Following the attempted bombing of North West Airlines Flight 253 on Christmas Day 2009, there has been a discussion regarding the use of full body scanners in airports. These scanners use radio or radiation technology to view below a person's clothing. Their proposed use has sparked a debate spanning science and ethics.

As is often the case in science, there is more than one way to solve the problem of looking below clothing, and understanding each technology's gives and takes is essential. Here we have two options: millimetre and X-ray scanners. Both use parts of the electromagnetic spectrum, the first uses radio waves, and the second uses x-rays.

 

Did You Know?
Millimetre waves have a longer wavelength than the wavelength of light we see and x-rays have a shorter one.

The wavelength is actually an importance difference here! Because millimetre scanners have a longer wavelength the resolution is lower, so small objects may be invisible. Correspondingly, X-ray's short wavelengths have higher resolution and can see smaller objects.

 

Did You Know?
The long wavelengths of communications radio waves allows for the use of radar dishes with holes in them, the small holes are essentially “invisible” to the long waves.

The problem with X-rays is that they are “ionizing radiation” which can cause cancer. Further complicating things, cancer risk from radiation is difficult to gauge and the effects are cumulative and not due to a single dose. This is analogous to sunbathing without sunscreen, once is okay, but chronically and ones cancer risk increases. Experts are concerned that people who are on the verge of getting cancer will be scanned and will, in their own right, become victims of terrorism.

 

Did You Know?
Because their cells are multiplying more often, children are at higher risk of cancer cause by radiation.

Article written by Seth Gilchrist. First published on January 30, 2010.

Seth Gilchrist

I am a PhD candidate at the University of British Columbia in Biomedical Engineering. I obtained my bachelors degree at the University of Wyoming in 2003 and my Masters at the University of British Columbia in 2006. My current research focuses on bone fracture mechanics in hip fractures sustained by osteoporotic individuals. I perform measurements on proximal femurs that are loaded as they would be in a fall inside a high resolution CT machine and also perform video analysis of femurs loaded in a drop tower under physiological loading rates and conditions.


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