Radiation scanning of objects for contraband

• US 7,103,137 B2
• Filed: 07/24/2002
• Issued: 09/05/2006
• Est. Priority Date: 07/24/2002
• Status: Expired due to Fees

• Current Assignee: Varex Imaging Corporation
• Original Assignee: Varian Medical Systems Incorporated (Siemens AG)
• Inventors: Seppi, Edward J., Ford, John, Marc, Marcel
• Primary Examiner(s): Glick, Edward J.
• Assistant Examiner(s): Yun, Jurie
• Application Number:
  US10/202,273
• Publication Number:
  US 20040017888A1
• Time in Patent Office: 1,504 Days
• Field of Search: 378/57, 378/58, 378/10, 378/9
• US Class Current: 378/9
• CPC Class Codes: G01N 2223/423 multispectral imaging-multiple energy imaging
• CPC Class Codes: G01N 23/04 and forming images of the material
• CPC Class Codes: G01T 1/2985 In depth localisation, e.g. using positron emitters; Tomographic imaging (longitudinal and transverse section imaging; apparatus for radiation diagnosis sequentially in different planes, steroscopic radiation diagnosis); using external radiation sources A61B6/02
• CPC Class Codes: G01V 5/226 using tomography

Abstract

A scanning unit for identifying contraband within objects, such as cargo containers and luggage, moving through the unit along a first path comprises at least one source of a beam of radiation movable across a second path that is transverse to the first path and extends partially around the first path. A stationary detector transverse to the first path also extends partially around the first path, positioned to detect radiation transmitted through the object during scanning. In one example, a plurality of movable X-ray sources are supported by a semi-circular rail perpendicular to the first path and the detector, which may be a detector array is also semi-circular and perpendicular to the path. A fan beam may also be used. Radiographic images may be obtained and/or computed tomography (“CT”) images may be reconstructed. The images may be analyzed for contraband. Methods of scanning objects are also disclosed.

Claims

1. A scanning unit for examining contents of an object movable along a predetermined first path, the scanning unit comprising:

a rail transverse to the first path;

one or more sources of respective beams of radiation, at least one of the one or more sources being supported by the rail and being movable across a second path transverse to the first path, along the rail, the second path extending only partially around the first path; and

a stationary detector extending only partially around the first path, the detector being positioned to detect radiation transmitted through the object during scanning.

2. The scanning unit of claim 1, wherein the object is a cargo container and the detector and the at least one source of radiation are positioned to allow the cargo container to be transported therebetween, along the first path.

3. The scanning unit of claim 2, wherein the cargo container is carried by a vehicle;

and

the detector and the at least one source of radiation are positioned to allow the cargo and the vehicle to be transported therebetween.

4. The scanning unit of claim 1, wherein the detector is located, at least in part, beneath the first path, below ground;

and

the at least one source is located above the first path.

5. The scanning unit of claim 1, wherein the second path is a semi-circle and the at least one of the one or more sources is movable about the semi-circle, the semi-circle lying on an imaginary circle having a center within the object when the object is in a position for scanning.

6. The scanning unit of claim 5, wherein:

the rail is a semi-circular rail perpendicular to the first path; and

a plurality of sources are supported by the rail and are movable with respect to the rail along the second path, about the semi-circle.

7. The scanning unit of claim 5, wherein the detector is a detector array comprising a semi-circular row of detectors perpendicular to the first path and lying on an imaginary circle having a center within the object when the object is in a position for scanning.

8. The scanning unit of claim 1, wherein the detector comprises a plurality of two dimensional detectors.

9. The scanning unit of claim 1, comprising at least one energy sensitive detector.

10. The scanning unit of claim 1, wherein the at least one source is a source of X-ray radiation.

11. The scanning unit of claim 1, wherein the beam is a cone beam.

12. The scanning unit of claim 1, further comprising a processor electrically coupled to the detector array, the processor being programmed to reconstruct computed tomography images based on data received from the detector array.

13. The scanning unit of claim 1, further comprising a transport system to convey the object through the scanning unit, along the first path.

