Body Scanners: X-Ray Or Not?

Airport body scanners have been a topic of discussion and controversy since their introduction. While they are designed to detect weapons, explosives, and other prohibited items, concerns have been raised about their use of radiation and potential health risks. Some scanners use X-rays, a type of ionizing radiation that can cause cancer and other health issues. However, the amount of radiation emitted by airport X-ray machines is very low and is considered safe by health authorities. On the other hand, millimeter-wave scanners, which are also widely used, do not emit ionizing radiation and are equally effective in detecting threats. While the use of body scanners at airports continues to evolve, with some countries adopting them and others phasing them out, the debate around their safety and privacy implications remains ongoing.

Millimeter wave scanners use non-ionising electromagnetic radiation, similar to mobile phones

Millimeter wave scanners use non-ionising electromagnetic radiation. This means they emit non-ionising radiation, which is a type of electromagnetic radiation that does not have enough energy to remove electrons from atoms. In other words, it cannot alter the structure of biological molecules such as proteins and nucleic acids.

Non-ionising radiation is also emitted by mobile phones and other wireless devices such as radios, Wi-Fi routers, satellites, radars, and pacemakers. It is used to transmit signals carrying information in the form of radio waves. When you make a phone call, your voice is carried on radio waves to the person you are calling.

Millimeter waves are radiofrequency radiation in the gigahertz bands, and they are larger than X-rays. They are also used in radio broadcasting and cell phone transmissions. Millimeter waves are ideal for scanning technologies because they pass through most materials, such as clothing, and reflect off the human body or other objects.

Millimeter wave scanners work by emitting a pulse of energy that travels as a wave to the person standing in the machine. The energy passes through clothing, reflects off the body, and any concealed solid or liquid objects, and then travels back to the machine, which detects the signal and forms an image.

The amount of energy released by millimeter wave scanners is much lower than that emitted by mobile phones. The scanners are considered safe and are not known to pose any health risks to passengers or operators.

X-ray-based scanners use low-dose radiation to detect objects under clothing or in body cavities

X-ray-based scanners emit low-dose ionizing radiation to detect objects under clothing or in body cavities. These scanners are designed to detect weapons, explosives, and other prohibited items, including metallic and non-metallic objects, that may be hidden under clothing or in shoes. They can also detect items in the cavities of the human body, such as drugs carried by drug couriers in the stomach.

The dosage of radiation received from these scanners is typically between 0.05 and 0.25 μSv, which is considerably lower than the radiation exposure from a medical X-ray. For context, a chest X-ray exposes patients to roughly 1,000 times the radiation of an airport scanner. The low dosage of radiation in airport scanners means the health risk is extremely low. According to Dr. Lewis Nelson, a professor and chair of emergency medicine, "It's so tiny that it's inconsequential."

While airport X-ray scanners emit ionizing radiation, which has enough energy to knock electrons away from atoms, the dose is not high enough to cause harm. In fact, the amount of radiation from an airport X-ray scanner is tiny compared to other sources of radiation we encounter daily, such as food, soil, and the air we breathe.

It is important to note that some countries, like Australia, use non-ionizing millimeter-wave technology instead of X-ray backscatter technology for passenger screening. These millimeter-wave scanners use radiofrequency radiation similar to that emitted by mobile phones and are considered safe for use.

Transmission X-ray scanners use higher doses of radiation to detect objects inside the body

Transmission X-ray scanners are used to detect objects inside the body, such as drugs swallowed by drug couriers. They use a higher dose of radiation than other body scanners, but the dose is still very low. The radiation passes through the body and is captured by a detector or array of detectors. This allows objects to be detected that are hidden under clothes or inside body cavities.

The dosage received from a transmission X-ray scanner is usually not higher than 0.25 μSv. This is regulated by the American radiation safety standard for personal search systems using gamma or X-ray radiation. The dosage is also regulated by the ANSI 43.17.2009 standard, which limits the dose on a per-person basis. According to this standard, a person can undergo a maximum of 1000 scans per year.

Transmission X-ray scanners are considered safe and do not pose a health risk. The radiation dose is far lower than that of a medical X-ray. The amount of energy released during the scanning process is also much lower than that emitted by mobile phones.

In addition, airports have safety measures in place to ensure that workers and travellers are not exposed to high levels of radiation. For example, cabinet X-ray systems used to screen luggage have thick walls and lead curtains to prevent radiation from escaping.

While transmission X-ray scanners are considered safe, there has been some debate and concern about their use. Some countries have banned their usage due to safety concerns. Critics have also called the imaging a virtual strip search and suggested that it violates basic human rights and privacy.

Backscatter X-ray scanners use low-energy X-rays to detect objects near the body surface

Backscatter X-ray scanners are used in airports to detect objects near the body surface. They are one of the technologies used for security scanning, alongside metal detectors, millimetre-wave scanners, and cabinet X-ray machines.

Backscatter X-ray technology is an advanced form of X-ray imaging that differs from traditional X-ray machines. Traditional X-ray machines detect hard and soft materials by measuring the variation in X-ray intensity that passes through the target. In contrast, backscatter X-ray detects the radiation reflected from the target. This technology can be used when less-destructive examination is required, and it can operate even if only one side of the target is available for examination.

The use of backscatter X-ray technology in airports has been controversial due to privacy concerns and potential health risks. Some people worry that viewing the image violates confidential medical information. Additionally, backscatter X-ray machines expose individuals to low doses of ionizing radiation, which is considered carcinogenic even in small amounts. However, the doses used in airport scanners are believed to be negligible for an individual. The risk of health effects from backscatter X-ray systems is considered very low, and there are safety measures in place to protect travellers and workers.

In recent years, backscatter X-ray scanners have been replaced in many airports by Advanced Image Technology (AIT) or millimetre-wave scanning devices, which use non-ionizing radiation and are considered safer and less intrusive.

Non-ionising radiation has less energy than ionising radiation and cannot remove electrons from atoms

Non-ionising radiation has insufficient energy to remove electrons from atoms. It is defined as any type of electromagnetic radiation that does not carry enough energy per quantum (photon energy) to ionise atoms or molecules. In other words, non-ionising radiation cannot remove electrons from atoms or molecules. Instead, it can only excite electrons, moving them to a higher energy state.

Non-ionising radiation includes radio waves, microwaves, infrared radiation, and visible light. It is present in technologies such as radio broadcasting, telecommunications, medical imaging, and heat therapy.

In the context of airport security, some countries, such as Australia, use millimetre-wave technology, a form of non-ionising radiation, for body scanners. These machines collect radio waves emitted by or reflected from the body to create a three-dimensional image. This image is generic and does not compromise passengers' privacy, showing no human anatomy. The amount of energy released during this scanning process is much lower than that emitted by mobile phones.

On the other hand, ionising radiation has enough energy to remove electrons from atoms and molecules of materials, including air, water, and living tissue. X-ray machines emit ionising radiation, and about half of the airport body scanners use this technology. However, the dose of ionising radiation emitted by airport X-ray machines is very low and is not considered harmful to human health.

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