An evaluation of airport x-ray backscatter units based on image characteristics
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Little information exists on the performance of x-ray backscatter machines now being deployed through UK, US and other airports. We implement a Monte Carlo simulation using as input what is known about the x-ray spectra used for imaging, device specifications and available images to estimate penetration and exposure to the body from the x-ray beam, and sensitivity to dangerous contraband materials. We show that the body is exposed throughout to the incident x-rays, and that although images can be made at the exposure levels claimed (under 100 nanoGrey per view), detection of contraband can be foiled in these systems. Because front and back views are obtained, low Z materials can only be reliable detected if they are packed outside the sides of the body or with hard edges, while high Z materials are well seen when placed in front or back of the body, but not to the sides. Even if exposure were to be increased significantly, normal anatomy would make a dangerous amount of plastic explosive with tapered edges difficult if not impossible to detect.
KeywordsX-ray imaging Airport security Compton backscatter Explosive detection Personnel screening
The authors are grateful for the valuable input provided by Professor Peter Rez of the Physics Department, Arizona State University.
- Agostinelli S, Allison J, Amako K et al (2003) Geant4—a simulation toolkit. Nuclear instruments and methods in physics research section A: Accelerators, Spectrometers, Detectors and Associated Equipment 506(3):250–303. (http://geant4.cern.ch/)
- Evans RD (1955) The atomic nucleus. McGraw-Hill Book Co., New YorkGoogle Scholar
- Fiejo PV, Hoff G (2008) Geant4 validation on mammography applications. Nuclear Science Symposium Conference Record IEEE 3497–3498Google Scholar
- Guatelli S, Mascialino B, Pia MG, Pokorski W (2006) Geant4 anthropomorphic pantoms. Nuclear Science Symposium Conference Record IEEE 1359–1362Google Scholar
- Kaufman L (2010) Letter to the Editor. Re: airport full body scanners. JACR 7(8):655Google Scholar
- National Council on Radiation Protection and Measurements (2003a) Commentary No 16- Screening of humans for security purposes using ionizing radiation scanning systems. Bethesda, MDGoogle Scholar
- National Council on Radiation Protection and Measurements (2003b) President report on radiation protection advice: screening of humans for security purposes using ionizing radiation scanning systems (SC 01-12,), Bethesda, MDGoogle Scholar
- Operational Requirements Document (2006) Whole body imager aviation applications, USDHS, July, Version 1.9, Final Report. NTIS, Springfield, VAGoogle Scholar
- Rose AA (1971) Vision: human and electronic, Chapter 1. Plenum, New YorkGoogle Scholar