For many years, airports have used metal detectors to detect hidden weapons on passengers. This easy-to-use device was safe, but had one serious flaw: it could not detect non-metallic objects that pose a threat. Therefore, screening at airports is now carried out using other technologies.

X-ray scanner

A backscatter X-ray scanner shows a complete image of a person's body. There is debate among experts about the safety of using this scanner.

It is believed that X-ray scanners may be emitting a dangerous dose. “Through this device, a person is exposed to radiation equal to approximately 10% of what he receives during an X-ray chest" says John Sedat, professor of biophysics at the University of California.

Professor of Biophysical Radiology at medical center Columbia University's David Brenner confirms: "There is a very small risk that exposure to X-rays may cause cancer."

European authorities almost immediately after the introduction of the technology banned Europe Bans Airport X-Ray Scanners that U.S. Still Uses. use of X-ray scanners at airports. Then other countries followed suit. However, in some places they are still used.

Microwave scanner

A microwave scanner receives images using radio waves. In this scanner you need to stand without shoes and with your hands raised above your head. Experts say such devices are safe for human health.

Andrew Maidment, assistant professor of radiology at the University of Pennsylvania, explains that devices that emit radio waves only cause harm when they cause molecular changes. The microwave scanner at the airport, fortunately, is not capable of this.

“I was involved in a study that tested the effects of radiation from this scanner on pregnant, potentially pregnant women and newborns. And I can say with confidence that it is safe. I'm not afraid for myself, my wife and children when we go through this scanner,” says Maidment.

Even if you fly on airplanes very often, you receive a tiny dose of radiation that will not harm your health.

X-ray scanners- devices used to obtain fluoroscopic images. These scanners are used in various areas: in the field of safety, in flaw detection, etc. Sometimes X-ray scanners are called medical X-ray machines.

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The first X-ray image was obtained from the hand of V. Roentgen’s wife. The image showed her wedding ring, put on the finger, as well as the bones of the hand. On January 18, 1896, the “X-ray machine” was officially presented by H. Smith; the new machine was presented to the public as a technical miracle and was intended primarily [ ] for fun. Circus performers used these devices to show the public their skeletons and distributed fluoroscopic images of their hands. jewelry on fingers. While many people were fascinated by the discovery of such devices, some were concerned about the possibility of using such devices to see through doors and violate privacy.

In the 1940s and 50s, X-ray scanners were used in stores to help sell shoes (the picture showed how the shoe fit the buyer). Since the discovery of the harmful effects of X-rays, the use of such scanners has almost immediately ceased.

Review

An X-ray scanner usually consists of an X-ray source (accelerator or X-ray tube) and a detection system, which can be in the form of a film (analog technology) or a detector bar or matrix (digital technology).

Baggage scanners

X-ray scanners are used for contactless inspection of cargo and luggage for the possible presence of weapons, drugs and explosives. X-ray radiation is localized inside the scanner body and therefore they are safe for others. The main part of such scanners is an X-ray generator, a detector line for detecting rays passing through inspected luggage, a data processing unit for converting signals received from the detector line into an image, and a conveyor, which is used to carry luggage through the scanner. The resulting images are displayed on a computer terminal, usually located near the scanner.

Doctors are sounding the alarm - after the recent terrorist attacks at airports they want to install X-ray scanners that can cause cancer. There is talk of installing covert search devices even in the Moscow metro. Is it worth refusing to go through the next time you fly on vacation at sea and is it possible to do this?

At the beginning of March 2011, Rospotrebnadzor made an official statement: installations for X-ray scanning of people at airports are dangerous. Chief Sanitary Doctor of the Russian Federation Gennady Onishchenko believes that X-ray scanners can lead to radiation and oncological diseases.

Modern research confirm the fears of doctors. Biochemist and biophysicist at the University of California, San Francisco, David Agard, argues that any dose of X-ray radiation, no matter how miniscule, is harmful. He believes that X-rays cause chromosomal rearrangements that provoke the growth of cancer cells. The installation of such devices at airports will lead to an increase in the incidence of melanoma and breast cancer.

Whoat risk?

