Scanners pose little risk

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300 full body scanners will soon be in airports across the country, but should we be concerned about dangerous radiation exposure, particularly for people who fly very frequently?　 We’re paging our chief medical correspondent Dr. Sanjay Gupta this morning.　 He’s in Atlanta.　 Well Doc, what’s the verdict here?

Well, good morning, yeah, this is something that I think about quite a bit as well, given how much we all travel.　 It’s important to sort of look at what these devices do specifically, but let me just cut to the chase and say there really doesn’t appear to be much of a hazard in terms of radiation exposure.

There are going to be 2 types of machines, John, that people are really going to see, probably in airports, becoming more common.　 First of all, this is the millimeter wave imaging technology.　 Take a look for that.　 Look for that particular machine and keep this in mind:　 When you go in a machine like this, it’s really using radio waves, John, to create an image.　 So think of this more like an ultrasound rather than an x-ray machine.　 So the amount of energy really given off by something like this is about 10,000 times less than even a cell phone.　

This is another type of machine that you might see.　 Take a look at that type of machine.　 This is using, actually what’s called a back scatter technology.　 These are the types of images that are generated as you can see.　 But, John, what happens here is that you do get some radiation, but it’s really designed to bounce off the skin and then create an image off to the side.　 That’s how they generate those images, That’s how they get these, and they can look for things underneath the skin.　 That’s specifically what they’re trying to do here.　 Both of these should be distinguished from what we’re most familiar with, which is a regular x-ray.　 That’s using ionizing radiation.　 That is penetrating the skin.　 But that is also very different.

But the back scanner, John, the one that is probably going to be the most common, the one that President Obama actually alluded to yesterday as well, it would take about 125,000 trips through a machine like that every year to get to the maximum dose of the safety level.　 So, it seems like they’re pretty safe based on the conversations that we’ve had.

Alright, but you know, these are machines that need to be calibrated, and we all remember several weeks ago you did a story on CT scanners, which are a form of x-ray machine, and some of those machines weren’t calibrated properly and some were giving out multiples of the radiation doses that they should have been giving out.　 So, can we be guaranteed, I mean can we be quite confident, that these machines will be calibrated in such a way that they will be giving out the minimum dose of radiation?

That’s a great question.　 Now, one thing to keep in mind about that study, particularly the one that you’re talking about, CT scanners can give out up to 13 times more radiation, even within the same hospital.　 Technicians within the hospital are allowed to calibrate those machines to try and get better images.　 These machines are all going to be calibrated so that, we’re told by the TSA, at the same level.　 So, you’re not going to be allowed to individually calibrate them at the airport.　 So they should be consistent. At least that’s what we’re hearing now