IMAGE RECONSTRUCTION METHOD AND SYSTEM

Abstract

A method of construction of a 3-dimensional image from the scanning of an object by penetrating radiation is described comprising: causing an object to pass through a static radiation field; rotating the object as it passes through the static radiation field; thereby successively collecting a plurality of scanned image slices as the object passes through the radiation field; using the image slices to form a 3-dimensional image. A scanning system for construction of a 3-dimensional image from the scanning of an object by penetrating radiation is also described comprising: an object scanner comprising a radiation generator to generate a static imaging radiation field and a radiation detector spaced therefrom to define an imaging zone; an object handler adapted to cause the object to move relative to and pass through the static imaging radiation field and simultaneously rotate the object as it passes through the static imaging radiation field; an image data collector to successively collect scanned image slices as the object passes through the imaging radiation field; an image data processor to process the image slices to form a 3-dimensional image.

Claims

1. A method of construction of a 3-dimensional image from the scanning of an object by penetrating radiation comprising: causing an object to pass through a static radiation field; rotating the object as it passes through the static radiation field; thereby successively collecting a plurality of scanned image slices as the object passes through the radiation field; and using the image slices to form a 3-dimensional image.

2. A method in accordance with claim 1 comprising: causing an object to be translated in a longitudinal direction through a two dimensional field of penetrating radiation; causing an object to rotate at an axis parallel to the longitudinal direction as it is translated through the two dimensional field of penetrating radiation; detecting at a suitable detection system the radiation transmitted through the object as it is translated through the two dimensional field of penetrating radiation; thereby collecting a successive plurality of scanned image slices as the object passes through the imaging radiation field; and using the image slices to construct a 3-dimensional image.

3. A method in accordance with claim 1 wherein the penetrating radiation is x-ray radiation.

4. A scanning system for construction of a 3-dimensional image from the scanning of an object by penetrating radiation comprising: an object scanner comprising a radiation generator to generate a static imaging radiation field and a radiation detector spaced therefrom to define an imaging zone; an object handler adapted to cause the object to move relative to and pass through the static imaging radiation field and simultaneously rotate the object as it passes through the static imaging radiation field; an image data collector to successively collect scanned image slices as the object passes through the imaging radiation field; and an image data processor to process the image slices to form a 3-dimensional image.

5. A scanning system in accordance with claim 4 wherein: the object scanner comprises a radiation generator that generates a static two dimensional field of penetrating radiation; the object handler that causes an object to be translated in a longitudinal direction through the two dimensional field of penetrating radiation, and simultaneously causes an object to rotate about an axis parallel to the longitudinal direction as it is translated through the two dimensional field of penetrating radiation.

6. A scanning system in accordance with claim 4 wherein the radiation generator is a source of x-rays and the radiation detector is a detector of x-rays.

7. A scanning system in accordance with claim 4 comprising a radiation generator for generating a two dimensional field of penetrating radiation, and a radiation detection system comprising at least one radiation detector spaced remotely therefrom and positioned to collect the radiation transmitted through an object in the imaging radiation field.

8. A scanning system in accordance with claim 7 wherein the radiation generator and radiation detection system are held in fixed spatial relationship to each other and may be statically supported for example on a suitable support body.

9. A scanning system in accordance with claim 4 wherein the object handler is mounted in association with the radiation generator and radiation detection system in such configuration that an object handled thereby may be translated and rotated relative to the radiation generator and radiation detection system, and in particular translated through the imaging radiation field and simultaneously rotated.

10. A method in accordance with claim 1 wherein the detector comprises an L-shaped radiation detector array.

11. A method in accordance with claim 1 comprising matching the lateral speed to the speed of rotation of the object.

12. A method in accordance with claim 1 comprising collecting data regarding the intensity of transmitted radiation after interaction with an object in the imaging radiation field and the data regarding the intensity of transmitted radiation is processed at the detector.

13. A method in accordance with claim 1 a scanning system comprises collecting a successive plurality of scanned image slices as the object passes through the imaging radiation field and the image slices are used to construct one or more 3-dimensional images of the object as it passes through the imaging radiation field.