14. The scanning unit of claim 1, wherein each of the at least one sources is a linear accelerator.

15. The scanning unit of claim 1, further comprising:

a transport system to transport an object along the first path.

16. The scanning unit of claim 1, wherein:

the rail is arcuate; and

the second path is arcuate.

17. A scanning unit for examining the contents of an object moving along a predetermined first path, the scanning unit comprising:

one or more sources of X-ray radiation, at least one of the one or more sources being adapted to provide a respective cone beam of X-ray radiation to irradiate the object and each of the at least one sources being mechanically movable across a single, common second path transverse to the first path, the second path extending only partially around the first path; and

a stationary detector extending only partially around the first path, the detector being positioned to detect radiation after a respective cone beam passes through the object during scanning;

wherein the second path and the detector extend sufficiently around the object to collect sufficient data for computed tomographic imaging.

18. The scanning unit of claim 17, wherein the object is a cargo container and the X-ray sources and the detector are positioned to allow transport of the cargo container therebetween.

19. The scanning unit of claim 17, further comprising:

a semi-circular rail supported by the scanning unit perpendicular to the first path,

the semi-circular rail lying on an imaginary circle having a center within the object when the object is in position for scanning,

wherein the rail supports the at least one of the one or more sources, the at least one of the one or more sources being movable in a semi-circle about the rail; and

the detector array is semi-circular,

is perpendicular to the path, and

lies on an imaginary circle having a center within the cargo when the cargo is in position for scanning.

20. The scanning unit of claim 17, wherein the detector is a detector array comprising a plurality of rows of detector modules.

21. The scanning unit of claim 17, wherein at least one of the sources emits radiation having a first energy distribution and at least one of the sources emits radiation having a second energy distribution different than the first energy distribution.

22. The scanning unit of claim 21, further comprising a second, energy sensitive, detector,

wherein the first detector is between the second detector and the plurality of sources.

23. The scanning unit of claim 22, further comprising a processor electrically coupled to the first and second detectors, the processor being programmed to:

reconstruct computed tomography images based on data received from the first detector;

reconstruct energy based images based on data received from the second detector; and

fuse the images based on data from the first detector array with the images based on the data received from the second detector.

24. The scanning unit of claim 17, wherein each of the plurality of sources are operational to selectively switch between emitting radiation having a first energy distribution and radiation having a second energy distribution different than the first energy distribution.

25. The scanning unit of claim 24, further comprising a second, energy sensitive, detector,

wherein the first detector is between the second detector and the plurality of sources.

26. The scanning unit of claim 25, further comprising a processor electrically coupled to the first detector, the processor being programmed to:

reconstruct computed tomography images based on data received from the first detector;

reconstruct energy based images based on data received from the second detector; and

fuse the images based on data from the first detector array with the images based on the data received from the second detector array.

27. The scanning unit of claim 17, further comprising a processor electrically connected to the detector, the processor being programmed to reconstruct computed tomography images based on data received from the detector.

28. The scanning unit of claim 17, wherein the cone beam is an asymmetric rectangular cone beam.

29. The scanning unit of claim 17, further comprising:

a transport system to transport the object along the first path.

30. The scanning system of claim 17, wherein:

the source and the detector are positioned to allow passage of a truck therebetween, to scan an object carried by the truck.

31. A cargo scanning unit comprising:

means for transporting a cargo container along a path through the scanning unit;

a semi-circular rail supported by the unit above the path, transverse to the path, the semi-circular rail lying on a first imaginary circle having a center within the cargo container when the cargo is in position for scanning;

a plurality of movable sources of X-ray radiation supported by the rail, each source to provide a cone beam of X-ray radiation; and

a semi-circular detector array having at least a portion below the path, beneath ground level, the detector array being transverse to the path and lying on a second imaginary circle having a center within the cargo container when the cargo container is in position for scanning;

wherein the first and second imaginary circles lie in a same plane; and

the detector array comprises a plurality of two dimensional detectors.

