GB2552535A

GB2552535A - Detection of scatter radiation

Info

Publication number: GB2552535A
Application number: GB1613065.0A
Authority: GB
Inventors: Jegou Guillaume
Original assignee: Smiths Heimann SAS
Current assignee: Smiths Heimann SAS
Priority date: 2016-07-28
Filing date: 2016-07-28
Publication date: 2018-01-31
Anticipated expiration: 2036-07-28
Also published as: GB2552535B; GB201613065D0

Abstract

A detection system comprises a matrix of detectors 2, each detector configured to detect radiation scattered by an associate portion of a load 8 to be inspected, the radiation being scattered in response to the respective portion of the load being irradiated by radiation transmitted through the portion. The system further comprises a selection device 11 configured to, for each detector of the matrix, limit the scattered radiation incident on a detector to that scattered by its associated portion only. Each portion of the load may correspond to a voxel of the load or a pixel of an image generated using data from the matrix. The selection device may comprise a block 4 (e.g., of lead) and an aperture 12 through which radiation may pass. The radiation be emitted at a source 1 and may be X-rays, gamma rays, or neutron radiation. The system may further comprise a detector 5 of radiation transmitted through the load.

Description

(56) Documents Cited:

(71) Applicant(s):

Smiths Heimann SAS

Rue Charles Heller, Vitry-Sur-Seine, 94400,

France (including Overseas Departments and Territori es) (72) Inventor(s):

Guillaume Jegou

WO 2014/045045 A1 WO 1998/020366 A1 US 20140241494 A1 US 20100034347 A1 (58) Field of Search:

INT CL G01N, G01V Other: EPODOC and WPI

WO 2001/084183 A2 US 20160033427 A1 US 20120207271 A US 20040174959 A1 (74) Agent and/or Address for Service:

Mathys & Squire LLP

The Shard, 32 London Bridge Street, LONDON, SE1 9SG, United Kingdom (54) Title of the Invention: Detection of scatter radiation

Abstract Title: Load inspection system with matrix detector of scattered radiation and selection device to limit field of view of each detector (57) A detection system comprises a matrix of detectors 2, each detector configured to detect radiation scattered by an associate portion of a load 8 to be inspected, the radiation being scattered in response to the respective portion of the load being irradiated by radiation transmitted through the portion. The system further comprises a selection device 11 configured to, for each detector of the matrix, limit the scattered radiation incident on a detector to that scattered by its associated portion only. Each portion of the load may correspond to a voxel of the load or a pixel of an image generated using data from the matrix. The selection device may comprise a block 4 (e.g., of lead) and an aperture 12 through which radiation may pass. The radiation be emitted at a source 1 and may be X-rays, gamma rays, or neutron radiation. The system may further comprise a detector 5 of radiation transmitted through the load.

Figure 1

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Figure 1

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Figure 2

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Figure 4 x

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Figure 5B

Figure 6

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100

Figure 7

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Figure 8

Detection of scatter radiation

Field of Invention

The present disclosure relates, but is not limited, to systems and methods for inspecting a 5 load with a source of radiation.

Background

Inspection systems use inspection radiation through e.g. vehicles for inspecting cargo of the vehicle, for example to detect hidden objects (such as weapons or dangerous material).

However objects placed in the line of transmission of opaque materials and/or which appear 10 dark on the view by transmission are difficult to detect on a view by transmission. A user may for example fail to detect some objects in X-ray images, because of overlaps and/or their location in the line of transmission of low transmission objects.

Aspects of the present invention address some of the above issues.

Summary of Invention

Aspects and embodiments of the invention are set out in the appended claims. These and other aspects and embodiments of the invention are also described herein.

Presentation of the Figures

Embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a schematic illustration in perspective of a load being irradiated and radiation scattered by the load passing through an aperture to a detector;

Figure 2 shows a schematic illustration of scatter radiation passing through the aperture of Figure 1;

Figure 3 shows a schematic elevation illustration of a first zone of a load being irradiated and 25 radiation scattered by the first zone passing through an aperture to a detector;

Figure 4 shows a schematic elevation illustration of a second zone of the load of Figure 3 being irradiated and radiation scattered by the second zone passing through an aperture to a detector;

Figure 5A shows a fan beam irradiating a zone of a load;

Figure 5B shows an example apparatus irradiating a zone of a load with a fan beam;

Figure 6 shows a schematic illustration of a load that has been irradiated in zones;

Figure 7 shows an example system positioned at a distance from, and forming an angle with, an inspection direction of the load; and

Figure 8 shows a flowchart which illustrates an example method for inspecting a load.

In the drawings, like elements are referred to by the same numerical references.

Description of Example Embodiments

Overview

Embodiments of the present disclosure relate to a detection system for inspection of a load.

