Backscatter technology is based on the X-ray Compton scattering effect of X-rays, a form of ionizing radiation. Unlike a traditional X-ray machine, which relies on the transmission of X-rays through the object, backscatter X-ray detects the radiation that reflects from the object and forms an image. The backscatter pattern is dependent on the material property and is good for imaging organic material.
In contrast to millimeter wave scanners, which create a 3D image, backscatter X-ray scanners will typically only create a 2D image. For airport screening, images are taken from both sides of the human body.[6]
Backscatter X-ray was first applied in a commercial low-dose personnel scanning system by Dr. Steven W. Smith.[7][8][9] Smith developed the Secure 1000 whole-body scanner in 1992 and then sold the device and associated patents to Rapiscan Systems, who now manufactures and distributes the device.
The following companies manufacture commercial backscatter X-ray devices that are used in security scanning applications with price ranging from $250,000 to $2,000,000:
Rapiscan Systems, a subsidiary of OSI Systems Inc.[10][11] (device name: Secure 1000)
American Science and Engineering[12] (device name: Smartcheck)
Tek84 Engineering Group LLC, formerly Spectrum San Diego Inc.[13] (device name: AIT84 Body Scanner & Castscope)
Nucsafe Inc.[14] (device name: Backscatter X-Ray RSD System)