Low-dose radiographic imaging system

• US 9,218,933 B2
• Filed: 09/19/2014
• Issued: 12/22/2015
• Est. Priority Date: 06/09/2011
• Status: Active Grant

• Current Assignee: Rapiscan Systems Incorporated (OSI Systems Incorporated)
• Original Assignee: Rapiscan Systems Incorporated (OSI Systems Incorporated)
• Inventors: Langeveld, Willem Gerhardus Johannes, Bendahan, Joseph, Gozani, Tsahi, King, Michael, Strellis, Dan, Franco, Edward, Alfonso, Krystal R.
• Primary Examiner(s): Midkiff, Anastasia
• Application Number:
  US14/491,825
• Publication Number:
  US 20150325401A1
• Time in Patent Office: 459 Days
• Field of Search: 378/62, 378/106, 378113-116, 378/119, 378/121, 378/136, 378/137, 378/145, 378/146, 378/204, 378/210, 250/370.09, 250/396.R, 250/396.ML, 250/397, 250/398, 250/427, 250/493.1, 250/503.1, 250/505.1, 250/526
• US Class Current: 1/1
• 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
• CPC Class Codes: G21K 1/02 using diaphragms, collimators
• CPC Class Codes: G21K 1/093 by magnetic means
• CPC Class Codes: H01J 2235/081 Target material
• CPC Class Codes: H01J 2235/086 Target geometry
• CPC Class Codes: H01J 35/08 Anodes; Anti cathodes
• CPC Class Codes: H01J 35/147 Spot size control
• CPC Class Codes: H01J 35/30 by deflection of the cathode ray
• CPC Class Codes: H01J 35/32 Tubes wherein the X-rays are produced at or near the end of the tube or a part thereof which tube or part has a small cross-section to facilitate introduction into a small hole or cavity
• CPC Class Codes: H01J 37/14 magnetic
• CPC Class Codes: H01J 37/141 Electromagnetic lenses
• CPC Class Codes: H01J 37/147 Arrangements for directing or deflecting the discharge along a desired path H01J37/045 take precedence; lenses H01J37/10
• CPC Class Codes: H01J 37/1472 Deflecting along given lines
• CPC Class Codes: H01J 37/1475 magnetic
• CPC Class Codes: H01J 37/3178 for applying thin layers on objects
• CPC Class Codes: H05G 1/52 Target size or shape; Direction of electron beam, e.g. in tubes with one anode and more than one cathode
• CPC Class Codes: H05G 2/00 Apparatus or processes specially adapted for producing X-rays, not involving X-ray tubes, e.g. involving generation of a plasma X-ray lasers H01S4/00

Abstract

An inspection system for scanning cargo and vehicles is described which employs an X-ray source that includes an electron beam generator, for generating an electron beam; an accelerator for accelerating said electron beam in a first direction; and, a first set of magnetic elements for transporting said electron beam into a magnetic field created by a second set of magnetic elements, wherein the magnetic field created by said second set of magnetic elements causes said electron beam to strike a target such that the target substantially only generates X-rays focused toward a high density section in the scanned object, which is estimated in a second pulse using image data captured by a detector array in a first pulse. The electron beam direction is optimized by said X-ray source during said second pulse to focus X-rays towards said high density section based on said image data in said first pulse.

Claims

1. An X-ray source for scanning an object comprising:

an electron beam generator, wherein said electron beam generator generates an electron beam;

an accelerator for accelerating said electron beam in a first direction; and

,

a first set of magnetic elements for transporting said electron beam into a magnetic field created by a second set of magnetic elements, wherein the magnetic field created by said second set of magnetic elements causes said electron beam to strike a target such that the target substantially only generates X-rays focused toward a high density area in the scanned object.

2. The X-ray source of claim 1, wherein said high density section in the scanned object is estimated in a second pulse using image data captured by a detector array in a first pulse and wherein the direction of the electron beam is optimized by said X-ray source during said second pulse to focus X-rays towards said high density area in the scanned object based on said image data in said first pulse.

3. The X-ray source of claim 2, wherein the intensity of the electron beam is optimized in each pulse to ensure that targeted areas in the scanned object are irradiated with an optimal dose of X-rays.

4. The X-ray source of claim 1, wherein said magnetic field causes said electron beam to strike the target at the same point but at a different angle in each successive pulse such that the angle at which said electron beam strikes the target depends on the position of the high density area in the scanned object.

5. The X-ray source of claim 1, wherein said magnetic field causes said electron beam to strike the target at the same point from different directions in successive pulses.

6. The X-ray source of claim 1, wherein said electron beam comprises single energy radiation.

7. The X-ray source of claim 6, wherein said first set of magnetic elements comprise a pulsed dipole magnet and said second set of magnetic elements comprise a quadrupole magnet.

8. The X-ray source of claim 1, wherein said electron beam comprises dual energy radiation.

9. The X-ray source of claim 8, wherein said first set of magnetic elements comprise a pulsed dipole magnet and said second set of magnetic elements comprise a pulsed quadrupole magnet.

10. The X-ray source of claim 8, wherein said first set of magnetic elements comprise a pulsed dipole magnet and said second set of magnetic elements comprise two quadrupole magnets, wherein each quadrupole magnet is configured to transport at least one of the radiation energies in the dual energy radiation beam.