The system comprises a matrix of detectors to detect scatter radiation from the load, in order to allow one or more properties of the load to be determined. The scatter radiation is emitted by a zone of the load in response to the zone being irradiated by radiation transmitted through the zone. The irradiated zone comprises respective portions, each respective portion corresponding for example to a voxel of the zone. The system further comprises a selection device configured to enable radiation scattered by a respective portion of the load to reach an associated detector on the matrix. The selection device inhibits any other scatter radiation to reach the associated detector. Each of the detectors of the matrix is associated with a respective portion of the load and may correspond for example to a pixel of a 2dimensional (2D) image of the zone, generated from data associated with the matrix of detectors. In some examples, the 2D image of the zone may be referred to as a 2D slice (or cross section) of the load.

In examples where the load is moved with respect to the detection system in an inspection direction, the system may enable a 3-dimensional (3D) image of the load to be obtained, e.g. by grouping the 2D images of the zone in a direction corresponding to the inspection direction. The 3D image of the load may enable an enhanced detection of hidden objects.

Detailed Description of Example Embodiments

As illustrated in the Figures, the system may be described with reference to an orthonormal reference OXYZ, axis (Oz) being the ascending vertical, a plane YOZ being vertical, a plane XOY being horizontal, and a plane XOZ being vertical.

In the example of Figure 1, a detection system 100 comprises a matrix 2 of detectors (some detectors are referred to as e.g. detector 14, 15 or 16 in Figure 1) and a selection device 11 comprising an aperture 12.

Each detector 14, 15 or 16 of the matrix 2 of detectors is configured to detect radiation 23 scattered by an associated respective portion (e.g. some portions are referred to as e.g. portion 18, 19 or 20, respectively, in Figure 1) of a load 8 to inspect. The radiation 23 is scattered in response to the respective portion 18, 19 or 20 being irradiated by radiation 22 transmitted through the portion 18, 19 or 20, respectively. As explained in greater detail below, in some examples the radiation 22 may comprise X-ray radiation and the detectors (e.g. the detectors 14, 15 and 16) of the matrix 2 may comprise, amongst other conventional electrical elements, X-ray detection detectors. Each of the X-ray detection detectors may be configured to measure an amplitude of a signal in a scintillator.

Each ray of the scatter radiation 23 is emitted by the respective portion 18, 19 or 20, respectively, when the radiation 22 irradiates the portion 18, 19 or 20 of the load 8 (for example because of Compton scattering and pair production in the case of X-ray and/or gamma radiation). The scatter radiation 23 is emitted in all the directions.

As illustrated in Figure 1, a zone 6 of the load 8 (the zone 6 comprising the respective portions 18, 19 or 20 in Figure 1) is irradiated by the radiation 22. The zone 6 of the load 8, upon being irradiated, emits the scatter radiation 23. In the example of Figure 1, the respective portions 18, 19 and 20 are located in the zone 6, and each respective portion 18, 19 or 20 emits the scatter radiation 23 in a number of example directions. It should be understood that in a system 100 not comprising the selection device 11 according to the disclosure, the scatter radiation 23 emitted in all of the directions, by all of the respective portions (e.g. the portions 18, 19 and 20) of the zone 6, would be detected by each one of the detectors (e.g. the detectors 14, 15 and 16) of the matrix 2. Imaging of the zone 6 using data collected by the matrix 2 would not be possible.

In the example of Figure 1, the aperture 12 of the selection device 11 is configured to enable radiation 26, 30b and 28b, scattered respectively by the respective portions 18, 19 and 20 of the zone 6 of the load 8, to reach the respective detectors 14, 15 and 16 of the matrix 2 of detectors. In the example of Figure 1 the portion 18 is associated with the detector 14, because the detector 14 is in the line of sight of the portion 18 through the aperture 12 (i.e. the detector 14, the aperture 12 and the portion 18 are aligned), the portion 19 is associated with the detector 15, because the detector 15 is in the line of sight of the portion 19 through the aperture 12 (i.e. the detector 15, the aperture 12 and the portion 19 are aligned), and the portion 20 is associated with the detector 16, because the detector 16 is in the line of sight of the portion 20 through the aperture 12 (i.e. the detector 16, the aperture 12 and the portion 20 are aligned).

In the example of Figure 1 the scatter radiation 26, 30b or 28b corresponds, respectively, to the line of sight between the respective portion 18, 19 or 20 and the respective detector 14, 15 or 16, and is thus enabled to pass through the selection device 11 via the aperture 2.

Figure 2 (not to scale) provides an illustration of a detail of the detection system 100 of Figure 1, in which the respective portion 20 of Figure 1 is emitting the scatter radiation 23 in example directions, such as directions referred to as 28a, 28b, 28c, 28d, 28e and 28f. In the example shown in Figure 2, the scatter radiation 23 from the respective portion 19 of Figure 1 is also emitting the scatter radiation 23 in example directions, such as directions referred to as 30a, 30b, 30c, 30d, 30e and 30f.

It should be understood that Figure 2 is a simplified image showing a selection of rays of the scatter radiation 23 emitted by only two respective portions 19 and 20 of the zone 6 of Figure 1. The number of respective portions and the scatter radiation emitted by each respective portion has been limited for illustrative purposes.

In the example of Figure 2, the radiation emitted from the portion 20 in the direction 28b passes through the aperture 12 to reach the associated detector 16 of the matrix 2 of detectors. Similarly, the scatter radiation from the portion 19 in the direction 30b passes through the aperture 12 to reach the associated detector 15 of the matrix 2 of detectors.