32. The cargo scanning unit of claim 31, wherein the detector array is stationary.

33. The cargo scanning unit of claim 31, wherein at least one of the sources emits radiation having a first energy distribution and at least one of the sources emits radiation having a second energy distribution different than the first energy distribution.

34. The cargo scanning unit of claim 33, further comprising a second, energy sensitive, detector array,

wherein the first detector array is between the second detector array and the plurality of sources.

35. The cargo scanning unit of claim 31, wherein each of the plurality of sources are operational to selectively switch between emitting radiation having a first energy distribution and radiation having a second energy distribution different than the first energy distribution.

36. The cargo scanning unit of claim 35, further comprising a second, energy sensitive, detector array,

wherein the first detector array is between the second detector array and the plurality of sources.

37. The cargo scanning unit of claim 31, wherein the X-ray sources are linear accelerators having acceleration potentials greater than about 1 MV.

38. The cargo scanning unit of claim 31, wherein the cone beam covers an angle of about 20 to about 30 degrees.

39. A method of examining contents of a cargo container, comprising:

moving at least one source of radiation along a single, common arc extending only partially around a cargo container;

scanning at least a portion of the cargo container with at least one respective radiation beam from the at least one source of radiation at a plurality of angles;

detecting radiation from the at least one source, transmitted through the cargo container; and

processing data based on the radiation detected from the at least one source moved along the single arc, to form computed tomographic images of at least the portion of the cargo container.

40. The method of claim 39, further comprising:

moving the cargo container along a path in a first direction;

scanning at least a portion of the cargo container by a plurality of radiation beams, each scanning the cargo container at a different angle; and

detecting radiation transmitted through the cargo container by a stationary detector.

41. The method of claim 40, further comprising:

moving a source of the radiation beam in a second direction transverse to the first direction to scan the cargo container; and

detecting radiation transmitted through the cargo container by a stationary detector.

42. The method of claim 39, comprising scanning the cargo container with a cone beam of radiation.

43. The method of claim 39, comprising scanning the cargo container with X-ray radiation.

44. The method of claim 39, comprising scanning the cargo container with a radiation beam having a first energy distribution and scanning the cargo container with a radiation beam having a second energy distribution different from the first energy distribution.

45. The method of claim 44, comprising:

detecting radiation with a first, spatial detector;

detecting radiation with a second, energy sensitive, detector; and

processing data based on the detected radiation from the first and second detectors to form respective computed tomographic images of the cargo container.

46. The method of claim 45, comprising:

fusing corresponding computed tomographic images from the radiation detected from the first and second detectors.

47. The method of claim 39, further comprising:

first;

scanning the entire cargo container with a beam of radiation,

producing radiographs of the cargo container, and

identifying suspicious regions of the cargo container based on the radiographs, and then;

scanning the suspicious regions of the cargo container with a radiation beam at the plurality of angles,

detecting radiation transmitted through the cargo container, and

processing data based on the detected radiation to form computed tomographic images of the suspicious regions of the cargo container.

48. The method of claim 47, comprising scanning the entire cargo container with a pencil beam of radiation.

49. The method of claim 39, comprising scanning a cargo container having a height and/or width of at least about 1.5 meters.

50. The method of claim 39, comprising:

mechanically moving the at least one source of radiation along an arcuate rail.

51. The method of claim 39, wherein the cargo container is supported by a truck, the method further comprising:

moving the truck and the cargo container between the at least one source and the detector during scanning.

52. A method of examining contents of an object, comprising:

moving the object along a first path;

moving at least one source of a radiation beam along a second path transverse to the first path, along a rail, to scan the object, the second path extending only partially around the first path; and

detecting radiation transmitted through the object by a stationary detector array, the detector array extending only partially around the first path.

53. The method of claim 52, comprising reconstructing images based on the detected radiation.

54. The method of claim 53, comprising reconstructing computed tomography images based on the detected radiation.

55. The method of claim 52, comprising:

irradiating the object with a first radiation beam having a first energy distribution; and

irradiating the object with a second radiation beam having a second energy distribution different from the first energy distribution.