11. The X-ray source of claim 1, wherein said target is manufactured from a material having low atomic number.

12. The X-ray source of claim 11 wherein said target is manufactured from carbon, graphite or diamond.

13. The X-ray source of claim 1, wherein said target is shaped.

14. The X-ray source of claim 13 wherein said target is of a semi-circular, triangular, or flat shape.

15. The X-ray source of claim 1, further comprising shielding optimized to reduce the system weight.

16. The X-ray source of claim 1, wherein said linear accelerator is mounted in a substantially vertical direction.

17. An inspection system for scanning cargo or vehicles comprising:

an X-ray source for generating an electron beam;

an accelerator for accelerating said electron beam in at least one predefined direction;

a first set of magnetic elements for transporting said electron beam into a magnetic field created by a second set of magnetic elements, wherein the magnetic field created by said second set of magnetic elements causes said electron beam to strike a target such that it substantially only generates X-rays focused toward a specific high density area in the scanned object; and

,

an X-ray detector array for detecting the radiation transmitted through the object under inspection.

18. The system of claim 17, wherein said inspection system is mounted on a mobile inspection vehicle.

19. The system of claim 17, wherein said high density area in the scanned object is estimated in a second pulse using image data captured by the detector array in a first pulse and wherein the direction of electron beam is optimized by said X-ray source during said second pulse to focus X-rays towards said high density area in the scanned object based on said image data in said first pulse.

20. The system of claim 17, wherein the intensity of electron beam is optimized for each pulse to ensure that targeted areas in the scanned object are radiated with an optimal dose of X-rays.

21. The system of claim 17, wherein said magnetic field causes said electron beam to strike the target at the same point but at a different angle in each successive pulse such that the angle at which said electron beam strikes the target depends on the position of high density area in the scanned object.

22. The system of claim 17, wherein said magnetic field causes said electron beam to strike the target at different points in successive pulses.

23. The system of claim 17, wherein said electron beam comprises single energy radiation.

24. The system of claim 23, wherein said first set of magnetic elements comprise a pulsed dipole magnet and said second set of magnetic elements comprise a quadrupole magnet.

25. The system of claim 17, wherein said electron beam comprises dual energy radiation.

26. The system of claim 25, wherein said first set of magnetic elements comprise a pulsed dipole magnet and said second set of magnetic elements comprise a pulsed quadrupole magnet.

27. The system of claim 25, wherein said first set of magnetic elements comprise a pulsed dipole magnet and said second set of magnetic elements comprise two quadrupole magnets wherein each quadrupole magnet is configured for transporting at least one of the radiation energies in the dual energy radiation beam.

28. The system of claim 17, wherein said target is manufactured from a material having low atomic number.

29. The system of claim 18 wherein said target is manufactured from carbon, graphite, or diamond.

30. The system of claim 17, wherein said target is shaped.

31. The system of claim 30, wherein said target is of a semi-circular, triangular, or flat shape.

32. The system of claim 17, further comprising a shielding optimized to reduce the system weight.

33. The system of claim 17, wherein said X-ray source is a linear accelerator mounted in a substantially vertical direction.

34. The system of claim 17, wherein said system further conducts transmission Z-spectroscopy to analyze at least one material contained in the scanned object.

35. The system of claim 17, wherein said system further conducts noise spectroscopy to analyze at least one material contained in the scanned object.

36. The system of claim 17, further comprising at least one X-ray filter for vertically modulating x-ray intensity.

37. The system of claim 17, wherein said X-ray detector array comprises one or more gapless X-ray detector arrays to detect the radiation transmitted by the scanned objects.

38. The system of claim 37, wherein said gapless detector array comprises a two-dimensional array of small detector elements and wherein each detector element comprises a scintillator.

39. The system of claim 17, further comprising a neutron-based inspection subsystem comprising a pair of neutron generators and a plurality of gamma-ray detectors.

40. An X-ray source for scanning an object comprising:

an electron beam generator, wherein said electron beam generator generates an electron beam;

an accelerator for accelerating said electron beam in a first direction; and

,

a first set of magnetic elements for transporting said electron beam into a magnetic field created by a second set of magnetic elements, wherein the magnetic field created by said second set of magnetic elements causes said electron beam to strike a target such that the target generates X-rays, wherein a majority of the X-rays are focused on a high density area in the scanned object and a minority of the X-rays are focused elsewhere.

41. An X-ray source for scanning an object comprising:

an accelerator capable of generating a sequence of pulsed electron beams of two or more different energies moving in a pre-defined direction, wherein a first pulse is low energy, a second pulse is high energy and each subsequent pulse in the sequence alternates between low energy and high energy; and

,

a set of electron steering components which causes the beam to strike the same area of the target at pre-defined angles, wherein said angle is estimated from at least one image captured from any previous pulse in the sequence of pulses of said electron beam.

42. The X-ray source of claim 41 wherein the steering components include a pulsed steering magnet and a pulsed quadrupole.

43. The X-ray source of claim 41 wherein the steering components include a pulsed steering magnet and at least two DC magnets.

44. The X-ray source of claim 41 wherein the low energy beam ranges from 4 MeV to 6 MeV and the high energy beam ranges from 6 MeV to 10 MeV.

45. The X-ray source of claim 41 wherein the target is fabricated from tungsten, a low-z material such as graphite, or copper depending upon the application.