The scatter radiation 23 emitted by the portion 19 is prevented from reaching the detector 16, because the portion 19 is not in the line of sight of the detector 16 (the detector 16 is not associated with the portion 19). The scatter radiation 23 emitted by the portion 20 is prevented from reaching the detector 15, because the portion 20 is not in the line of sight of the detector 15 (the detector 15 is not associated with the portion 20).

In the example of Figure 2, the scatter radiation 23 emitted by the portion 20 in other directions (in this illustration radiation emitted e.g. in directions 28a, 28c, 28d, 28e and 28f) is also inhibited from passing through the aperture 12 to reach the detector 16 (and also the other detectors). The scatter radiation 23 emitted by the portion 19 in the directions 30a, 30c,

30d, 30e and 30f is inhibited from passing through the aperture 12 to reach the detector 15 (and also the other detectors).

The aperture 12 is thus configured to allow the radiation 23 scattered from a respective portion and in a certain direction, associated with a detector, to pass through the aperture 12 to reach the associated detector. The radiation scattered by the respective portion in other directions and the radiation scattered by other respective portions are prevented from passing through the aperture 12 to the reach the detector associated with the respective portion.

In some examples, the device 11 may comprise a block 4 and the aperture 12 may comprise a hole 17, the hole 17 being located in the block 4.

In some examples, the block 4 comprises a material that inhibits the scatter radiation from reaching the matrix 2. For example the block 4 may be made from a material (e.g., lead) that blocks or at least attenuates radiation, and therefore prevents radiation from reaching the matrix 2. In the example described above, the hole 17 may comprise an area without any material, to allow the desired scatter radiation to pass through the aperture 12 to reach the matrix 2. In such an example radiation that is able to pass through the hole 17 is not attenuated when passing through the hole 17.

In some examples, the aperture 12 may comprise a filter. In some examples a filter may enable reduction of noise.

In the example of Figure 1, dimensions e and E of the aperture 12 of the device 11 are dependent on a distance L1 between the zone 6 and the device 11, and/or on a distance L2 between the matrix 2 and the device 11, and/or dimensions of the load to inspect.

In some examples, the dimensions e and E are predetermined such that:

each respective portion (such as the portion 18, 19 or 20) corresponds to a voxel of the zone 6 of the load 8 (e.g. as viewed from the detectors such as the detector 14, 15 or 16), and/or each respective detector (such as the detector 14, 15 or 16) associated with a respective portion detects the radiation scattered from the single voxel formed by the respective portion - each respective detector corresponds to a pixel of the matrix 2 viewed from the respective portion.

The selection device 11 enables imaging of the zone 6, using detection of the scatter radiation 23, because each one of the detectors of the matrix 2 is configured to be targeted by a unique voxel of the zone 6 and is configured to correspond to a pixel of a final 2D image of the zone 6. The final 2D image may be generated based on data collected by the detectors of the matrix 2.

In some examples, L1 may be greater than 1m. In such examples, the system 100 may enable reduced noise (and may also avoid intersecting an inspection direction INS as described in greater detail below). In some examples, the matrix 2 may be relatively close to the load 8 and get a relatively large amount of scatter radiation 23. In some examples, L1 and L2 are such that L1+L2<5m.

In some examples, L1 and L2 are such that L2<L1. In such examples, the matrix is smaller than a load slice and is relatively not as expensive as a matrix larger than a slice.

In some examples, L1 and L2 are such that:

lm < LI < 5m, typically e.g. 2m; and

0.3m <L2<5m, typically e.g. 1m.

In some examples, e is equal to E, but any form ratio can be chosen for the aperture 12, e.g. depending on a form ratio of the load and/or the detectors of the matrix 2.

E and e may depend on dimensions of the detectors (e.g. pixel size) of the matrix 2. In examples E and e may have dimensions about half of the size of the detectors of the matrix 2. For example, for a slice of the load 8 having dimensions 5mx3m in a plane parallel to the (YOZ) plane (e.g. a cross section of the load), the matrix 2 may comprise 500x300 detectors (corresponding to a 500x300 resolution). In examples where L1=2m and L2=1m, the pixel size may be 5mmx5mm. In examples E and e may be such that E=2.5mm and e=2.5mm.

In some examples the device 11 may act as a diaphragm (e.g. a hole collimator). In the examples described above, the aperture 12 has a regular parallelepiped shape. It should be understood that, alternatively or additionally, the aperture 12 may have a truncated pyramid shape, with E and e dimensions being located at the truncated apex.

It should also be understood that the above dimensions are example dimensions for loads comprising e.g. vehicles and/or ISO containers. Other dimensions are envisaged, e.g. for applications including inspection of luggage.

Dimensions of the matrix 2 of detectors may be selected based on dimensions of the load to inspect. For example, the matrix 2 of detectors may have a ratio of dimensions (such as a height to width ratio) that is based on (e.g. smaller than or equal to) a ratio of dimensions (such as a height to width ratio) of the load. As described in greater detail below, in some examples the load 8 may have a size that corresponds to a standard size, and the matrix 2 of detectors may have a ratio of dimensions corresponding to that standard size (such as an ISO container).