14. A method in accordance with claim 13 further comprising the additional step of displaying such image or images.

15. A method in accordance with claim 1 employed as a method of detecting unauthorised materials within portable electronic devices.

Description

[0046] The invention will now be described by way of example only with reference to the accompanying drawings in which:

[0047] FIG. 1 shows a general layout of a conventional x-ray system, with a single static field of view;

[0048] FIG. 2 shows a detector array such as that shown in FIG. 1 adapted to be used as a system and perform a method in accordance with the principles of the invention;

[0049] FIG. 3 is a simple flow chart schematic of an arrangement including the detector of FIG. 2 in a more complete system and in performing a method in accordance with the principles of the invention.

[0050] The general layout of a conventional x-ray system, with only a single static field of view shown for clarity, is reproduced as FIG. 1. In the example embodiment the system has a rectangular scanning tunnel (1) in which an object under test is scanned. The object under test is caused to move along a linear translational direction (D) by being carried on a belt conveyor (3). The object is therefore caused to pass through a radiation field in a scanning zone (S) of a scanning device within the tunnel (1). Imaging information may be generated as the object under test passes through the radiation field.

[0051] The scanning device has a generator comprising an x-ray source (5) mounted some distance from a detector array (7) that covers the two opposing tunnel sides of the system. This is generally known as an L shaped array. Certain system iterations may have more than one generator. Practical systems may have multiple fields of view but only one is shown for clarity.

[0052] FIG. 2 shows how that L shaped array may be used with an associated electro-mechanical motion system embodying the principle of the invention that rotates the item being scanned around a longitudinal axis, whilst passing it through the x-ray beam.

[0053] As in the example in FIG. 1, a rectangular scanning tunnel (11) is provided in which an object under test is scanned. The scanning device has a generator comprising an x-ray source (15) and an L-shaped detector array (17) that covers the two opposing tunnel sides of the system. A scanning zone is again defined between the x-ray source (15) and an L-shaped detector array (17). The x-ray source and L-shaped detector array are static and define a static radiation field in the scanning zone.

[0054] The object under test (21) is caused to move along a linear translational direction (D) by being carried by an electro-mechanical motion system including a handling arm (19). The handling arm causes the object (21) to move along a linear translational direction (D) and thereby pass through the radiation field in the scanning zone.

[0055] However, the electro-mechanical motion system is adapted additionally to cause the object under test to rotate about the rotation axis (23) in direction R as it moves laterally through the static imaging radiation field. Matching the lateral speed to the speed of rotation allows for as many views as necessary to be take, slice by slice, as the object to be scanned passes through the beam from the x-ray source.

[0056] Multiple views and multiple image slices are thus obtained for further processing in a manner analogous to a conventional CT scanner, but in accordance with the principles of the invention using a static scanning system and in the particular case of the embodiment a single two dimensional static field of view. Multiple image slices from multiple effective views are generated not by movement of the scanning system but by the progressive and simultaneous translation and rotation of the object through this static field of view.

[0057] The successive image slices may be co-operably processed and cross correlated to form a voxelated image by a suitable image processing method in analogous manner to that used for multiple slices produced by a conventional CT scanner. However, the apparatus required to collect the multiple slices is a simple single view static scanner, and the apparatus and method therefore offer significant advantages of ease of processing and cost of equipment over conventional CT scanners.

[0058] An image data processor, which may for example be a processor of a suitably programmed general purpose or special purpose computer may be provided to process the image slices to form a 3-dimensional image. Optional image display means may be provided.

[0059] FIG. 3 is a simple flow chart schematic of an arrangement including the detector of FIG. 2 in a more complete system.

[0060] An image data processing module receives the collected intensity data image slices from the L-shaped detector via a suitable data connection and processes these to create a 3-dimensional image in accordance with the principles of the invention, where the step of creation of a 3-dimensional image will be understood to encompass the creation of an information dataset, for example in the form of a suitable stored and manipulatable data file, from which a visual 3-dimensional representation of the underlying structure of the object under investigation could be produced but not to require that image information dataset to be presented as a viewable or viewed visible image as such.

[0061] This image information dataset may then optionally be output via a further suitable data connection to the visual display module which includes a display screen on which it produces such a viewable visible image.