Many thermo-plastics, which are made of both organic and inorganic substances (e.g. fruit in a tin) the metal of the tin will be displayed. Where inorganic materials hide organic materials (e.g. The X-ray operator should take into account the shading of the various colours as, obviously, layers of a less dense material will show up as similar to a dense material – for example a box of photocopying paper will appear a very dark orange, in fact almost black. lead crystal) will also appear black, and will mask other material. Very high density materials, such as lead, will show up as black. Items with a mixture of both organic and inorganic materials will show up as green. Explosives may not ALWAYS appear orange if they are masked by inorganic materials – then the colour shown will be a composite of the two materials.ĭenser, inorganic materials such as metals, glass, chinaware will show as green or blue. Explosives are organic materials, so will appear as an orange shadow – the darkness of the shadow will depend on the thickness of the explosive material. Low density organic materials, such as paper, wood, clothing, foodstuffs and plastics will show up as various shades of orange.
Artificial colourisation can assist in identifying certain threats amongst clutter. Artificial colourisation is extremely useful because humans can distinguish thousands of colours, compared to just a few levels of grey. Inorganic (Blue), and 3.Mixed (Green), or coloured with Pseudo Colour which is artificial colourisation of grey levels. The x-ray screener is faced with identifying these silhouettes, artificially coloured to represent any of three main categories of materials: 1. Obtain more accurate results with SIMFOX BAGGAGEĪn X-ray image of a bag may be thought of as an image composed of superimposed and overlapping “shadows” of absorbing materials in the bag, created on a computer screen. That’s why many objects look so different under X-ray to how they look in reality. So a photographic image gives information about an object’s exterior, whereas X-ray supplies information about the composition, density and thickness of an object’s internal structure. The main difference is that the X-ray image is formed as a function of the x-rays’ absorption when passing through material, whereas a photographic image is formed by light reflecting from an object’s surface. An item’s X-ray signature differs in several important respects from an ordinary photographic (optical) image. The term “X-ray Signature” refers to the patterns an item produces on the X-ray machine monitor.
If no X-rays can penetrate an item, because of it extreme density or thickness, it will produce a totally black image (X-ray Opaque). The denser an item is, the darker the image will be. The lower the density of any material, the more transparent the material is to X-rays and the lighter the image will be on security X-ray equipment. Scientists have mapped the atomic structures of all matter, graded the various densities, and display them in what is called the ‘Periodic Table of the Elements’. It is the density (Atomic Weight) and thickness of materials that determine how easily X-rays pass through them. When an item is X-rayed, some of the X-rays pass straight through and some are absorbed and do not come out the other side.
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