Body and baggage scanners are used for security purposes in places such as airports etc. These scanners scan the human body without removing clothes thus increasing efficiency of security checks. The scanners can detect the presence of any dangerous and lethal equipment.
Backscatter radiation is the radiation that is reflected (scattered) from a material back towards the X-ray radiation source.X-ray security units using backscatter radiation operate by exposing the subject to low energy X-radiation. This low energy radiation passes through clothing but is readily scattered by dense objects. Some of the radiation is scattered back into a series of radiation detectors, and creates an image of the subject’s body, showing any items concealed under the clothing.
Backscatter X-ray systems use a narrow, pencil shaped beam that scans the subject at high speed in a horizontal and vertical direction. Large detectors are installed on the same side of the subject as the X-ray source. The person stands in front of the enclosure and is scanned by the X-ray beam, which has a typical cross-sectional area of approx. 25 mm2. Usually the person is scanned twice, once from the front and then from the back. Sometimes lateral scans are also performed.
Transmission radiation is the radiation that passes directly through the person being examined. This radiation can be measured by a detection system placed on the side of the person opposite to the X-ray source.Transmission X-ray security units use significantly higher X-ray energies than backscatter units to create a radiographic image of the subject. The image is similar to those used for medical purposes and shows the skeletal structure of the subject, on which can be seen any contraband items, with sufficient X-ray absorption contrast, which the subject has swallowed as well as any weapons hidden on the body beneath the clothing.
Transmission X-ray systems generally use a vertical fan-shaped beam of X-rays and a linear array of detectors. The person stands between the X-ray tube and the detector array and is scanned by an X-ray beam having a typical width of approx. 2 mm. The limiting quantity for the spatial resolution is the size of the detector elements.
created with