Alternatively or additionally, the dimensions of the matrix of detectors may be dependent upon the distances L1 and/or L2. For example, a greater distance L2 between the aperture 12 and the matrix 2 of detectors may lead to a larger projection of the load onto the matrix of detectors (a relatively larger matrix of detectors may be required). Similarly a greater distance L1 between the aperture 12 and the load 8 may lead to a smaller projection of the load 8 onto the matrix 2 of detectors (a relatively smaller matrix of detectors may be required).

In some examples, the matrix may have dimensions corresponding to dimensions of a cross section of the load, multiplied by a L2/L1 ratio. In some examples, the matrix may have dimensions such that 2.5m x 1.5m. In some examples, L2 may be reduced and the matrix may have smaller dimensions and be relatively less expensive.

Other dimensions and distances are envisaged.

In the example of Figure 1, the radiation 22 is emitted by a source 1.

In the example of Figure 1, the radiation 22 is configured to be transmitted through the load 8. In the example of Figure 1, the radiation 22 is shown as a collimated almost parallel beam irradiating the load 8 in a direction parallel to the (Oz) axis. However, other forms of beams are envisaged for the radiation 22, and other directions of irradiations are also envisaged. In some examples, the source 1 may be configured to irradiate the load 8 using a fan beam. An example of a fan beam is illustrated in Figure 5A and has an angular width β such that the load 8 may be irradiated across its width in a direction both parallel to the axis (Oy) and perpendicular to an inspection direction INS, parallel to the axis (Ox). In other examples, the load 8 may be irradiated by other types of beams, such as a pencil beam. In the example of Figure 5B, the load 8 is irradiated by a fan beam in the YOZ plane, in a direction having an angle with respect to the (Oy) axis and the (Oz) axis.

In some examples, the source 1 may be configured to emit the radiation 22 for inspection of the load 8 by scatter radiation only. Alternatively or additionally, in some examples, and as illustrated e.g. in Figure 1 and Figure 5B, the source 1 may emit the radiation 22 for inspection of the load 8 by transmission of the radiation 22 through the load 8. In such examples apparatus 1000 comprising the system 100 may further comprise an additional detector 5 to detect the radiation 22 that has been transmitted through the load 8. The additional detector 5 may comprise, amongst other conventional electrical elements, radiation detection lines, such as X-ray detection lines.

In the example of Figure 1, shielding 7 is located between the source 1 and the matrix 2 of the system 100 and is configured to inhibit the radiation 22 from the source 1 from reaching the matrix 2, as in some examples the matrix 2 should detect the scatter radiation 23 only. The shielding 7 is configured to inhibit (e.g. block or at least attenuate) the radiation 22. The shielding 7 may comprise lead, but other materials are envisaged. The shielding 7 may form part of the apparatus 1000 external to the system 100, but in some examples the shielding may form part of the system 100.

In the example of Figure 1, shielding 7 is also located between the additional detector 5 and the matrix 2 of the system 100 and is configured to inhibit radiation 24 scattered by the additional detector 5 from reaching the matrix 2, as in some examples the matrix 2 should detect the scatter radiation 23 only.

In some examples, the detection system 100 is movable with respect to the load 8. In some examples, the detection system 100 may remain static with respect to the ground and the load 8 is moved with respect to the ground in an inspection direction INS (e.g. parallel to the (Ox) axis on the Figures). The above mode of operation is sometimes referred to as a “passthrough” mode of operation. Examples of pass-through modes of operation include the load being a vehicle such as a truck. In some examples, a driver of the vehicle may drive the truck through the detection system 100, e.g. including a gantry. In some examples (e.g. where the radiation is relatively high), the apparatus 1000 may comprise a conveyor configured to carry the vehicle (such as the truck) through the system 100, e.g. at low speed (e.g. lower than 5km/h). The above mode of operation is sometimes referred to as a “conveyor” mode of operation. Alternatively or additionally, the load 8 may remain static with respect to the ground and the detection system 100 may be moved with respect to the ground in the inspection direction. This mode of operation is sometimes referred to as a “scan” mode of operation.

Figures 3 and 4 show that the movement of the load 8 with respect to system 100 allows successive zones, e.g. zones 6 and 10, of the load 8 to be irradiated by the radiation 22 and therefore successively emit the scatter irradiation 23.

Figure 3 and Figure 4 illustrate an example of the detection system 100 of Figure 1 in which the load 8 is moved with respect to the detection system 100, e.g. in the inspection direction INS parallel to the axis (Ox).

Figure 3 shows the zone 6 of the load 8 being irradiated by the radiation 22. It should be understood that in some examples several (e.g. all of the) portions of the zone 6 may emit scatter radiation in response to being irradiated. However only the respective portions 18 and 20 (also shown in Figure 1) are represented in Figure 3, for the sake of clarity. The aperture 12 is configured to enable the radiation 28b scattered by the portion 20 to reach the associated detector 16 of the matrix 2 of detectors, and the radiation 26 scattered by the respective portion 18 of the load 8 to reach the associated detector 14 of the matrix 2 of detectors. A 2D image of the zone 6 (e.g. a first 2D slice of the load in a plane parallel to the (YOZ) plane) may be obtained.

