body scanners have made their way into airports across the u.s. a number of these use x-ray, and others use millimeter-wave technology.
the e.u. has banned these machines over concerns that the x-ray radiation exposure and associated cancer risks may not be as insignificant as originally purported.
the e.u. is using millimeter-wave scanners, which have not been identified ask having a link to cancer.
EU Bans Airport X-Ray Machines
EU Bans Airport X-Ray Scanners Over Health Concerns | Mother Jones
regardless of the type of body scanner used, you can opt for a pat down rather than risk exposure to any sort of radiation. for children, because their body mass is smaller, the risk may be more substantive.
give yourself plenty of time when clearing airport security. i try to get into the line that has the old metal detector and not the new body scanners. if you do end up in a line that has a body scanner, tell them you don't want to be scanned. they will get someone to pat you down. i once had to wait some time at the security line for someone to come and perform the pat down - this is why you want to make sure you have plenty of time.
also be aware that if you've traveled through other places where a pat down is common, like in india, the folks who perform pat downs in the u.s. can be a tad more thorough.