Imaging, like x-rays and CT scans, are routine, non-invasive, and painless tools for doctors to make diagnoses.

But a recent study of about 4 million U.S. and Canadian children published in the New England Journal of Medicine

suggests that the radiation exposure from imaging could pose a risk.

It estimates that about 10% of blood cancers

like leukemia and lymphoma in the study group may have been attributable to radiation exposure

from medical imaging. Dr. Rebecca Smith Bindman is the lead author of the study, and she's a professor

at the University of California, San Francisco.

Dr. Smith-Bindman, is this the first time, first study to focus on children and in such a large scale? It is. It's the first study that looks at children in all kinds of medical tests that

they observe, and then we follow those children for a long period of time. We added up their cumulative

dose of radiation from all those tests, identified which children were diagnosed with

heminologic cancer to allow us to estimate the risks of those exams.

Are children particularly vulnerable to exposure to radiation?

They are. They're vulnerable, we think, for two reasons.

First, because they have a long life expectancy in front of them,

and the risk of developing a cancer from radiation is cumulative over time,

and the risk lasts a whole lifetime.

But also, their cells are rapidly dividing, they're growing, and that makes

them particularly vulnerable to the kind of damage that's caused by the radiation.

The studies I understand it said that even low levels of radiation from one or two CT scans

can increase the risk. What's the significance of that?

It's not just CT scans that increase the risk. It's all significance of that? It's not just CT scans that increase the risk.

It's all kinds of radiation. So we use radiation from all different kinds of medical tests,

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