Detection with Spectral X-Ray Detectors and the Complimentary Method … · 100000 120000 140000...
Transcript of Detection with Spectral X-Ray Detectors and the Complimentary Method … · 100000 120000 140000...
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Detection with Spectral X-Ray Detectors and the Complimentary Method of X-Ray Diffraction Ed Franco, Jonathan Kerner, Winston Chow, Ed Morton, and the team from MultiX
Presented at the ALERT ADSA Workshop 09: New Methods for Explosive Detection
for Aviation Security, October 22-23, 2013 Northeastern University, Boston, MA
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Rapiscan Proprietary Information
Conclusions
These Approaches Show Promise for Improving
Performance Based on Laboratory Results
- Multi-energy imaging improves material discrimination and
segmentation
- Coherent x-ray scatter provides material specific signatures
Additional R&D Required for Aviation Screening
- Multi-energy imaging and scatter are part of an evolving
concept for material identification
- Development and testing of systems under practical CONOPS
- Screening for HMEs remains a challenging application
- Research partnerships may accelerate development
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The Challenge
Dual-Energy Systems are Used to Screen for
Aviation Threats
- Achieves high PD with an operationally acceptable PFA
- Commercial and military explosives are generally well
separated from benign items in r-Zeff space
Screening for Home Made Explosives (HMEs)
- HMEs are variable due the way they are produced (raw
materials, impurities, and manufacturing processes) and
chemical effects (aging)
- Significant overlap with benign items in r-Zeff space
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Rapiscan Investigating Multiple Approaches to Improve Detection and Reduce False Alarms
Multi-Energy Imaging
- Better measurement of r and Zeff
Coherent X-Ray Scatter
- Provides orthogonal signature related to atomic structure
Other Approaches
- Tomography
- Phase contrast
- Compressive sensing
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Dual-Energy (DE) vs. Multi-Energy (ME) Imaging
DE uses two broad overlapping LE and HE bands
ME uses the entire transmitted spectrum
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Sp
ectr
a m
ea
su
red
by d
ete
cto
r
Energy (keV)
Air LE
Air HE
Air CdTe
Calculated absorption in DE and ME detectors DE (top) and ME (bottom) detector modules
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Result of clutter is enlarged “cloud”
of uncertainty on absolute value
DE vs ME Accuracy
Para
mete
r 2
Parameter 1
DE Uncertainty
ME Uncertainty
Clutter shifts measured value
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Effect of Clutter in Bags
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Multi-Energy Imaging
Benefits
- Improved material discrimination due to increased
accuracy and precision in the measurement of Zeff and
density
- Improved segmentation due to improved resolution and
image quality
Shows promise for improved PD and PFA
BUT clutter is a problem in quantitative imaging …
Future efforts are focused on cargo, checkpoint, and
hold-baggage applications
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Rapiscan has over 10 years experience with XRD and Coherent X-Ray Scatter
University Collaborations - “Energy dispersive X-ray scatter for measurement
of oil/water ratios”, Luggar, R. D.; Key, M. J.;
Morton, E. J.; Gilboy, W. B.; NIM, Sec A, V 422,
p. 938-941 (1999).
Bulk Explosives
- Rapiscan XRD1000 system
used XRD for alarm clearing
Home-Made Explosives
- Proprietary technology XRD1000 Baggage Inspection System
Combined dual-view, dual-energy imaging
with integrated XRD subsystem
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Pencil Beam Coherent X-ray Scatter Geometry
Pencil beam geometry is very simple
- However not very efficient
- Probes only a single point
Rapiscan is investigating more efficient geometries
X-ray source Sample CZT detectors
Scatter angle ~ 5 degrees 160 kV, 5 mA
Tungsten anode
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Produces Unique Material-Dependent Transmission and Scatter Signatures
• Bulk and HME explosives
Stream-of-passenger items
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Raw Transmission Spectra Raw Coherent X-ray Scatter Spectra
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Processed and Normalized Scatter Signature
Scatter signatures of threat materials distinguishable
from benign materials (see red ovals)
Can be used in automated classification algorithms
Threat Materials Benign Substances
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Conclusions
These Approaches Show Promise for Improving
Performance Based on Laboratory Results
- Multi-energy imaging improves material discrimination and
segmentation
- Coherent x-ray scatter provides material specific signatures
Additional R&D Required for Aviation Screening
- Multi-energy imaging and scatter are part of an evolving
concept for material identification
- Development and testing of systems under practical CONOPS
- Screening for HMEs remains a challenging application
- Research partnerships may accelerate development