Method and apparatus for transmitting information about a target object between a prescanner and a CT scanner

• US 6,944,264 B2
• Filed: 11/06/2003
• Issued: 09/13/2005
• Est. Priority Date: 02/06/2002
• Status: Expired due to Fees

• Current Assignee: Leidos Security Detection & Automation Incorporated (Leidos Holdings, Inc.)
• Original Assignee: L-3 Communications Security and Detection Systems Corporation Delaware
• Inventors: Eilbert, Richard F., Shi, Shunghe, Bijjani, Richard R.
• Primary Examiner(s): Ho, Allen C.
• Application Number:
  US10/702,814
• Publication Number:
  US 20050094765A1
• Time in Patent Office: 677 Days
• Field of Search: 378/5, 378/57, 378/98.9
• US Class Current: 378/57
• CPC Class Codes: G01N 2223/402 mapping distribution of elements
• CPC Class Codes: G01N 2223/419 computed tomograph
• CPC Class Codes: G01N 2223/421 digitised image, analysed in real time (recognition algorithms)
• CPC Class Codes: G01N 23/046 using tomography, e.g. computed tomography [CT]
• CPC Class Codes: G01N 23/087 using polyenergetic X-rays
• CPC Class Codes: G01V 5/224 Multiple energy techniques using one type of radiation, e.g. X-rays of different energies
• CPC Class Codes: G01V 5/226 using tomography

Abstract

A method or apparatus for analyzing an object includes an X-ray prescanner that performs a prescan of the object to determine prescan information about the object. Then, a CT scanner performs a CT scan on at least one plane of the object based on the prescan information to determine CT information. In one embodiment, if the CT scan of the object includes or is in the vicinity of metal, then metal artifact correction of a reconstructed image from the CT scan is performed based on the prescan information. In another embodiment, a processor analyzes the CT information and the prescan information to determine whether to update the prescan information based on the CT information.

Claims

1. A method of screening an item to detect target objects therein, comprising:

a) passing X-rays through the item at a plurality of energies;

b) detecting X-rays that have passed through the item to produce detected values representative of the intensity of the detected X-rays;

c) analyzing the detected values, without performing a computed tomographic reconstruction thereon, to produce at least one second values that identifies an effective atomic number of at least one region in the item;

d) using the at least one second value to obtain a sinogram representative-of only a portion of a slice through the object; and

e) using a computed tomography computation to reconstruct a partial image of the item based upon the sinogram representative of only a portion of the item.

2. The method of claim 1 wherein the partial image of the item is a clip in the vicinity of a metal object.

3. The method of claim 2 wherein, using at least one second value to obtain a sinogram representative of only a portion of the item comprises generating the sinogram from an altered clip of an image.

4. The method of claim 1 wherein the sinogram is determined by creating a computed tomography image of the item, clipping that image and creating a sinogram of the clipped image.

5. An explosive detection system comprising:

a) a scanner having an output to provide scan data of an item under inspection;

b) an operator display having an input to receive data representative of an image to display for an operator; and

c) at least one processor coupled to the output of the scanner to receive scan data and coupled to the input of the operator display, the at least one processor being programmed to, based on the scan data;

i) process the scan data to produce data representative of a two dimensional projection of at least a portion of the item;

ii) identify at least one object in the item;

iii) provide to the display data representative of an image that comprises the two dimensional projection;

iv) process the scan data to generate a computed tomographic representation of at least a portion of the item; and

v) augment the data representative of the two dimensional projection based on information obtained from the computed tomographic representation.

6. The explosive detection system of claim 5 wherein the scanner comprises a dual energy CT scanner.

7. The explosive detection system of claim 6 wherein the system further comprises an Ethernet connection that couples the at least one processor to the dual energy CT scanner.

8. The explosive detection system of claim 6 wherein the at least one processor is programmed to compute an estimate of effective atomic number of pixels representing the item under inspection.

9. The explosive detection system of claim 8 wherein the at least one processor is programmed to identify as an object a collection of pixels in close proximity having effective atomic number values falling in a range.

10. The explosive detection system of claim 8 wherein the at least one processor is programmed to augment information by modifying the estimate of atomic number of a selected object.

