Methods and systems for the rapid detection of concealed objects

Abstract

The present invention provides for an improved scanning process having a first stage to rapidly identify a threat location and a second stage to accurately identify the nature of the threat. The improved scanning process maintains a high degree of accuracy while still providing an operationally desirable high throughput. The present invention also uses improved processing techniques that enable the substantially automated detection of threats and decrease the dependence on operator accuracy. One embodiment of the present invention provides an apparatus for identifying an object concealed within a container. It comprises a first stage inspection system having at least two X-ray projection systems to generate a first set of data and a plurality of processors in data communication with the first stage inspection system. The processors process the first set of data to generate at least two images. The two images are used to identify at least one target region from the two images. A second stage inspection system is then used to generate an inspection region which is then positioned relative to the target region and made to at least partially physically coincide with the target region. A second set of data is produced specifically from the inspection region, data which have a high degree of specificity for the material in the inspection region.

Description

FIELD OF THE INVENTION The present invention relates generally to X-ray based methods and systems for detection of concealed threats, and threat resolution, and more specifically to improved methods and systems, using dual stage scanning to process luggage for faster inspection with reduced false alarm rate. BACKGROUND OF THE INVENTION Conventional X-ray systems produce radiographic projection images, which are then interpreted by an operator. These radiographs are often difficult to interpret because objects are superimposed. A trained operator must study and interpret each image to render an opinion on whether or not a target of interest, a threat, is present. With a large number of such radiographs to be interpreted, and with the implied requirement to keep the number of false alarms low, operator fatigue and distraction can compromise detection performance. Advanced technologies, such as dual-energy projection imaging and Computed Tomography (CT), are being used for contraban...

AI Technical Summary

Benefits of technology

One object of the present invention is to provide for an improved scanning process having a first stage to pre-select the locations of potential threats and a second stage to accurately identify the nature of the threat. The improved scanning process increases throughput by limiting the detailed inspection to a small fraction of the total bag volume, and it decreases processing system in data communication with the first stage inspection system. The processors process the first set of data to generate at least two images or image data files. The images are then subjected to a set of image interpretation algorithms, also processed by the processors, to identify target regions in the two images. Since the images are projected in different direction it is possible to back-project identified target regions and to locate those targets in system coordinates.

Problems solved by technology

These radiographs are often difficult to interpret because objects are superimposed.

With a large number of such radiographs to be interpreted, and with the implied requirement to keep the number of false alarms low, operator fatigue and distraction can compromise detection performance.

However, the dual-energy method does not readily allow for the calculation of the actual atomic number of the concealed ‘threat’ itself, but rather yields only an average atomic number that represents the mix of the various items falling within the X-ray beam path, as the contents of an actual luggage is composed of different items and rarely conveniently separated.

Thus dual-energy analysis is often confounded.

Even if the atomic number of an item could be measured, the precision of this measurement would be compromised by X-ray photon noise to the extent that many innocuous items would show the “same” atomic number as many threat substances, and therefore the atomic number in principle cannot serve as a sufficiently specific classifier for threat versus no threat.

However, conventional CT systems take considerable time to perform multiple scans, to capture data, and to reconstruct the images.

The throughput of CT systems is generally low.

Coupled with the size and expense of CT systems this limitation has hindered CT use in applications such as baggage inspection where baggage throughput is an important concern.

In addition, CT alarms on critical mass and density of a threat, but such properties are not unique to explosives.

CT based systems suffer from high false alarm rate.

Each of the prior art systems and methods, however, suffer from low processing rates because the scatter interaction cross sections are relatively small and the exposure times required to obtain useful diffraction spectra are long, in the range of seconds and minutes.

However, the use of CT scanning is still inefficient, not threat specific, and does not allow for rapid scanning of objects.

The disclosed system does not, however, address critical problems that arise in the course of the frequency of false alarms by applying threat specific analysis.

These objects may be considered threats, such as an illegal drug, an explosive material, or a weapon.

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