Airport Passenger Screening Using Backscatter X-Ray Machines Compliance with Standards (2015) / Chapter Skim
Currently Skimming:
3 X-Ray Backscatter Advanced Imaging Technology
3 X-Ray Backscatter Advanced Imaging Technology
Pages 33-39
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 33... ...
Smith in 1991.1 In summary, a well-collimated pencil-beam of X rays is raster scanned across an area in which a person is positioned, and the X rays backscattered from a person toward the source are collected by large area detectors adjacent to and on the side of the X-ray source. The spatial resolution of the X-ray backscattered image is defined by the source collimator aperture and distance from the person to the source; the resolution is not defined by the detector.
|
From page 34... ...
The person being screened using a dual-pose AIT system is not subjected to twice the X-ray dose compared to the single-pose AIT system; they are receiving approximately half the X-ray dose for each of the poses for a total dose equivalent to that from the single-pose AIT system. The actual anterior and posterior doses are given in Chapter 7.
|
From page 35... ...
allows the pencil beam to cover a large area and thus generate a two-dimensional X-ray backscattered image. The slit aperture (bottom left)
|
From page 36... ...
This re sults in a single horizontal line image of the X rays backscattered from the person.3 The entire housing of the X-ray source, fan-beam collimator, and chopper wheel assembly is vertically translated during the scan so that successive horizontal image lines are displaced to form a two-dimensional image. Because the total vertical travel of the X-ray head is less than the desired scan height, the tube and collimator assembly also rotate about the horizontal axis.
|
From page 37... ...
The fundamental X-ray generation for SmartCheck is similar to the Rapiscan design in that AS&E's new AIT system employs a tungsten anode X-ray tube that operates at a voltage of 50 kV. They differ in that the AS&E's X-ray tube current is 12 mA, while Rapiscan's is 5 mA, and AS&E's AIT system generates its raster scanning pencil beam of X-rays by collimating the X-ray cone-beam emitted by the source using a vertical hollow cylinder surrounding the X-ray tube and rotating about its central axis.
|
From page 38... ...
A dual-pose model requires time for the person being screened to turn for the second scan. As with the Rapiscan, persons being screened using a dual-pose AIT system are not being subjected to twice the X-ray dose compared to the single-pose AIT system; they are receiving approxi mately half the X-ray dose for each of the single poses for a total dose equivalent to that from the single-pose AIT system.
|
From page 39... ...
X - R a y B a ck s c a t t er A dv a nced I m a g in g T ec h no l o g y 39 FIGURE 3.4 Composite images, including both transmission and backscatter image data are shown. SOURCE: Scanned images from the AIT84 security scanner, provided by Tek84 Engineering Group, LLC.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.