Airport screeners scan for marijuana

Radiation exposure from body scanners at the airport

With the introduction of the new X-ray body scanners at airports, many passengers and experts are wondering how safe these devices are in terms of radiation protection. Travelers and flight personnel fear not only damage to their health, but also the violation of personal and data protection rights. There are currently over 400 full-body scanners in use at approximately 80 airports in the United States. At the 25th European Radiology Congress in the Austria Center in Vienna, specialists from the field of medical imaging will discuss the latest research findings on this topic.

Body scanners that work with X-rays are used at airports to detect suspicious objects that are worn or hidden by passengers directly on their bodies. The technology used here is the same, based on ionizing radiation, as used in medicine and science.

This type of radiation is classified by the World Health Organization (WHO) as a carcinogenic, i.e. carcinogenic, substance. However, it must be mentioned here that the risk associated with this is closely related to the strength of the radiation exposure, which is very low in the case of body scanners.

“The effective radiation dose to which passengers are exposed during one of these scans is around 0.05-0.1 mSV, which in turn corresponds approximately to the radiation exposure that one is exposed to during a two-minute flight in an aircraft at cruising altitude. Just so that you can put this in perspective, one hour of flight time represents a load of 40-80 scans, a chest X-ray 1,000-2,000 scans and a CT even 50,000-100,000 scans ”, says Prof. Vock, expert for radiation protection from University Hospital Bern.

Further comparative values: a medical X-ray examination of the chest corresponds to the radiation dose of around 1000 airport scans, with a mammogram it would be 4000, with a CT of the abdomen and pelvis even 200,000 scans. The radiation load caused by the controls is therefore out of proportion to the dose that occurs during the flight at high altitude.

Researchers calculate in the journal “Archives of Internal Medicine” that the detectors cause around six cancers in the course of their life in 100 million passengers who make 750 million flights a year.

However, these six diseases would have to be viewed in the context of the 40 million cancer cases that would occur in a lifetime. Nevertheless, the biological influence of such low doses is not known, whether it is negligible would have to be clarified by further studies, added Prof. Vock.

Risks and benefits need to be weighed

However, if you look at the linear no-threshold model (LNT), an internationally recognized standard system for radiation exposure, it emerges from this that stochastic amounts of radiation are proportional to the respective dose without a lower limit and thus remain a residual risk even with the smallest amount. However, there is still no evidence to what extent this model is applicable to the amount of radiation that is used in body scanners.

If you look at this according to the ALARA principle (As Low As Reasonably Achievable), which represents the principle of radiation protection, the risks and benefits must always be weighed first in order to recognize whether the respective radiation exposure is accepted or not, says Prof. Vock.

“The amount of radiation that is used by the body scanners is very suitable for tracking down strange objects such as weapons that are hidden on the surface of the body. The method is far less suitable for displaying objects that are hidden in body cavities or, in some cases, can even be completely overlooked. Due to this rather low benefit, the discussions about the amount of radiation and the concerns about scanning small children and pregnant women can also be explained.

In the meantime, after a test phase of three years, the EU has banned these scanners again, and devices based on microwaves are now to be used, ”says Prof. Vock, who is not convinced of the benefits of conventional body scanners.

Naked scanner: passengers complain about loss of privacy

Many passengers, however, are much more concerned about the loss of their privacy than about the radiation dose. Body scanners are able to create detailed images of the body's surface and so it has always been assumed that “nude images” are also created here.

In order to prevent misuse, there is no visual contact between the passengers and the airport employees evaluating the data, the images are not saved, filters are installed that hide recognizable body details and the evaluation is often done entirely by computer programs. However, these fears and the long scanning time convinced those responsible in the USA to switch from X-ray scanners to those that work on the basis of microwaves.

Although the old devices are still in use at less frequented airports, passengers here have the option of subjecting themselves to a conventional security check using metal detectors and scanning.

¹ European Society of Radiology

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