In some examples, an analyser 3 may be configured to receive data from the matrix 2 (and/or the additional detector 5 when present) to generate one or more images, such as the 2D slice. The analyser 3 conventionally comprises at least a processor and a memory. In some examples, the analyser 3 may form part of the apparatus 1000 external to the system 100 or may form part of the system 100.

Figure 4 shows an example where the load 8 has moved in the inspection direction INS with respect to the detection system 100 and with respect to the position of the load 8 illustrated in Figure 3. In this example, the load 8 is irradiated by the radiation 22 such that the zone 10 of the load 8 is irradiated and emits scatter radiation. In the example shown in Figures 3 and 4, the load 8 has moved relative to the detection system 100 but the distances between the zone 6 or 10 being irradiated, the aperture 12 and the matrix 2 of detectors are the same both in Figure 3 and in Figure 4. Similarly to what has been described above with reference to the zone 6, a 2D image of the zone 10 (e.g. a second 2D slice of the load in a plane parallel to the (YOZ) plane) may be obtained.

It should be understood that in examples where the whole of the load is moved along the inspection direction INS and irradiated by the radiation 22, a 3D image of the load may be obtained, e.g. by combining all the obtained slices.

It should be understood that in some examples the 2D slices:

may overlap each other if the speed of the load is low compared to a frequency of irradiation of the load and/or of detection by the matrix, or may be slightly separated from each other if the speed of the load is higher than a frequency of irradiation of the load and/or of detection by the matrix.

In some examples, the analyser 3 may perform, at least partly, the combining of the slices to obtain the final 3D image.

As explained in greater detail below, the scatter radiation 23 emitted by a respective portion and/or a zone of the load 8 may be attenuated and/or affected by another portion and/or another zone of the load 8. In some examples the attenuation and/or impact of each of the other portions and/or zones of the load on the scatter radiation emitted by a current portion and/or zone may be dependent upon at least one property of other portions and/or zones of the loads, such as a material of the other portions and/or zones and/or an object located in the other portions and/or zones.

In some examples, the scatter radiation 23 emitted by a second zone (e.g. the current zone 10 in Figure 4) may be attenuated and/or affected by a first zone (e.g. the preceding zone 6 in Figure 4) prior to being received by the matrix 2. Therefore the magnitude of and/or the data associated with the scatter radiation may not be totally representative of the second zone 10 only. For example, the first zone 6 of the load 8 (located between the second zone 10 of the load 8 emitting the scatter radiation 23 and the matrix 2) may be highly attenuating and/or may comprise an object which could affect the radiation emitted by the current zone 10. When the scatter radiation 23 passes towards the matrix 2, it passes through the first zone 6 of the load 8 and may therefore be attenuated or affected.

Figure 6 shows an example in which the load 8 is irradiated in successive zones 34, 36, 38, 40, 42, 44, 46, 48, 50. In the example of Figure 6, the matrix 2 is located such that the zone 34 is closest to the matrix 2 and the zone 50 is furthest from the matrix 2. Radiation 23 scattered from the load 8 when the zone 34 is irradiated will therefore pass directly to the matrix 2 and will not pass through any other zones of the load 8, whereas radiation 23 scattered by the zone 50 will pass through the zones 34, 36, 38, 40, 42, 44, 46 and 48 before reaching the matrix 2. The scatter radiation emitted by the zone 50 will be attenuated and/or affected by the zones 34, 36, 38, 40, 42, 44, 46 and 48.

In some examples, the analyser 3 may be configured to process current data associated with the current zone (e.g. emitting scattered radiation because currently irradiated), to take into account one of the properties of the other zones of the load. In some examples and as explained above, the other zones may be the zones located between the current zone and the detection device 100.

In some examples the property of the other zones may be predetermined (e.g. measured by transmission). Alternatively or additionally, the other zones may correspond to zones which have previously emitted scatter radiation because they have been previously irradiated, and the property of the other zones may be have been previously detected using the detection system 100.

In some examples, the processing may take into account the property of the preceding zones by subtracting (e.g. accounting for impact by the preceding zones) and/or adding (e.g. accounting for attenuation by the preceding zones), from and/or to current data associated with the current zone, data corresponding to the preceding zones, in order to correct the current data to obtain more accurate information about the current zone.

In the developments above, the radiation scattered from a current zone may be attenuated and/or affected by another zone, i.e. in a direction parallel to the (Ox) axis in Figure 6.

It should be understood that, similarly, the radiation scattered by a respective portion may be attenuated and/or affected by another respective portion, i.e. in a direction parallel to the (YOZ) plane in Figures 1 and 6. Current data associated with a respective portion of the load emitting scattered radiation (e.g. portion 20 in Figure 1) may be affected by at least one property of another portion located in the plane parallel to the direction of transmission of the radiation 22 (e.g. the portion 18 in Figure 1). Alternatively or additionally the processing performed by the analyser 3 may take into account the property of e.g. the portion 18 to correct the current data from e.g. the portion 20, to obtain more accurate information about the current portion 20.