56. The method of claim 55, comprising:

detecting radiation transmitted through the object with a first, spatial detector array; and

detecting radiation transmitted through the object with a second, energy sensitive, detector.

57. The method of claim 56, comprising:

reconstructing computed tomography images from the radiation detected by the first detector;

reconstructing images from the radiation detected by the second detector; and

fusing corresponding images from the radiation detected from the first and second detectors.

58. The method of claim 56, comprising:

detecting radiation from the first radiation beam transmitted through the object;

detecting radiation from the second radiation beam transmitted through the object;

computing a first value based on the detected radiation from the first radiation beam, for a plurality of voxels of the object;

computing a second value based on the detected radiation from the second radiation beam, for the plurality of voxels of the object;

processing the first and second values for the plurality of voxels; and

determining a material content of the plurality of voxels based on the processing.

60. The method of claim 52, further comprising:

identifying suspicious regions of the object;

then

irradiating the suspicious regions at a plurality of angles with a radiation beam from the at least one moving source;

detecting radiation caused by the interaction of the suspicious regions with the radiation beam; and

reconstructing computed tomography images of the suspicious regions from the detected radiation.

61. The method of claim 52, comprising moving a cargo container along the first path.

62. The method of claim 61, comprising supporting the cargo container on a truck.

63. The method of claim 52, further comprising generating a cone beam to scan the object.

64. The method of claim 52, comprising:

moving the at least one source along a semi-circular second path along a semi-circular rail.

59. The method of 58, comprising;

processing the first and second values by computing a ratio of the first and second values for the plurality of voxels; and

determining the material content of the plurality of voxels based on the ratio.

65. A scanning unit for examining a target movable along a predetermined first path, the scanning unit comprising:

a rail transverse to the first path;

a plurality of sources of beams of radiation supported by and movable across a second path transverse to the first path, along the rail; and

a detector positioned to detect radiation transmitted through a target during scanning.

66. The scanning unit of claim 65, wherein the second path extends partially around the first path, along the rail.

67. The scanning unit of claim 65, wherein the detector extends only partially around the first path.

68. The scanning unit of claim 65, wherein the detector is stationary.

69. The scanning unit of claim 65, wherein the plurality of sources are sources of X-ray radiation.

70. The scanning unit of claim 65, further comprising:

a transport system to transport the target along the first path.

71. The scanning unit of claim 65, wherein:

at least one of the plurality of sources generates radiation having an energy of at least 1 MeV.

72. The scanning unit of claim 65, further comprising:

means for transporting a cargo container along the first path;

wherein the plurality of sources and the detector are positioned so that the means for transporting can transport a cargo container along the first path, between the at least one of the one or more sources and the detector.

73. A scanning unit for examining an object, the scanning unit comprising:

means for transporting an object along a first path;

an arcuate rail transverse to the path;

one or more sources of radiation to irradiate the object, at least one of the one or more sources generating radiation having an energy of at least 1 MeV, being supported by the arcuate rail and being movable over at least a portion of a second path transverse to and only partially around the first path, along the rail;

a detector positioned to detect radiation transmitted through the object; and

a processor to reconstruct computed tomographic images based on the data collected by the detector, from radiation generated by the at least one of the one or more sources.

74. The scanning unit of claim 73, wherein:

the at least one of the one or more sources is mechanically movable over the at least a portion of the second path.

75. The scanning unit of claim 73, wherein:

the detector is stationary.

76. The scanning unit of claim 73, wherein:

the means for transporting is a means for transporting a cargo container; and

the at least one of the one or more sources and the detector are positioned so that the means for transporting can transport a cargo container along the first path between the at least one of the one or more sources and the detector.

77. The scanning unit of claim 73, wherein:

the arcuate rail is semi-circular; and

the second path is semi-circular.

78. A scanning unit for examining an object, the scanning unit comprising:

means for transporting an object along a first path;

an arcuate rail transverse to the first path;

one or more sources of radiation to irradiate the object, at least one of the one or more sources being mechanically movable over at least a portion of a second path transverse to the first path, along the arcuate rail, to irradiate the object; and

a detector positioned to detect radiation after interaction with the object, the detector extending only partially around the first path.

