3D images with new technology

The development of technology has made images sharper and the scanning process via airport x-ray machines smoother. Images can be modified to get a better view of the contents of the scanned baggage. At Helsinki Airport, for example, so-called dual view machines are used that produce two different images of one scanned item. What this means in practice is that we seldom have to re-scan baggage, which makes screening flow more smoothly. New scanners have been ordered for Helsinki Airport’s baggage handling centre. With a combination of X-rays and CT technology, or computer tomography, these scanners will automatically detect explosives. In CT scanning, the source of radiation rotates around the scanned item at a high speed, and a three-dimensional image can be produced. One new machine can scan up to 1,800 bags per hour.

Organic matter, such as wood, water, plastic and textiles, are coloured orange. Inorganic matter, such as metals, show up as blue. If organic and inorganic substances overlap in the scanned item, it appears green on the screen. For example, tennis balls in a metal tube look green. Other substances that are shown in green include salt, glass and bones. The denser the substance or the thicker the layer of substance on the X-rays’ way, the darker the item appears on the computer screen. Substances which are too dense for the radiation to run through appear black. The scanner that people now pass through uses terahertz radiation which is different from x-rays. It has low penetrating power and therefore only goes through clothes and a little bit of skin. There is some dose to the skin but it is very small.

Medical x-ray machines and airport x-ray machines utilize the same principle. But in the medical field, x-rays are used to get very minute details of the human anatomy. We can see trabeculae on our bones with an x-ray. This is pretty impressive. The airport uses a very low amount of x-rays, just enough to penetrate your body and show your silhouette. The whole point is to see if you are hiding anything on yourself. Since it is so low powered, it cannot penetrate even a lot of clothes which is why you get patted down if they suspect the absorption of x-rays in that particular area of the body is higher than expected. They won’t see if you have a fracture in an ear port. However, they will see if you have C-4 on you or a napkin in your pocket.