosed with radiation until late November, records show, even after the Food and Drug Administration had publicly issued its final report on hundreds of overdoses involving brain scans at other hospitals and the errors had been discussed publicly in Congress and by state officials and professional organizations.

Federal records indicate that Cabell knew of some of the overdoses for three months, but it did not disclose them publicly until The New York Times called the hospital for comment late last week. Within hours, the hospital issued a news release that was picked up by the local media.

Charles Shumaker, a hospital spokesman, declined to say how many patients were overdosed, why the mistakes occurred or whether any hospital employees were disciplined as a result.