X-ray tomography inspection systems

• US 8,135,110 B2
• Filed: 06/19/2008
• Issued: 03/13/2012
• Est. Priority Date: 12/16/2005
• Status: Active Grant

• Current Assignee: Rapiscan Systems Incorporated (OSI Systems Incorporated)
• Original Assignee: Rapiscan Systems Incorporated (OSI Systems Incorporated)
• Inventors: Morton, Edward James
• Primary Examiner(s): Glick, Edward
• Assistant Examiner(s): Artman, Thomas R
• Application Number:
  US12/142,005
• Publication Number:
  US 20090060135A1
• Time in Patent Office: 1,363 Days
• Field of Search: 378/6, 378/10, 378/57, 378/87
• US Class Current: 378/57
• CPC Class Codes: G01N 2223/3304 helicoidal scan
• CPC Class Codes: G01N 2223/3307 source and detector fixed; object moves
• CPC Class Codes: G01N 2223/3308 object translates
• CPC Class Codes: G01N 2223/401 image processing
• 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 2223/5015 linear array
• CPC Class Codes: G01N 2223/639 material in a container
• CPC Class Codes: G01N 2223/643 object on conveyor
• CPC Class Codes: G01N 23/046 using tomography, e.g. computed tomography [CT]
• CPC Class Codes: G01N 23/10 the material being confined in a container, e.g. in a luggage X-ray scanners
• CPC Class Codes: G01N 23/20083 by using a combination of at least two measurements at least one being a transmission measurement and one a scatter measurement
• CPC Class Codes: G01T 1/246 utilizing latent read-out, e.g. charge stored and read-out later
• CPC Class Codes: G01T 1/247 Detector read-out circuitry for processing gain or off-set correction H04N
• 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 5/22 Active interrogation, i.e. by irradiating objects or goods using external radiation sources, e.g. using gamma rays or cosmic rays
• CPC Class Codes: G01V 5/222 measuring scattered radiation
• CPC Class Codes: G01V 5/226 using tomography
• CPC Class Codes: G06T 7/12 Edge-based segmentation
• CPC Class Codes: G06T 7/143 involving probabilistic approaches, e.g. Markov random field [MRF] modelling
• CPC Class Codes: G06T 7/187 : involving region growing; involving region merging; involving connected component labelling

Abstract

The present invention is an X-ray scanning system with an X-ray source arranged to generate X-rays from X-ray source positions around a scanning region, a first set of detectors arranged to detect X-rays transmitted through the scanning region, a second set of detectors arranged to detect X-rays scattered within the scanning region, and a processor arranged to process outputs from the detectors to generate image data.

Claims

1. An X-ray scanning system for scanning an object comprising at least one X-ray source arranged to generate X-rays from a plurality of X-ray source positions around a scanning region wherein said X-ray sources do not move relative to said object during a scan, a first set of detectors arranged to detect X-rays transmitted through the scanning region wherein said first set of detectors is configured in a circular array defined by a first radius and wherein said circular array is positioned opposite said at least one X-ray source with an inspection volume defined therebetween, a second set of detectors arranged to detect X-rays scattered within the scanning region wherein the second set of detectors is arranged in at least one circular array having said first radius, wherein said circular array is positioned axially adjacent to said at least one X-ray source and on the same side of the inspection volume, wherein a collimator is positioned in front of the second set of detectors to collimate the X-rays scattered toward each of said second set of detectors, and wherein the collimator defines a receiving direction that is inclined relative to a plane defined by the detectors, and processing means arranged to process outputs from the first set of detectors to generate CT image data which defines an image of the scanning region, to analyze the CT image data to identify an object within the image, and to process the outputs from the second set of detectors to generate scattering data, and to associate parts of the scattering data with the object.

2. A system according to claim 1 wherein the processing means is arranged to determine from the scattering data a measure of the level of scattering from different positions within the scanning region.

3. A system according to claim 2 wherein the scattering is coherent scattering.

4. A system according to claim 3 wherein the processing means is arranged to determine, from the position of the detector that detects a scattered X-ray and the direction from which the X-ray was directed at the scanning region, the position at which the X-ray was scattered.

5. A system according to claim 1 wherein the scattering is incoherent scattering.

6. A system according to claim 1 wherein the processing means is arranged to determine from the CT image data an indication of a position at which the scattered X-rays may have been scattered.

7. A system according to claim 1 wherein the processing means is arranged define a plurality of pixels within the image, and to identify at least one of the pixels as being associated with the object, and to associate parts of the scattering data with respective pixels.

8. A system according to claim 1 wherein the two sets of detectors are on opposite sides of the source.

9. A system according to claim 1 wherein the first set of detectors are arranged in an arc defining an axis of the system.

10. A system according to claim 9 wherein the second set of detectors are arranged in a plurality of arcs around the system axis, the arcs being spaced along the axis.

11. A system according to claim 1 further comprising a data collecting system for collecting said scattering data and said CT image, wherein said data collecting system comprises a memory having a plurality of areas each being associated with a respective area of said image, data input means arranged to receive input data from a plurality of X-ray detectors in a predetermined sequence, at least one processor arranged to generate from the input data CT image data and scattering data associated with each of the areas of the image, and to store the CT image data and the scattering data in the appropriate memory areas.

12. A system according to claim 11 wherein the processor is arranged to determine which area any part of the CT image data or scattering data is to be associated with at least partly on the basis of which detector it is received from.

13. A system according to claim 11 wherein the processor is arranged to determine which area any part of the CT image data or scattering data is to be associated with, at least partly on the basis of the position at which the X-ray was produced.

14. A system according to claim 11 further comprising a look-up table having entries stored therein that associate each of the detectors with a respective area of the image.

15. A system according to claim 11 wherein the processor is arranged to store CT image and scattering data in the memory for each of a plurality of tomographic scans of an object as the object moves through an imaging region, and to extract the CT image data from the memory after each of the scans so that CT image data for a subsequent scan can be stored in the memory.

16. An X-ray imaging system according to claim 15 wherein the processor is arranged to combine the CT image data from the tomographic scans to produce a three-dimensional image of the object.