Massachusetts ? A good mammogram reader may do just as well at spotting cancers without expensive new computer systems often used for a second opinion, a new study suggests. Computerized mammography, now used for about a third of the nation’s mammograms, too often finds harmless spots that lead to false scares, researchers found.

The study of more than 429,000 mammograms found that “computer-aided detection” systems did not help radiologists find more tumors and significantly increased the number of false alarms.

The researchers and others said the findings, published in today’s issue of the New England Journal of Medicine, show that the expensive systems should undergo more scrutiny.

“There’s a tendency to say the newest technology has got to be better,” said Russell Harris of the University of North Carolina at Chapel Hill. “That’s not necessarily the way it works. This appears to be an example of that.”