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22/10/2014

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Security and fullbody scans

By Wendy Barnaby
 
What a pity the school children didn’t show up.  The predominantly middle-aged audience for Tim Drysdale’s lecture voted, when asked to choose from a wish-list of five superpowers, to be able to fly.  They didn’t vote for X-ray vision, which was one of the other options.  They were probably only too aware of what X-ray vision – or the popular version of it – would reveal.
 
After all, the subject of the lecture was “The ethics and technology of seeing through clothes”.
 
Not that we were left in ignorance for long.  It’s not X-rays which zap travellers at airports:  that’d be too dangerous.  No, it’s radiation at about 100 gigahertz.  Millimetre waves, to you and me.  Directed at a passenger, they penetrate the clothes, and whatever may be concealed under them, and bounce off the skin.  What is reflected back is analysed to reveal all.
 
“All” means non-human objects, which tend to show up as bright patches with straight edges.  Think of a knife or a gun or a pouch of plastic explosives.  They can be made of metal, ceramic or plastic:  still, they’ll show up.
 
These scanning devices are currently in use in Edinburgh and Glasgow airports. They’re useful because they’re quick.  You step into a booth and turn around in front of the scanner, which alerts an operator to anything suspicious.   Airports only allow ten seconds for scanning each passenger.  This all-seeing eye will also reveal CDs and DVDs, so some companies use them for checking that employees aren’t stealing data.
 
Millimetre waves give no dose of ionising radiation. X-rays used so that they reflect from the body, instead of passing through it as in medical applications, are also used in some scanners.  Called backscatter scanners, they do give a dose of ionising radiation, but it’s very small:  you’d need 50 scans to collect the radiation you get from one dental X-ray.  But this sort of scanner also produces sharper pictures.  They’ve been described as resulting in “photo-quality images of what's going on beneath our clothes".
 
And that’s the problem with these scanners.  Who wants to have their figure revealed?  Probably-apocryphal rumours whisper that some celebrities’ fullbody scans have been printed off and circulated to airport staff who have nothing better to do than leer over celebrities’ fullbody scans.  But you don’t have to be a celebrity to feel that either sort of scan might invade your privacy.
 
Various measures are possible to allow us to keep our modesty intact.  The operator who sees you may not see the scan.  The operator who checks the scan may not see you.  Images should be deleted if they give no cause for concern.  Human error on all counts is always possible.  Drysdale, who was giving the annual Isambard Kingdom Brunel Award Lecture, came across as an enthusiast for these technologies.  He thought there should be a move towards automated analysis.
 
Towards the end of the lecture, he asked the audience whether they were happy with the health risks of an X-ray backscatter scanner (most of us were), and later, if we thought body scanning makes flights safer.  Again, most of us thought they did. Had the children been there, Dr Drysdale would have been pleased with them, too, for giving the right answers.

 

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