11. The explosive detection system of claim 8 wherein the at least one processor is programmed to augment information by modifying an estimate of the mass of a selected object.

12. The explosive detection system of claim 5 wherein the at least one processor is programmed to generate a computed tomography representation of a portion of the object in a slice transverse to the plane of the two dimensional image.

13. The explosive detection system of claim 5 wherein the at least one processor is programmed to generate a computed tomography representation of a portion of the object in a slice in the direction of the angle from which the two dimensional image is formed.

14. The explosive detection system of claim 5 wherein the scanner comprises two x-ray sources.

15. The explosive detection system of claim 5 wherein the at least one processor is external to the scanning unit.

16. The explosive detection system of claim 5 wherein the at least one processor is programmed to perform a threat detection algorithm.

17. The explosive detection system of claim 16 wherein the threat detection algorithm outputs an indication of whether an object is a threat.

18. The explosive detection system of claim 5 wherein the representation of the two dimensional projection includes indications of the at least one object therein.

19. The explosive detection system of claim 18 wherein the at least one processor is programmed to receive input from a human operator concerning whether the at least one object is a potential threat object.

20. The explosive detection system of claim 5 wherein the scanner is a single unit operable to provide line scanning and CT scanning functionality.

21. The explosive detection system of claim 20 wherein the single unit is a dual energy x-ray scanner.

22. The explosive detection system of claim 5 wherein the two dimensional projection of the item under inspection is in a first plane and the computed tomographic representation is of a portion of the item transverse to the first plane.

23. The explosive detection system of claim 5 wherein the at least one processor is programmed to augment information about the at least one object by computing an estimate of the mass of the at least one object.

24. The explosive detection system of claim 5 wherein the at least one processor creates a first data structure storing characteristics of the at least one object in the item derived from a representation of a two dimensional projection of the item and augments information about the at least one object by storing in a data structure characteristics derived from the computed tomographic representation of a portion of the item.

25. The explosive detection system of claim 5 wherein data representative of the two dimensional projection is stored in a first data table and information obtained from the computed tomographic representation is stored in a second data table, and wherein the at least one processor is programmed to augment the data representative of the two dimensional projection by synthesizing information from the first table and the second table.

26. The explosive detection system of claim 5 wherein data representative of the two dimensional projection is stored in a first data table and information obtained from the computed tomographic representation is stored in a second data table and data representative of the two dimensional projection is augmented by synthesizing information from the first table and the second table by altering information in the first table based on information in the second table.

27. A method for analyzing an item, comprising acts of:

a) analyzing scan data that provides a projection of the item to determine a value of at least one first characteristic of at least one object in the item;

b) selecting, based on the projection, a region of the item;

c) performing a computed tomographic reconstruction of the selected region to produce a reconstructed representation of the selected region; and

d) modifying the value determined for the at least one first characteristic of the at least one object in the act (a) based on the reconstructed representation.

28. The method of claim 27 additionally comprising the act of determining at least one second characteristic associated with objects in the selected region.

29. The method of claim 28 wherein the act of modifying the value determined for the at least one first characteristic comprises selectively changing the value of the at least one first characteristic based on the value of the at least one second characteristic.

30. The method of claim 29 wherein the selected region comprises at least one slice of the item.

31. The method of claim 29 wherein the first characteristic comprises the effective atomic number of the object.

32. The method of claim 29 wherein the first characteristic is an estimated mass of the object.

33. The method of claim 29 wherein the at least one first characteristic comprises effective atomic number and mass of the at least one object.

34. The method of claim 33 wherein the projection is in a first plane and the act of analyzing scan data to determine a value of at least one first characteristic comprises analyzing scan data to determine a representation of the position of the object in that plane.

35. The method of claim 34 wherein the act of determining at least one second characteristic comprises determining a representation of the position of the at least one object in a second plane, transverse to the first plane.

36. The method of claim 35 wherein the act of determining at least one second characteristic comprises determining a representation of the boundaries of the at least one object in the second plane.

37. The method of claim 27 wherein the act of modifying the value for the at least one first characteristic comprises augmenting the at least one first characteristic associated with at least one object with information obtained from the reconstructed representation.