X-rays pose the greatest danger to pregnant women. If exposed to radiation in the womb, there is a risk of developing cancer and leukemia in the future. The head of the Center for Radiological Research at Columbia University, David Brenner, adds that 5% of the population is genetically sensitive to radiation. These people have an increased risk of developing basal cell skin cancer.

Separately, it is worth mentioning people who, due to their duties, are forced to constantly be in the air. Pilots and flight attendants undergo X-rays about 400 times a year. These figures for “business travelers”: journalists, businessmen and diplomats are approximately two times lower. Add cosmic radiation, to which passengers are exposed during a flight at a cruising altitude of 10 km. The further a person is from the surface of the planet, the more irradiated he is.

In fact, we can all find ourselves at risk at any moment: complex technology may simply fail, and then any passenger will receive a serious dose of radiation. And a functioning one is a dangerous thing: manufacturers underestimate dangerous indicators in order to obtain a safety certificate.

How it works?

X-ray works on the principle of backscattering, where two extremely weak X-rays are used to create a two-dimensional image on a screen. The Food and Drug Administration (USA) assures that the devices are absolutely safe for all passengers, including the elderly, children and people with implants. According to the Department's specialists, a person needs to go through more than 1000 times a year, and only after that can we say that the radiation exposure standards have been exceeded.

There is a safe alternative to an X-ray scanner - a microwave scanner. The machine directs a beam at the passenger and then analyzes the reflected signal. However, the installation caused many protests. The device allegedly shines through clothing, allowing you to literally “look under your skirt.”

What to do?

At Sheremetyevo and Vnukovo, X-ray scanners are used only for luggage inspection. Passengers pass through rapiscans, whose radiation is 1000 times weaker than radiation mobile phones.

However, you may refuse to pass through any device. Then a security officer will conduct a search in the personal search room. In this case, the passenger will be searched by a woman, and the passenger by a man.

Oleg Polyakov, deputy chief physician of the Russian Medical Academy of Postgraduate Education, comments on the situation: “X-ray is a serious examination. For each patient, his own dose is calculated, taking into account the weight and age of the patient, the location of the organ that needs to be examined. All radiation is recorded, and the annual radiation dose is calculated. It is difficult to imagine what will happen to people who are forced to fly frequently for work. But there are still people with thyroid diseases, oncology, and those who recently had fluorography. Radiation does not go away on its own, it accumulates. If X-ray machines are installed in transport, who will monitor radiation doses for each individual?”

Numbers

• Maximum permissible background for life - 5 mSv per year (millisievert)
• Tooth photo - 1 µSv
• Inspection using the SibScan microdose X-ray system installed at Pulkovo and Domodedovo airports - 0.5 µSv
• Exposure during the flight Moscow - Bangkok - 45 µSv
• Exposure during the flight Moscow - Sharm el-Sheikh - 30 µSv
• Exposure during the flight from Singapore to New York - 90 μSv
• Film fluorography (outdated technology, being replaced by digital) - 500-800 µSv
• Digital fluorography - 60 µSv
• Lethal dose of radiation - slightly less than 1 sievert

Purpose:

IN modern conditions Only the use of electromagnetic metal detectors for human screening and X-ray systems for baggage screening no longer provides the required level of security and control. First of all, this concerns security at airports and customs control at the border, when cold non-metallic weapons, plastic explosives are used to commit terrorist acts, and illegal transportation of drugs in swallowed capsules is carried out.

In addition, the task of increasing the level of security is important:

• on the border with states where armed conflicts are occurring,
• at protected sites,
• VIP persons,
• in mines and enterprises related to the mining and processing of diamonds, precious stones and metals, rare earth elements.

The main problem is that terrorist weapons and items prohibited for transportation can be made of non-metallic materials and can be hidden not only under clothing, but also in natural body cavities. Today, digital human scanning systems based on the use of X-ray radiation are becoming a fundamentally new means of control.

