X-Ray Back-Scatter and Junk Pictures



On the previous post, I wrote about the Millimeter wave Scanners in use today at airports.

Now I will write about the other kind of full body scanner, the X-Ray Back-Scatter scanner.

A lot of the previous post was trying to explain about frequencies and wavelengths.

The reason for that was not only to explain what was meant by millimeter, but also to give some explanation about the differences in energy used with the different types of scanners.

As the energy gets higher in frequency and shorter in wavelength, the energy eventually “changes” in the effect that it has on it’s target. This effect is called ionizing and it consists of subatomic particles or electromagnetic waves energetic enough to detach electrons from atoms or molecules.

The molecule with the electron knocked away then becomes something called a “free radical” molecule which is a molecule with an unpaired electron.

These molecules become chemically reactive because of the change in their molecular structure.

The longer wavelength radiation like infrared or light can produce ionizing damage to molecules, but it requires significantly higher flame or “browning” temperatures. As the wavelength gets shorter and shorter, eventually it gets to the point of ALWAYS being ionizing radiation, as in X-Rays and Gamma rays.

Ionizing radiation produces free radicals even at room temperatures and below. Production of such free radicals is the reason these and other ionizing radiations produce quite different types of chemical effects from (low-temperature) heating.

Free radical production is also a primary basis for particular danger to biological systems of relatively small amounts of ionizing radiation that are far smaller than needed to produce significant heating.

Free radicals easily damage DNA, and ionizing radiation may also directly damage DNA by ionizing or breaking DNA molecules.

So getting back to the X-Ray Back-Scatter scanner. The energy that is being used by the scanner, X-Rays, is ALWAYS ionizing radiation and it will ALWAYS produce free radical molecules.

So does the chance of harm outweigh the benefits that it provides? The official term is called “Statistical Collective Risk”.

Of course, if there are no benefits at all then it will always be a bad choice.

Ideally, there would be no risk at all but in real life everything has risk.

For example, society would have a hard time existing without automobiles but people die everyday while using them. The benefit has been determined to be greater than the risk.

Risk is made even smaller with seat belts, air bags,etc.

Something seemingly benign as a toothbrush has probably killed a few people. Aspirin also probably has taken a few lives.

But again, the benefits have been determined to outweigh the risks.

So what benefits does the X-Ray scanner give? X-Rays are particularly good at contrasting certain materials. Organic matter, like your body, is made of relatively low Z matter like carbon, oxygen, hydrogen, and nitrogen.

This strongly reflects the X-rays, yielding a brighter image. High Z materials, like most metals, will reflect poorly, so they will show up as dark splotches.

So the possibility of catching dense plastics,metals, and explosives on a person boarding an airplane may be better, thus providing additional benefits of increased protection and saving lives.

But would they have caught some of the attempts that terrorist have already made with explosives?

Terrorist can be quite creative in the materials and locations of where they put their tools of destruction. Will they just adapt to the new rules of the game to achieve their goals?

The energy strength of the X-Rays will determine the amount of free radical molecules generated. With free radicals molecules, the risk that some of those will generate cancerous cells will be automatic.

That risk may be say…1 cancer occurrence in 1 million people.

More scans equals more molecules equals more chances of those molecules causing cancer. So the risk becomes greater, maybe 1 cancer occurrence in 100,000. Again, it is a benefit/risk assessment.

*** What is my opinion?? (not necessarily that of MMA)



I always like to read articles that have all the technical jargon but sometimes not so much on trying to “read between the lines” of what the author thinks. Nice to have something that cuts to the chase, so to speak, at the end. And that is what I am going to do here.

So…what is my opinion of the full body scanners?

Both types are way too intrusive and violate privacy and personal dignity. But polls indicate that the majority of the population are willing to put up with this to insure safety with airline travel.

The Millimeter Wave scanner could be improved quite a bit so that it DOESN’T have to show all the nudity.

But the public relations was handled so poorly, will the public ever think anything else but those strange pictures of nude people when scanners are mentioned? It seems to be relatively safe as far as the energy concerns but some new study may show information that proves other wise.

Fix the pictures to display stick figures like Germany has already done, use pattern recognition, and this may be a valid tool that the public will increasingly accept.

The X-Ray Back-Scatter scanner in my personal opinion should NOT be on the first line of defense. Use that machine only when preliminary indications show that the passenger is to be suspect. There is no doubt that X-Rays have some risk.

Is the risk so small that it’s acceptable?

Perhaps, but the 1 person that gets cancer may think otherwise. These machines excel at baggage and cargo scans. Keep them in that area of expertise.