Amid the flap about radiation exposure from the new imaging devices at airport security checkpoints, a more common source gets a lot less attention. U.S. kids now receive an average of seven medical imaging tests that expose them to radiation by the time they are 18 years old, a study released this week by the University of Michigan suggests.

The study’s authors are quick to stress, however, that these tests are often necessary. “These tests are still an important part of medical care, and we’re definitely not saying that they shouldn’t be done,” says study co-author Adam L. Dorfman, M.D., a professor of radiology at U-M Medical School. Instead, Dorfman and others advocate a more thoughtful approach to medical imaging.

Dorfman says that radiation exposure is a concern in children for two main reasons: First, the cells in children’s bodies are dividing more rapidly than those in adults, leaving more chance for radiation to create anomalies. Second, radiation exposure accumulates over a lifetime, and the health problems it creates (i.e. cancer) aren’t likely to arise for decades. “If you’re 2, you have a lot more time for those problems to show up,” Dorfman says.

But whether it’s a chest x-ray to scan the lungs of a child with a serious cough, or a CT scan of the head after a bicycle accident, there’s a good chance most parents will find themselves taking their child in for an imaging test that involves radiation at some point. To make sure your child gets the care she needs while keeping her radiation exposure to a minimum, Dorfman suggests asking the following questions if your child is referred for an imaging test:

• Is there a clear medical benefit to this test? In other words, if it does show something, will that change how the child is treated?
• Do you use the lowest amount of radiation possible?
• Is there any kind of test that doesn’t use radiation that would be a reasonable alternative? Sometimes an ultrasound or MRI will do the trick.

Dorfman also suggests checking out ImageGently.org, a site from The Alliance for Radiation Safety In Pediatric Imaging. It features information and resources for both parents and professionals, and even offers a handy printable Medical Imaging Record you can keep for your child, so you can track all your child’s tests in one place. Parents, Dorfman says, are key in helping keep children’s imaging radiation exposure as low as possible. “Advocate for your children,” he urges. “Be involved in your children’s care and ask those questions.”