Scanning digital radiography technology for safety:

Unique technology receiving digital projection x-ray image person in full height The “flat beam scanning” method is based on:

• on the use of an ultra-highly sensitive linear array of semiconductor scintillation detectors located vertically as an X-ray receiver;
• on the formation of an extremely narrow (less than 2 mm) monochromatic X-ray beam using a system of collimators and filters with the aim of minimal irradiation of the controlled person;
• on moving a person on a special moving platform located between the collimator and the detector through the X-ray beam, for the purpose of scanning and personal inspection;
• on detecting radiation passed through a person using a linear detector and forming a two-dimensional matrix digital image on the operator's monitor;
• on optimizing the ratio of radiation dose and resolution depending on the specifics of the problem being solved.

A digital X-ray scanner using this technology allows you to obtain a projection image of a controlled person and actually makes it possible to “look inside” the person for the purpose of personal inspection. In this case, there is no obvious ethical problem characteristic of scanning X-ray systems based on reflected radiation, which seem to “undress a person.” In addition, two scans are not required - front, back and in some cases from the side to search a person.

The X-ray scanner is designed to detect dangerous objects:

• from not organic materials hidden under clothing - firearms and bladed weapons, fuses, electronic devices and so on.;
• from organic materials (materials not detected by a metal detector) hidden under clothing - plastic explosives, drugs in containers, firearms and bladed weapons made of ceramics, etc.;
• from materials of any type ingested or hidden in human natural cavities - drugs, explosives, chemical and biological substances in containers, precious stones and metals.

Main Applications:

• at airports, railway and bus stations to ensure the safety of mass passenger transportation;
• at guarded facilities for the purpose of entry/exit control;
• in prisons, as an alternative to strip searching.

Additional applications:

• at the border for the purpose of customs inspection to detect contraband;
• in diamond mines and factories to prevent theft;
• in workshops for finishing and processing diamonds, precious stones and metals, concentrates of rare earth elements in order to prevent theft;
• ensuring VIP security.

Installations:

Currently, SecureScan systems are installed and operated by:

• INCHEON Airport ( South Korea) - 2 systems
• Diamond mines (South Africa, Angola) - 5 systems
• Lodz Prison (Poland) – 1 system
• Los Angeles Prison (USA) - 1 system
• Ensuring VIP security ( Saudi Arabia) - 1 system
• Airport (Türkiye) – 1 system.

Testing of the SecureScan system was carried out at the airports of Orly (France), Amsterdam (Netherlands), UAE, Qatar, etc.

Safety:

Human radiation dose per scan:

• in ultra-low dose mode does not exceed 0.1 μSv;
• in high resolution mode does not exceed 3-5 μSv.

By radiation safety The system meets the American National Standard ANSI/HPS N43.17-2002 “Radiation Safety For Personnel Security Screening Systems Using X-rays.”

Safety for the person being scanned:

By comparison, the typical radiation dose from cosmic radiation for a person on a one-way flight from Malaga to London is 10 μSv, from New York to London 35 μSv, and from Hong Kong to London 50 μSv. Typical background radiation dose received by the average country representative European Union per day is 6-7 μSv.

Thus, the radiation to which a person is exposed to a scanning x-ray system is negligible compared to natural radiation. Exposure to the sun or any flight on an airplane contributes tens of times more to a person’s total exposure to radiation.

According to the recommendations of the American National Council on Radiation Protection (NCRP 1993) and international safety standards for the general population (pregnant women and children among them), an acceptable exposure level of 1 mSv (1000 μSv) per year from all sources of ionizing radiation for non-medical purposes is acceptable. If we take as a basis a value four times smaller - 0.25 mSv, then on this system even pregnant women and children can undergo up to 2500 scans per year without harm to their health, which is obviously unrealistic for reasons of common sense.

When using a scanner at protected sites with a pass (using special cards) access system (for example, in diamond mines and factories), it is not difficult to organize control of the personal accumulated dose. In this case, even when the system is operating in high resolution, total number examinations on the system can be over 300 times a year and examinations throughout the year can be organized in such a way as to prevent the accumulated dose from being exceeded. Objectively, this is quite sufficient to ensure security, taking into account the presence of strict control and a limited number of visits to any protected facility.