The amount of radiation scattered by a portion of the load decreases as the radiation irradiating the portion is attenuated (e.g. an X-ray flux of radiation 22 diminishes). In some examples, the X-ray incident flux diminishes with a coefficient in d², where d is the distance to a focal spot of the source 1. Alternatively or additionally, the analyser 3 is configured to process the current data associated with a current respective portion of the load emitting scattered radiation, to take into account a distance of the portion from the source of radiation, e.g. by applying a correcting coefficient based on the above coefficient in d².

Alternatively or additionally, in some examples, the analyser 3 may be configured to estimate a nature of a material of the load, based on a detection of a level of scattered radiation 23 and/or on a spectrum of energy of the scattered radiation by the matrix 2.

The level of scattered radiation 23 may be dependent upon the material producing the scatter radiation. Materials having a low Z number (like plastic or water) produce more scatter radiation 23 than materials having a high Z number (like lead or gold). A relatively high level of scattered radiation detected by the matrix 2 may enable estimation that the irradiated zone comprises an organic material, whereas a relatively low level of scattered radiation detected by the matrix 2 may enable estimation that the irradiated zone comprises a non-organic material. The system 100 may therefore enable estimation of what type of material is present in the load, based on the detected level of scatter radiation and/or based on a level of scatter photon energy distribution, which may also vary with the material present in the load. In an example, the system 100 may enable enhanced detection of hidden objects and/or certain materials (i.e. explosives) present in the load.

In the examples described above, the load 8 is irradiated from one direction by a single source 1 of radiation 22. It should be understood that more than one radiation source may also be used, and the apparatus 1000 may thus comprise a plurality of sources 1. For example the load may be irradiated from more than one direction, from more than a source of radiation. As explained above, scatter radiation:

may have a greater level nearer a source of radiation, because the irradiating radiation has a greater flux; and/or may be more attenuated and/or affected by one or more properties of other portions as the irradiating radiation travels in the load away from the source.

In some examples, irradiating the load by more than one source may enhance a quality of data corresponding to detected scatter radiation, e.g. detected nearer the respective source. In some examples, the scatter radiation from one or more sources 1 may be detected by a single detection system 100.

The system 100 described above may be used in the apparatus 1000 which may also comprise the source 1. In some examples the apparatus may comprise a plurality of systems 100 according to any aspect of the disclosure, each of the system 100 comprising a selection device and a matrix.

In some examples, a plurality of views of the load may be obtained using the plurality of systems (and one source or a plurality of sources of radiation). It should be understood that each system 100 may generate a view and hidden objects may be detected using the plurality of views. The one or more systems may be placed at different given positions in the apparatus, depending on the desired views. The one or more sources of radiation may be placed at different given positions in the apparatus, depending on the desired views.

In the examples illustrated above, the system 100 is positioned on the inspection direction INS. The above configuration of the system 100 enables a 2D slice to be generated in a plane parallel to the plane (YOZ) using data detected by the matrix 2, without any parallax. In other words, the detection system 100 defines a main direction D (shown in Figure 1) of detection which is parallel to the inspection direction INS (and e.g. perpendicular to a main plane of irradiation of the load which is parallel to the (YOZ) plane).

The above configuration of the system 100 may be used, e.g. for relatively small loads. It should be understood that in the above configuration, the system 100 is positioned on the inspection direction INS, and prevents the system 100 from operating in a full pass-through mode and/or from inspecting relatively large loads, as the system 100 is in the way of the load 8.

In examples where the detection system 100 needs to operate in a full pass-through and/or conveyor mode, or where relatively large loads need to be inspected, the system 100 is not located on the inspection direction INS to enable the load 8 to move along the inspection direction INS. In such examples, and as illustrated in Figure 7, the system 100 may be positioned at a minimum distance h from the inspection direction INS and enables the load 8 to travel on the inspection direction INS without intersecting the detection system 100. The main direction of detection D of the system 100 may form an angle a with respect to the inspection direction INS.

In the example of Figure 7, because of the distance h and/or the angle a relative to the inspection direction INS, the final image generated by data obtained by the detection system 100 may be distorted. It can be seen on Figure 7 that the distortion is created when e.g. the radiation 23 scattered by the portion 18 is received by the matrix 2 at an angle that is different from the angle at which the radiation 23 scattered by the portion 20. The distorted final image of the slices may lead to a distorted image of the load.

In some examples, the analyser 3 may be further configured to compensate for the distortion based on the values of h and a, as the distance h and the angle a are known for a given detection system 100.

In the examples described above, the matrix may be square or rectangular. Alternatively or additionally, in some examples the matrix 2 may have trapezoid shape based the above values of h and a.

In some embodiments and as shown in Figure 8, a method for inspecting one or more loads 8 comprises:

selecting, at S2, radiation scattered by each respective portion of a load to inspect, the radiation being scattered in response to the respective portion being irradiated by radiation transmitted through the portion, and .

detecting, at S3, on each detector of the matrix, the radiation scattered by the associated respective portion of the load.