79. The scanning unit of claim 78, wherein the detector is stationary.

80. A scanning unit for examining an object, the scanning unit comprising:

means for transporting the object along a first path;

a semi-circular rail transverse to the first path;

a plurality of radiation sources to irradiate the object, at least two of the plurality of radiation sources being self-contained sources, each of the self-contained sources being movable over a portion of a second path, along the semi-circular rail; and

a detector positioned to detect radiation transmitted through the object during scanning.

81. The scanning unit of claim 80, wherein:

the self-contained radiation sources are chosen from a group consisting of a linear accelerator, an electrostatic accelerator, a microtron, a betatron, and an X-ray tube.

82. The scanning unit of claim 80, wherein each of the self-contained sources generate radiation of at least 1 MeV.

83. The scanning unit of claim 80, wherein the detector is stationary.

84. The scanning unit of claim 80, wherein:

the means for transporting is a means for transporting a cargo container; and

the at least one of the one or more sources and the detector are positioned so that the means for transporting can transport a cargo container along the first path, between the at least one of the one or more sources and the detector.

85. A scanning unit for examining a cargo container, the scanning unit comprising:

means for transporting a cargo container along a first path; and

one or more sources of radiation to irradiate the cargo container, at least one of the one or more sources being adapted to irradiate the cargo container with a cone beam of radiation, each of the at least one source of a cone beam of radiation being movable over a single, second path transverse to and at least partially around the first path; and

a stationary detector positioned to detect the cone beam of radiation after interaction with the cargo container;

wherein the at least one of the one or more sources and the detector are positioned so that the means for transporting can transport the cargo container along the first path, between the at least one of the one or more sources and the detector.

86. A scanning unit for examining contents of a cargo container, the scanning unit comprising:

means for transporting a cargo container through the system, along a first path;

an arcuate rail transverse to the first path;

one or more sources of radiation to irradiate the cargo container, at least one of the one or more sources being movable over a second path transverse to and only partially around the first path, along the rail; and

a detector positioned to detect radiation transmitted through the cargo container by the at least one of the one or more sources, to collect sufficient data for computed tomographic reconstruction;

wherein the at least one of the one or more sources and the detector are positioned so that the means for transporting can transport a cargo container between the at least one of the one or more sources and the detector.

87. The scanning unit of claim 86, wherein:

the at least one of the one or more sources generates radiation of at least 1 MeV.

88. The scanning unit of claim 86, wherein the at least one of the one or more sources are each linear accelerators.

89. The scanning unit of claim 86, wherein the at least one of the one or more sources generates a cone beam of radiation with which to irradiate the cargo container.

90. The scanning unit of claim 86, wherein:

the path extends over an arc of at least 180 degrees; and

the detector extends over an arc of at least 180 degrees.

91. The scanning unit of claim 86, wherein:

the at least one of the one or more sources emits a radiation beam having a lateral arc parallel to the second path;

the second path is arcuate;

the detector is arcuate; and

at least either the second path or the detector extends over an arc of at least 180 degrees plus the lateral arc of the radiation beam emitted by the at least one of the one or more sources, to obtain a complete data set for computed tomographic reconstruction.

92. The scanning unit of claim 86, wherein the detector is stationary.

93. The scanning unit of claim 86, wherein:

the at least one of the one or more sources is mechanically movable over the at least a portion of the second path.

94. The scanning unit of claim 86, wherein the cargo container has a height and/or width of at least 1.5 meters.

95. A method of examining contents of a cargo container, comprising:

providing one or more sources of radiation;

moving at least one of the one or more sources of radiation over at least a portion of a path extending only partially around a cargo container, along an arcuate rail;

scanning at least a portion of the cargo container with radiation from the at least one source;

detecting radiation transmitted through the cargo container, the detected radiation comprising sufficient data for computed tomographic reconstruction of at least a portion of the contents of the cargo container; and

processing data based on the detected radiation to form computed tomographic images of at least the portion of the contents of the cargo container based on the data.