X-ray Backscatter Detectors
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X-ray Backscatter Detectors By Mark Guseman
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X-ray Backscatter Detectors. By Mark Guseman. Topics. Source of x-rays Interaction with matter Detection and Processing Fooling the Detector Health Concerns. Source: Towe and Jacobs 1981. Source of X-Rays. Two guns used in airport detectors - PowerPoint PPT Presentation
Transcript of X-ray Backscatter Detectors
X-ray Backscatter Detectors
By Mark Guseman
TopicsSource of x-rays Interaction with matterDetection and ProcessingFooling the DetectorHealth Concerns
Source: Towe and Jacobs 1981
Source of X-Rays
•Two guns used in airport detectors•Low energy gun is equivalent to CAT scan source•High energy gun is stronger than used in a mammogram•Can either move the source or the object to be imagedSource: Kaufman and Carlson 2010
Compton ScatteringUc = K1pnf(E) gives the Compton coefficientRatio of penetration depths between two
output fluxes is given by x2 = x1 u2/u1ln(I2/I1)Penetration depth depends on energy,
intensity, and object density
Source: Towe and Jacobs 1981
Detecting Backscatter
Source: Herr et al 1994
Subtraction of Images
Source: Towe and Jacobs 1981
Modern Backscatter
Source: Kaufman and Carlson 2010
Fooling the DetectorMonte Carlo simulation using parameters from
real detectorsCylindrical tissue represents the abdomenRan simulation four times:
No added material 160 g of added tissue 190 g of added TATP explosive 320 g of added PETN explosive
Formed cone of material 20 cm in diameter and 1 cm high at center
Source: Kaufman and Carlson 2010
Source: Kaufman and Carlson 2010
Source: Kaufman and Carlson 2010
Health ConcernsAbout 1 μSv dose per exposure.This results in increased cancer risk of 10-7 per
round tripWith 1 billion exposures per year, the
population risk is no longer minimalMillimeter wave imaging, which is non-ionizing,
may provide a viable imaging alternative for airport security
Source: Brenner 2011
Works Cited