In some examples, the selecting performed at S2 comprises:

enabling the radiation scattered by the respective portion to reach an associated detector of a matrix of detectors, and inhibiting any other scattered radiation from reaching the associated detector.

In some embodiments, the selecting performed at S2 may be performed by the selection device 11 of the system of any one of the aspects of the disclosure.

In some embodiments, the detecting performed at S3 may be performed by the matrix 2 of the system of any one of the aspects of the disclosure.

In some examples, the method illustrated in Figure 8 may optionally comprise, at S1, emitting radiation for irradiation of the loads to inspect.

In some embodiments, the emitting performed at S1 may be performed by the source 1 of the apparatus and/or system of any one of the aspects of the disclosure.

In some examples, the method illustrated in Figure 8 may optionally comprise, at S4, detecting radiation after transmission through the load.

In some embodiments, the detecting performed at S4 may be performed by the additional detector 5 of the apparatus and/or system of any one of the aspects of the disclosure.

In some embodiments, the method of Figure 8 may further comprise generating, at S5, an image of the load, e.g. by using data associated with the matrix and/or the additional detector (when present). In some examples generating the image further comprises processing data associated with the matrix of the detection system. In some examples, the data comprises current data associated with a current zone of the load emitting scattered radiation, to take into account at least one property of other zones of the load. In some examples, the data comprises current data associated with a current respective portion of the load emitting scattered radiation, to take into account at least one property of other portions in a plane parallel to a direction of transmission of radiation; and/or a distance of the portion from the source of radiation. In some examples, processing the data comprises compensating for distortion caused by the detection system defining a main direction of detection forming an angle with respect to a direction of inspection of the load, and/or the detection system being positioned at a distance from the direction of inspection of the load. In some examples, processing the data further comprises estimating a nature of a material of the load, based on a detection of a level of scattered radiation and/or on a spectrum of energy of the scattered radiation.

In some embodiments, the generating performed at S5 may be performed by the analyser 3 of the apparatus and/or system of any one of the aspects of the disclosure.

In another aspect of the present disclosure, there is described a computer program product comprising program instructions to program a processor to carry out a method according to any aspect of the disclosure, or to program a processor to provide a system and/or apparatus and/or imager of any aspect of the disclosure.

Modifications and Variations

The load 8 may be any type of object and/or container, such as a holder, a vessel, or a box, etc. The load 8 may thus be, as non-limiting examples, a trailer and/or a palette (for example a palette of European standard, of US standard or of any other standard) and/or a train wagon and/or a tank and/or a boot of a vehicle such as a truck, a van and/or a car and/or a train, and/or the load 8 may be a “shipping container” (such as a tank or an ISO container or a non-ISO container or a Unit Load Device (ULD) container). It is thus appreciated that the load 8 may be any type of container, and thus may be a suitcase in some examples.

The system is configured to cause inspection of a cargo (not shown in the Figures) of the load through a material (usually steel) of walls of the load 8, e.g. for detection and/or identification of the cargo.

The system may be configured to cause inspection of the load, in totality (i.e. the whole load is inspected) or partially (i.e. only a chosen part of the load is inspected, e.g., typically, when inspecting a vehicle, a cabin of the vehicle may not be inspected, whereas a rear part of the vehicle is inspected).

The source 1 may comprise an accelerator, i.e. may be configured to produce and accelerate an electron beam on a metal target (such as tungsten and copper), sometimes referred to as a “focal spot”, to generate the photons of the radiation 22 (by the so-called braking radiation effect, also called “Bremsstrahlung”). Alternatively or additionally, the source 1 may be configured to be activated by a power supply, such as a battery of an apparatus comprising a vehicle and/or an external power supply.

The radiation 22 may comprise γ-ray radiation and/or neutron radiation. Non-limiting examples of irradiation energy from a source may be comprised between 50keV and 15MeV, such as 2MeV to 6MeV, for example. Other energies are envisaged.

In some examples the energy of the X-ray radiation may be comprised between 50keV and 15MeV, and the dose may be comprised between 2mGy/min and 30Gy/min (Gray). In some examples, the power of the source may be e.g., between 100keV and 9.0MeV, typically e.g. 2MeV, 3.5MeV, 4MeV, or 6MeV, for a steel penetration capacity e.g., between 40mm to 400mm, typically e.g., 300mm (12in). In some examples, the dose may be e.g., between 20mGy/min and 120mGy/min. In some examples, the power of the X-ray source may be e.g., between 4MeV and 10MeV, typically e.g., 9MeV, for a steel penetration capacity e.g., between 300mm to 450mm, typically e.g., 410mm (16.1 in). In some examples, the dose may be 17Gy/min.

In some examples the source 1 may be configured to emit the radiation 22 with successive radiation pulses. In some examples, the source 1 may be configured to emit the radiation as a continuous emission (e.g. the source 1 may comprise an X-ray tube).

The system and/or the apparatus may be mobile and may be transported from a location to another location (the system and/or apparatus may comprise an automotive vehicle). Alternatively or additionally, the system and/or the apparatus may be static with respect to the ground and cannot be displaced.

