People who had certain kinds of dental X-rays in the past may be at an increased risk for meningioma, the most commonly diagnosed brain tumor in the U.S., a new study suggests.

The findings cannot prove that radiation from the imaging caused the tumors, and the results are based on people who were likely exposed to higher levels of radiation during dental X-rays than most are today.

"It's likely that the exposure association we're seeing here is past exposure, and past exposure levels were much higher," said Dr. Elizabeth Claus, the study's lead author and a professor at the Yale School of Medicine in New Haven, Connecticut.

Claus and her colleagues write in the journal Cancer that dental X-rays are the most common source of exposure to ionizing radiation -- which has been linked to meningiomas in the past -- but most research on the connection is based on people who were exposed to atomic bombs or received radiation therapy.

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