When, some time ago, X-ray body scanners were introduced at the airport for security reasons, the inevitable controversy arose between those who said there was nothing to worry about and those who feared their effects.
The question then subsided just as it had raised or in any case had passed into the background, because after all everyone likes to feel safe and patient if when you go on vacation you have to go through a scanner for a few seconds. There are so many things that make us much worse, we know that. But what about those who travels often?
It is a question that researchers have also asked themselves.
Although the radiation dose is very low and therefore the risk of tumors practically nil, we must consider that those who work in airports or often travel for work must multiply this quantity and reach levels if not on guard at least a little more alarming. Scientists are pessimistic, despite the assurances that come from many quarters about practically no risks. Who to believe?
But what are these body scanners and how do they work?
There are mainly two types of scanners: millimeter-wave scanners, which use high-frequency radio waves, or X-ray backscatter scanners, which use low-energy X-rays.
The first type is based on the fact that clothes and other organic materials are transparent to a particular frequency of radio waves, in the order of the teraherz (THz, from which the name T-rays). These waves, emitted simultaneously by two rotating antennas around the body, then penetrate into the first layer of clothing and are reflected by human flesh, thus returning a complete body image.
Scattered X-ray scanners work differently. Unlike normal X-ray scan systems, which measure the difference of hard and soft material based on the different transmission of rays in the material, these scanners measure the reflection of X-rays.
Based on the Compton effect, these scanners need less energy X-rays than those used for X-rays. As in the case of millimeter-wave scanners, electromagnetic radiation passes through clothes, and is reflected by the human body. This technology, however, allows a reconstruction of the body with an image in 2 dimensions, and not 3 as the other. For this reason, in airports using this system it is necessary to perform two scans of the individual, one frontal and one from behind.
In addition to the practical difficulties (additional queues for security checks), the inclusion of this type of check poses two main problems: the aspect linked to individual privacy and the problems of dangerousness of these electromagnetic emissions.
As for the privacy concern the images obtained with these scanners, especially those with millimeter waves, are extremely detailed and, without having to work too much in photoshop, one can easily obtain photographs with realistic colors of the naked body of the observed person.
The other issue is related to the health of passengers, especially the so-called “frequent flyers”. In fact, exposure to electromagnetic radiation can have consequences for humans. The American College of Radiology (ACR) immediately hastened to declare that the X-ray dose received by these scanners is decidedly lower than that to which it is subjected every day by natural radiation.
Similarly, high-frequency radio radiation produced by millimeter-wave scanners is equivalent to a phone call made from a cell phone for a few minutes. The energies and intensities involved are very low, and are therefore harmless for the passenger. There are some points, however, that still leave some perplexed.
First of all, infants and young children are more sensitive to electromagnetic radiation produced, for example, by mobile phones, and therefore also by these scanners. Furthermore it is sufficient that the calibration of the machine is slightly different from the standards, so that things change.
In fact, although radio waves in the teraherz range are not sufficiently energetic to break the DNA chain, studies have shown that, in some cases, non-linear resonance can occur, which can flake the double helix structure of DNA . This situation is undoubtedly remote, and the likelihood of this happening is not a risk, but what some researchers wonder is whether the game is worth the risk.
Whether the risk is high or low, it is somehow decided to undergo an extra radiation, compared to those that surround us every day. Not to mention the annoyance that can be felt in knowing oneself naked in front of strangers.
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