SYSTEM AND METHOD FOR XRD-BASED THREAT DETECTION

• US 20090213989A1
• Filed: 02/23/2009
• Published: 08/27/2009
• Est. Priority Date: 02/22/2008
• Status: Active Grant

• Current Assignee: Morpho Detection (Safran SA)
• Original Assignee: Morpho Detection (Safran SA)
• Inventors: Harding, Geoffrey
• Granted Patent: US 7,924,978 B2
• Time in Patent Office: Days
• US Class Current: 378/57
• CPC Class Codes: G01N 2223/419 computed tomograph
• CPC Class Codes: G01N 2223/629 welds, bonds, sealing compounds
• CPC Class Codes: G01N 2223/66 multiple steps inspection, e.g. coarse/fine
• CPC Class Codes: G01N 23/046 using tomography, e.g. computed tomography [CT]
• CPC Class Codes: G01N 23/207 Diffractometry using detectors, e.g. using a probe in a central position and one or more displaceable detectors in circumferential positions
• CPC Class Codes: G01V 5/222 measuring scattered radiation
• CPC Class Codes: G01V 5/226 using tomography
• CPC Class Codes: G21K 1/02 using diaphragms, collimators

Abstract

System and method for XRD-based threat detection. An object is scanned with a first threat detection system. One or more alarm objects are identified. Data about the one or more alarm objects is passed from the first threat detection system to a second threat detection system and is used to move and/or to rotate the object in a predetermined ray path that decreases attenuation of scattered x-ray radiation. Also disclosed is a secondary collimator for XRD-based false alarm resolution in computed tomography {“CT”) threat detection systems. The secondary collimator comprises one or more slit apertures configured to provide a multi-angle capability that extends a range of momenta for which XRD intensities are measured for a predetermined range of photon intensities.

Claims

1. A method, comprising:

scanning an object with a first threat detection system to obtain image data of the container;

processing the obtained image data to reconstruct an image of the object;

processing the reconstructed image to identify a region of the image that contains an alarm object;

moving the container to align the alarm object for scanning by a second threat detection system; and

rotating the container to place the alarm object in a predetermined ray path that decreases x-ray attenuation.

2. The method of claim 1, further comprising:

adjusting a source collimator of the second threat detection system to irradiate the alarm object with a beam of x-ray radiation;

focusing an x-ray detector to receive the x-ray radiation; and

analyzing a signal output from the x-ray detector to confirm or clear the alarm object.

3. The method of claim 1, wherein the first threat detection system is a computed tomography (“

CT”

) system.

4. The method of claim 3, wherein the second threat detection system is an x-ray diffraction (“

XRD”

) system.

5. The method of claim 1, wherein the object is a shipping container.

6. The method of claim 1, wherein the object is a piece of luggage.

7. The method of claim 1, further comprising:

transferring data about the alarm object to the second threat detection system.

8. The method of claim 7, wherein the data about the alarm object comprises at least one of the following:

(a) a single-dimensional geometrical position of the alarm object in the object;

(b) a multi-dimensional geometrical position of the alarm object in the object;

(c) a geometry of the predetermined ray path from an x-ray source to a corresponding detector in a horizontal plane that contains the alarm object;

(d) a value of an object density integrated along the predetermined ray path; and

(e) a spatial distribution of the alarm object along the predetermined ray path.

9. A system, comprising:

a first threat detection system configured to scan an object for a presence of an alarm object and to identify data about the alarm object;

a second threat detection system coupled with the first threat detection system;

wherein the first threat detection system is configured to transmit the data about the detected one or more alarm objects to the second threat detection system to initiate movement and/or rotation of the object into alignment with a predetermined ray path that decreases x-ray attenuation.

10. The system of claim 9, wherein the first threat detection system is a computed tomography (“

CT”

) system.

11. The system of claim 9, wherein the second threat detection system is an x-ray diffraction (“

XRD”

) system.

12. A secondary collimator, comprising:

a body formed of a high density material; and

a continuous spiral slit aperture formed in the body, wherein the continuous spiral slit aperture provides a multi-angle capability that extends a range of momenta for which XRD intensities are measured for a predetermined range of photon intensities.

13. A secondary collimator, comprising:

a body formed of a high density material; and

multiple slit apertures formed in the body and arranged at different distances from a primary beam aperture and/or axis.

17. The threat detection system of claim 13, wherein the first predetermined scatter angle and the second predetermined scatter angle each satisfy:

${\mathrm{\theta <br><br>}}_i={\tan }^{-1}<br><br>\left(\frac{a_i}{S-x_v}\right)$

wherein, a_i is the distance of an ith secondary collimator slit from the axis;

S is a position (x coordinate) of the secondary collimator referred to the x-ray source; and

x_v is an x coordinate of a voxel in which scattering originates.

18. The threat detection system of claim 13, wherein the one or more apertures comprises:

multiple slit apertures formed in a body of the secondary collimator and arranged at different distances from a primary beam aperture and/or axis.

14. A threat detection system, comprising an x-ray source configured to irradiate an alarm object within an object;

a plurality of x-ray detectors positioned apart from the x-ray source, wherein the plurality of x-ray detectors comprises a first detector positioned along an axis parallel to a primary beam of radiation and a first scatter detector and a second scatter detector positioned between the first detector and the x-ray source;

a secondary collimator positioned between the first scatter detector and the second scatter detector, wherein the secondary collimator comprises one or more slit apertures,

wherein the first scatter detector is disposed at a first predetermined scatter angle with respect to the axis and the second scatter detector is disposed at a second predetermined scatter angle with respect to the axis to capture photons scattered from a scan area of the object along predetermined ray paths that pass through the secondary collimator'"'"'s one or more slit apertures.

15. The threat detection system of claim 14, wherein the scan area comprises all or part of a suspicious area, or alarm object(s), that a previous scan identified in the object.

16. The threat detection system of claim 14, wherein the collimator comprises a body formed of a high density material, and wherein the one or more slit apertures of the collimator comprises:

a continuous spiral slit aperture formed in the body, wherein the continuous spiral slit aperture provides a multi-angle capability that extends a range of momenta for which XRD intensities are measured for a predetermined range of photon intensities.