Operator safety:

The system can be controlled by one or several operators. If the operator is within working area at a distance of less than 1.5 m from the scanner, its protection at the workplace is ensured using a special protective screen made of lead glass, which allows observation of the person being monitored. The dose received by the operator outside the work area does not exceed the typical background radiation dose, and additional protection X-ray radiation is not required.

Safety for others:

Outside the working area, at a distance of more than 1.5 m from the scanner, the level of X-ray radiation does not exceed the background value and therefore does not pose any danger to others. This allows the scanning system to be placed in a compact area in crowded areas, for example, in airports near the baggage inspection system.

Specifications:

Digital Image Characteristics
Digital Image Size (Scan Fields)	2000x800 mm (ultra-low dose); 2000x800 mm (high resolution)
Image matrix format, pixels	672 x 275 (ultra-low dose); 2688x1100 (high resolution)
Spatial resolution
low contrast objects	5-7 mm (ultra-low dose); 1-2 mm (high resolution)
high contrast objects	0.3 mm (ultra-low dose); 0.2 mm (high resolution)
Scan time	8 sec (ultra-low dose); 16 sec (high resolution)
Average image viewing time	5 (ultra-low dose); 10 (high resolution)
physical characteristics
Dimensions	2100 x 4500 x 2400 mm
Weight	1300 kg
Network requirements	220/110V, 50/60Hz
Power consumption	no more than 6 kW
X-ray generator characteristics:
Operating anode voltage	160 kV
Working anode current	2.5 mA

Airports around the world use X-ray backscatter scanners to screen passengers and baggage. English Backscatter X-ray scanner). This is the same device that at one time caused a number of scandals due to the fact that it “undresses” people.

American homemade product Ben Krasnow assembled current model such a scanner from parts purchased on ebay (author's description). Here's an example of an image Ben captured:

You found out what it is, right?

That's right, it's a turkey in a Christmas sweater:

In addition, she tried to carry an Allen key inside herself, which was easily detected by the scanner.

Principle of operation

Unlike first-generation inspection systems and medical X-ray machines, backscatter scanners record radiation not passing through an object, but reflected from it. X-ray backscattering is due primarily to the Compton effect. While transmission scanners can only obtain the distribution of the density of a substance, backscattering devices can distinguish the composition of a material, including organic material.

The scanner consists of an X-ray tube with a scanning device (in the photo in the middle), an X-ray detector (left) and power supplies (right).

Radiation source

The X-ray source is a tube like this:

It works as follows: electrons emitted by the cathode (right) are accelerated by a strong electric field and fall into the massive anode (left). With sudden braking in the anode material, electrons generate x-rays. Due to the beveled surface of the anode, radiation is reflected to the side and leaves the tube. To power the tube, a high-voltage source of several tens of kilovolts is needed.

The tube is placed in metal case with a narrow exit slot. Opposite the slit there is a collimator disk with small holes, which makes a thin beam from a wide beam of radiation.

During operation of the installation, the disk is rotated by the motor, and the beam moves horizontally, drawing line by line. Vertical scanning is carried out by rotating the tube along with the body and disk around the horizontal axis. For now this is done manually, but the design provides for the installation of a second motor.

Detector

The detector consists of a luminescent screen and a photomultiplier tube (PMT) in an opaque housing.

Under the influence of x-rays scattered by the object, the screen begins to glow. A photomultiplier converts this light into an electrical signal. The signal from the photomultiplier is amplified by a simple amplifier and fed to an oscilloscope, to the brightness control input (Z-input).

The horizontal scan of the oscilloscope is synchronized with the rotation of the collimator, so that one line of the image is visible on the oscilloscope.

The vertical beam deflection device is equipped with a potentiometer, the signal from which is fed to the Y-input of the oscilloscope. Thus, as the X-ray beam is deflected up and down, the line on the oscilloscope screen moves accordingly. To compose a complete picture from individual lines, Ben simply takes a long exposure photograph of the oscilloscope screen.

The image is not very clear and noisy, but the contours of the object and the contrasting elements of the internal structure (for example, a key in a turkey) are clearly visible in it.

Video

Ben talks about his setup and demonstrates it in action:

A story about an X-ray detector and photomultiplier: