Sydney airport has just begun using 3D body computed tomography scanners in its Qantas domestic terminal, T3. Though CT scanners have been widely used in international terminals in Australia for several years, and are in place in Melbourne’s T4 terminal and at Gladstone and Canberra airports, it is the first time many passengers have seen the technology at a domestic airport.
They are large tubes that passengers are asked to enter, before raising their arms while the machine rotates around them. They use nonionising millimetre-wave imaging to scan a person, looking for anything they may be carrying under their clothing. They are capable of detecting metallic and non-metallic items.
Airport security staff are presented with a generic cartoon outline of a person, with areas of interest highlighted in square boxes. Melbourne airport says no individual scans or personal information is stored or transmitted by the scanners.
CT scanners are also used for carry-on luggage.
In 2018 the then home affairs minister, Peter Dutton, announced that airports would be required to shift from using metal detectors, with budget funding earmarked for regional airports.
This came the year after two brothers plotted to blow up a passenger plane with a bomb hidden in a meat grinder.
“We’re worried about different devices going through the scanner that wouldn’t be picked up at the moment,” Dutton told the Melbourne radio station 3AW in 2018. “We’re worried about gels. We’re worried about noxious gases, all sorts of things which potentially don’t get picked up.”
Dutton said the new scanners would be rolled out “over the next couple of years” but it has taken four years for one checkpoint in one terminal of Australia’s busiest domestic airport to get the technology.
Guardian Australia understands the other checkpoints in T3 in Sydney will be upgraded with the same technology by the end of the year.
The Australian Airports Association estimates the cost of the upgrade is $2bn. In a pre-budget submission this year, it said the size, scope and scale of the upgrade, along with the pandemic’s effect on the airline industry, had made the project more complex for the 10 largest airports in Australia, and called for federal government funding to offset the cost.
In theory, yes. CT scanning means passengers will no longer have to remove laptops, aerosols and other items from their carry-on luggage at security checkpoints. But they will still need to remove jackets and other outerwear.
Last week the ABC reporter Louise Milligan tweeted her experience of being required to remove a fitted jacket and said others had complained about security “heavy-handedness”.
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Sydney airport declined to comment but the security contractor, Certis Security, told Guardian Australia the removal of coats and jackets was a requirement and referred inquiries to the regulator, the Cyber and Infrastructure Security Centre.
In practice, delays are still likely at airports given ongoing staffing shortages, so the scanners are not likely to shave off any time for quite a while.
Though exceptions are made for people who have medical or physical conditions that prevent them from going through body scanners, airports will refuse to let you enter the terminal if you do not comply.
Introduction
Security screening at airports has been common practice for many years, but has recently undergone significant changes.
The latest technologies for airport security screening are whole-body imaging machines. These machines operate by scanning X-ray (ionising radiation) or extremely high frequency radiofrequency (RF) radiation (non‑ionising radiation) over the passenger's form.
These low output X-ray whole-body scanners or millimetre wave scanners provide alternatives to the traditional pat-down method of body searching and extend the detection capabilities of existing technologies. The machines are designed to detect weapons, explosives and other prohibited items concealed under clothing. Some of these technologies can also detect explosives that can be carried by passengers onto civil aircraft in a liquid, aerosol or gel form. These technologies are already in use in Australia, the United States, Canada and Europe.
The millimetre wave scanners are now the most common system deployed in airports around the world and are the only types used in Australian international gateway airports.
Millimetre wave technologies
Millimetre wave scanners use non-ionising radiation. Millimetre waves are radiofrequency radiation in the gigahertz bands, similar to that emitted by mobile phones. Clothing and other organic materials appear translucent to radiation of this type. These machines collect radio waves emitted by or reflected from the body to create a three-dimensional image.
These scanners are available in both active and passive forms. Active scanners transmit very low intensity millimetre waves from one or more antennas as they are rotated about the person being scanned. The reflected waves are then measured and reconstructed into a 3D image which is displayed to operators in a generic format that does not compromise passengers’ privacy and shows no human anatomy. A passive scanner collects the millimetre waves emitted by any warm object such as a human body, and does not transmit any radiofrequency radiation onto the person being scanned. In both cases, objects beneath clothing will be displayed in sharp contrast to the body being scanned.
These scanners do not pose a health risk to passengers or operators and there are no known safety concerns to people with active implantable medical devices, such as pacemakers, as the amount of energy released during the scanning process for body scanners are much lower than that emitted from mobile phones.
X-ray backscatter technology
Backscatter X-ray (also known as Z Backscatter) technologies measures the X-rays that are backscattered from the object, in this case a person being screened.
The amount of radiation received during a scan is very low, particularly with some of the current generation of backscatter scanners. The dose received in one scan is 200 to 1000 times less than the amount received during a chest X-ray.
The radiation risk resulting from the use of backscatter scanners is very small, even for children or pregnant women. The ionising radiation from backscatter scanners is in the form of low energy X-rays, which will deposit most of their energy in the skin and underlying tissue. Considering the low radiation doses delivered by these machines, the resultant increase in the incidence of skin cancers within the population of scanned individuals from the use of backscatter scanners will be extremely low.
Given the current security challenges of the world, there are physical checkpoints, baggage scanners, and metal detectors in many public spaces. It is therefore not surprising that at airports, one of the busiest hubs for transportation, security is getting tighter increasingly. The security process is designed to protect us, the passengers, though most times this process could be quite invasive. However, the question frequently arises as to what exactly can be detected by these scanners we see at airports?
Airport scanners can detect metallic and non- metallic objects on the body, including drugs and gold, hidden under the clothes and in baggage. Still, most times, they cannot detect the exact material, but provide visual cues about the material of the object, in the form of different colors.
Airport scanners are specifically designed to detect non-metallic items on people’s bodies that may escape the metal detectors. The scanners can see anything on the body, under the clothes but cannot see inside the body.
In fact, on countless occasions, things like hair extensions, bobby pins in the hair, use of underwire bras have gotten people flagged. Hence, it is often advised to keep one’s clothing completely free from any external item that could trigger the scanners.
With that said, before we look at what an airport scanner can detect, we have to understand the basics of how they work!
How Do Airport Scanners Work?
Airport scanners work based on the X-ray radiation — a high-energy electromagnetic radiation. X-rays in simple terms are a beam of high energy “light”. The beam is blocked (attenuated) by every material substance to some degree and comparisons are made between the level to which two or more substances block this beam.
The typical modern airport scanner uses two detectors. When baggage is passed through a scanner at the airport and the X-rays hit the first detector, the energy and position of the content is recorded.
The first detector collects only low-energy X-rays while the second detector collects only high energy X-rays.
The machine then compares the outputs from both detectors to construct an image showing the position of the objects, a likelihood of the material from which the objects are made, and their density.
- Metals and glass are indicated with the color blue or green.
- Organic materials like drugs, paper, food, and explosives are marked with orange color.
- The denser objects are marked by darker colors.
What Can an Airport Scanner Detect?
There is no such material that would deflect X-rays around it, rendering it completely transparent to the rays and therefore invisible to the X-ray scanner. However, high-density materials like Osmium, Iridium, Platinum, Rhenium, Gold, Tungsten, and Lead are difficult to see through.
For example, lead appears as a bulky white opaque image on the X-ray scanner and whatever object kept inside it cannot be detected by the X-ray scanner.
Let us briefly consider if gold and drugs can be detected by an airport scanner:
Can Airport Scanners Detect Gold?
While airport scanners cannot determine an object’s exact composition, they can tell if an object is organic or metallic (or low density or high density). Therefore, airport scanners can easily “detect” gold but cannot differentiate it clearly from another dense object like tungsten or platinum.
The inspector is trained to watch out for precious stones like gold and diamond. His suspicion is raised when the scanner displays an image seemingly showing gold, or another similarly dense objects. The passenger is then called aside for further inspection of his luggage and questioning.
So, airport scanners cannot distinctively identify gold but they can detect dense, radiation stopper objects like gold.
Can Airport Scanners Detect Drugs?
The X-ray intensity and color that’s left after transmission through a sample can be used to detect illegal drugs and explosives. There is a database of all acceptable colors, the relevant authorities and security agents are alerted if the output of the scanning does not match any of these acceptable colors.
A trace portal machine, commonly known as a puffer machine is also used at airports to detect illegal drugs and explosives.
Well-trained dogs also do a fantastic job in the sniffing out of certain scents associated with illegal drugs. The most current and amazing development in security is the training of honeybees.
Can you believe that?! Honeybees would be used in the nearest future in collaboration with advanced video computer software in the detection of contrabands at airports and other public infrastructures.
Categories of Airport Scanners
The machine scanners used for airport security purposes can be broadly categorized into a few categories. They are:
- baggage scanners
- full-body scanners (millimetre wave and backscatter scanners)
Baggage Scanners
Baggage scanner machines use radiations from X-rays to see through the surface of luggage to obtain explicit images of the items inside the luggage.
X-rays sent from one side of the machine are recovered on the opposite side by another pair of detectors. The potential baggage to be scanned goes through the lead-lined curtains, which absorbs some of the energy as it crosses the X-rays path.
This means that the absorbed X-rays have less energy than those that were reflected. From this information, the inspection officers can calculate the density of each object, which informs whatever appropriate actions to be taken.
Body Scanners
Full-body scanners can detect metallic and non-metallic objects on the exterior of the body. Unlike the medical diagnostic X-rays, full-body scanners can neither see inside the body nor diagnose disease.
New Advanced Image Technology (AIT) scanners have been designed to protect passengers’ privacy by showing only a generic outline, which cannot reveal gender or body type.
There are two kinds of full-body scanners used at most airports namely the Millimeter-wave scanner and the backscatter X-ray scanner.
millimeter-wave Scanners
Millimeter wave scanners employ millimeter wave imaging technology to bounce electromagnetic waves off the traveler to provide an animated image like a paper doll to detect where potential threats are located.
Millimeter wave scanners have been in use in many airports since May 2013. The scanner processes an image by using colors to mark out any areas that may require further screening.
However, when a green “GO” sign like the traffic light appears on the screen without an outline or box, it means the passenger is cleared to proceed.
Millimetre wave scanners provide an alternative for people who are averse to pat-downs. Millimetre wave scanners only detect what is worn on the body and hidden under clothing.
Backscatter X-ray Scanners
The Rapiscan “backscatter” screening machines were in use before the Advanced Imaging Technology (AIT) scanners. The backscatter X-ray machine scans the body using ionizing radiation or X-rays deflected by the human body. However, the backscatter showed too many intimate details of the body allowing inspectors to see people virtually naked.
Backscatter machines have now been sacked in most airports of the world because of these explicit images and replaced with AIT scanners (millimetre wave scanners).
However, in major US, UK, and European airports where they remain in use, the officer viewing the image is in a separate area where they do not make direct contact with the scanned passenger. Backscatter scanners can detect both metallic and non-metallic objects, ranging from guns to foods, drugs, plastics, and so on.
According to JAMA Dermatology, it has been found that some items that pose no security threats are flagged by new airport body scanners that use radio frequencies. Including rare cases where the scanner’s alarm is set off by protrusions on the passenger’s body.
The major difference between the backscatter X-ray scanner and the millimeter wave scanner is that the former requires two pictures to be taken – a frontal and a rear picture. While millimeter wave scanners produce a single image and emit far less energy making them a lot safer.
Can You Hide Things from an Airport Scanner?
The principle of X-ray examination is based on the varying atomic composition of different materials. It explains why different atoms reflect or absorb X-rays differently. The intensity or exposure time of the X-ray radiation can be increased or a physical inspection carried out if the image of the content of the container is not clearly visible.
Therefore, to hide things from an airport scanner, the trick is to conceal the true identity of an object. For example, semi-liquid explosives could be put into toothpaste tubes and shampoo bottles, which is why from experience, inspection officials restrict such items from carry-on bags.
Electrical contraband items could also be hidden in power plug adapters as long as the voltage falls within the 110V/220V of laptop power supplies.
In most cases, X-rays pass easiest through light atoms (hydrogen, oxygen, nitrogen, carbon), and with more difficulty through heavier atoms like (sulfur, iron, nickel, lead, gold, mercury, etc). Certain people use this information and try to disguise items like diamonds (carbon) by mixing them with a pack of scorched almonds or (carbon material).
Very dense materials normally block X-rays efficiently. Lead and tungsten are frequently used for hiding materials.
But of course, the suspicion of the agent is raised when a scanner detects this dense object in the luggage. Though it cannot see the contents, such passengers would be pulled aside for “extra screening”. A chunk of lead in a piece of luggage shows the passenger most likely has an ulterior motive and this may not end well in his favor. Wrapping anything in lead or tungsten foil would simply ensure it’s confiscated.
It is a very difficult and dangerous task to try to hide things from an airport scanner. But if somehow the scanning machines are outsmarted, the well-trained security dogs and the intelligent, experienced security officers still have to be contended against.
Terahertz scanners
Some airports even have Terahertz scanners. The latest Terahertz scanners can scan the body – often covertly, and can detect anything hidden – from paper crumps, dollar bills, microSIM cards, to drugs and ceramic weapons.
Though sometimes, human negligence or oversight may allow for lapses in the security checks as most of the inspection agents are mostly looking out for large quantities of smuggled cocaine and weapons rather than few drugs for personal use.
Unfortunately, some take their criminality several notches higher and become human couriers for smuggling illegal drugs. The digestive tract is opened up and a large amount of drugs is stored. There are horrible cases where the ingested balloons of drugs burst inside them and unceremoniously led them to an early grave.
Listed below are some items people have attempted to hide contrabands from airport scanners over time:
Aluminum
Aluminum foil is almost invisible to X-ray except that its line of folds might initiate figurative noise that will lead to further inspection by the officials.
Aluminum has the ability to refract and slow X-ray. Therefore, the power of the generated X-ray radiation must be sufficient enough to generate an improved image by penetrating the thickness of aluminum as it cannot absorb high energy rays.
Carbon
Carbon is so transparent that it is difficult to see the carbon paper as an X-ray image unless the X-rays are soft and a film is used instead of a solid-state camera.
X-ray penetration is related to atomic number – the lower the atomic number the more penetrable it is. Carbon’s atomic number is 6, and it is easily penetrated.
It could, however, be adjusted to cast a very faint shadow on the image. The image would be cleared when the X-ray beam is tuned to a lower penetrating power. Carbon paper is terrible for hiding things because it would be translucent enough to reveal its content.
Leafy Substances Like Marijuana
If marijuana flowers were hidden in a box, it would be easily detected because the content is homogenous, since there is nothing to disrupt visual contrast or confuse mental clarity.
On the other hand, if a small amount of marijuana were hidden in the socks of a suitcase loaded with several other items, it would be difficult to detect because the image is “busy” as a result of the varying densities of papers, food items, clothing, plastics bits, legitimate drugs and so on.
However, if a large amount of marijuana were attempted, then an alarm may be raised because of the unusual packaging. Then always remember there would be sniffing dogs too.
Conclusion
It is clear that the airport security system is not near perfect yet. However, there is significant ongoing improvement in airport security screening. From physical frisking to X-ray baggage scanners, full-body scanners, and electromagnetic metal detectors.
It can only get better as there are innovations on the way ready to improve security screening to guarantee safety without violating human modesty!