Rapid X-ray inspection system

• US 5,910,973 A
• Filed: 07/22/1997
• Issued: 06/08/1999
• Est. Priority Date: 07/22/1996
• Status: Expired due to Term

• Current Assignee: American Science and Engineering Incorporated (OSI Systems Incorporated)
• Original Assignee: American Science and Engineering Incorporated (OSI Systems Incorporated)
• Inventors: Grodzins, Lee
• Primary Examiner(s): Porta, David P.
• Application Number:
  US08/898,165
• Time in Patent Office: 686 Days
• Field of Search: 378/57, 378/51, 378/53, 378/54, 378/56, 378/62, 378/146
• US Class Current: 378/57
• CPC Class Codes: G01N 23/04 and forming images of the material
• CPC Class Codes: G01V 5/22 Active interrogation, i.e. by irradiating objects or goods using external radiation sources, e.g. using gamma rays or cosmic rays

Abstract

An inspection system for automatically detecting the presence of a concealed item within an enclosure. A beam of penetrating radiation is incident on the enclosure and detected by a detector disposed on the side of the enclosure opposite to the incident beam. By scanning the relative orientation of the enclosure with respect to the beam, the penetrating radiation transmitted through the enclosure is mapped, compared with known properties of the enclosure, and the presence of material concealed within the enclosure is determined.

Claims

1. An inspection system for inspecting an enclosure having a spatial frame of reference, comprising:

(a) a source of penetrating radiation;

(b) a collimator for forming the penetrating radiation into a beam having an orientation with respect to the enclosure;

(c) a scanner arrangement for varying the orientation of the beam with respect to the enclosure such that a component of the beam traverses the enclosure;

(d) a detector for producing flux position distribution information, disposed so as to intercept the component of beam traversing the enclosure;

(e) a signal-processing means for transforming the position distribution information to an absorption distribution matrix referred to the spatial frame of reference of the enclosure; and

(f) a controller for determining the presence of concealed material within the enclosure based at least on the absorption distribution matrix and a specified detection criterion.

2. The inspection system as set forth in claim 1 wherein the source of penetrating radiation is an x-ray source.

3. The inspection system as set forth in claim 1 wherein the source of penetrating radiation is an x-ray tube.

4. The inspection system as set forth in claim 1 wherein the beam is a beam of specified cross section.

5. The inspection system as set forth in claim 1, wherein the beam is a fan beam.

6. The inspection system as set forth in claim 1, wherein the scanner arrangement includes a conveyor for transporting the enclosure through the beam.

7. The inspection system as set forth in claim 1, wherein the detector includes a liquid scintillator.

8. The inspection system as set forth in claim 7, wherein the liquid scintillator includes heavy metal doping.

9. The inspection system as set forth in claim 7, wherein the liquid scintillator includes tin doping.

10. The inspection system as set forth in claim 1, further comprising a computer memory for storing absorption matrices of standard enclosures.

11. The inspection system as set forth in claim 1, wherein said detector includes an array of photodetectors.

12. The inspection system as set forth in claim 1, further comprising an autocorrelator for detecting repeat patterns and significant changes of absorption of penetrating radiation as the component of the beam traverses the enclosure.

13. The inspection system as set forth in claim 1, further comprising a visual display for displaying an image based on the absorption distribution matrix.

14. A method for detecting the presence of concealed material within an enclosure, comprising:

(a) illuminating the enclosure with penetrating radiation propagating substantially along a beam having an orientation with respect to the enclosure;

(b) varying the orientation of the beam with respect to the enclosure such that a component of the beam traverses the enclosure;

(c) mapping an areal distribution of penetrating radiation transmitted through the enclosure;

(d) processing the areal distribution of penetrating radiation transmitted through the enclosure to obtain an absorption distribution matrix; and

(e)automatically determining the presence of concealed material within the enclosure.

15. The method for detecting the presence of concealed material within an enclosure according to claim 14, further comprising the step of comparing the absorption distribution matrix with stored absorption distribution matrices.

16. A method for detecting the presence of concealed material within an enclosure, comprising:

(a) illuminating the enclosure with penetrating radiation propagating substantially along a beam having an orientation with respect to the enclosure;

(b) varying the orientation of the beam with respect to the enclosure such that a component of the beam traverses the enclosure;

(c) mapping an areal distribution of penetrating radiation transmitted through the enclosure;

(d) autocorrelating the areal distribution of penetrating radiation transmitted through the enclosure; and

(e) determining the presence of concealed material within the enclosure.