It should be understood that the radiation source may comprise sources of other radiation, such as, as non-limiting examples, sources of ionizing radiation, for example gamma rays or neutrons. The radiation source may also comprise sources which are not adapted to be activated by a power supply, such as radioactive sources, such as using Co₆o or Cs₁₃₇. In some examples, the inspection system may comprise other types of detectors, such as optional gamma and/or neutrons detectors, e.g., adapted to detect the presence of radioactive gamma and/or neutrons emitting materials within the load, e.g., simultaneously to the X-ray inspection.

In some examples, one or more memory elements (e.g., the memory of the analyser or a memory element of the processor) can store data used for the operations described herein. This includes the memory element being able to store software, logic, code, or processor instructions that are executed to carry out the activities described in the disclosure.

A processor can execute any type of instructions associated with the data to achieve the operations detailed herein in the disclosure. In one example, the processor could transform an element or an article (e.g., data) from one state or thing to another state or thing. In another example, the activities outlined herein may be implemented with fixed logic or programmable logic (e.g., software/computer instructions executed by a processor) and the elements identified herein could be some type of a programmable processor, programmable digital logic (e.g., a field programmable gate array (FPGA), an erasable programmable read only memory (EPROM), an electrically erasable programmable read only memory (EEPROM)), an ASIC that includes digital logic, software, code, electronic instructions, flash memory, optical disks, CD-ROMs, DVD ROMs, magnetic or optical cards, other types of machine-readable mediums suitable for storing electronic instructions, or any suitable combination thereof.

As one possibility, there is provided a computer program, computer program product, or computer readable medium, comprising computer program instructions to cause a programmable computer to carry out any one or more of the methods described herein. In example implementations, at least some portions of the activities related to the analyser and/or the detector may be implemented in software. It is appreciated that software components of the present disclosure may, if desired, be implemented in ROM (read only memory) form. The software components may, generally, be implemented in hardware, if desired, using conventional techniques.

Other variations and modifications of the system will be apparent to the skilled in the art in the context of the present disclosure, and various features described above may have advantages with or without other features described above. The above embodiments are to be understood as illustrative examples, and further embodiments are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

1. A detection system comprising:

a matrix of detectors, each detector being configured to detect radiation scattered by an associated respective portion of a load to inspect, the radiation being scattered in response to the respective portion being irradiated by radiation transmitted through the portion; and a selection device configured to, for each detector of the matrix:

enable radiation scattered by the respective portion of the load to reach the associated detector of the matrix, and inhibit other scattered radiation from reaching the associated detector.

2. The detection system according to claim 1, wherein each detector is configured to be associated with a respective portion of the load by being in a line of sight of the respective portion through the selection device.

3. The detection system according to claim 1 or claim 2, wherein the selection device is configured to act as a diaphragm and comprises:

a block configured to inhibit scattered radiation from reaching the matrix; and an aperture configured to let scattered radiation emitted by the respective portion to reach the matrix.

4. The detection system according to the preceding claim, wherein the aperture of the selection device is configured such that:

each respective portion corresponds to a voxel of the load, and/or each respective detector corresponds to a pixel of an image of the load generated using data associated with the matrix.

5. The detection system according to claim 3 or 4, wherein dimensions of the aperture are based on:

dimensions of the load to inspect; and/or a distance between the load to inspect and the selection device; and/or a distance between the selection device and the matrix of detectors; and/or a distance between the load to inspect and a source of radiation.

6. The detection system according to any one of the preceding claims, wherein dimensions of the matrix of detectors are based on:

7. The detection system of claim 6, wherein the matrix of detectors has a ratio of dimensions based on a ratio of dimensions of the load.

8. The detection system according to any one of the preceding claims, wherein the detection system defines a main direction of detection, the main direction of detection being parallel to a main direction of inspection of the load.

9. The detection system according to any one of claims 1 to 7, wherein the detection system defines a main direction of detection, the main direction of detection forming an angle with respect to a direction of inspection of the load, and/or the system being positioned at a distance from the direction of inspection of the load.

10. The detection system according to claim 9, wherein the matrix of the detection system has a trapezoid shape based on:

the angle of the main direction of detection with respect to the direction of inspection of the load, and/or the distance of the system to the direction of inspection of the load.

11. The detection system according to any one of the preceding claims, further configured to be movable with respect to the load.

12. An apparatus comprising:

at least one detection system of any one of claims 1 to 11; and at least one source configured to generate radiation configured to penetrate, at least partly, a load to inspect, the load generating scattered radiation in response to being irradiated.

13. The apparatus according to claim 12, further comprising shielding configured to inhibit radiation from the source from irradiating the matrix of the detection system.

14. The apparatus of claim 12 or claim 13, wherein the source is configured to emit a fan beam and/or a pencil beam of radiation.

15. The apparatus of any one of claims 12 to 14, wherein the source is further configured to emit radiation for inspection by transmission through the load to inspect.

16. The apparatus of any one of claims 12 to 15, wherein the source is configured to emit ionizing radiation.

17. The apparatus of any one of claims 12 to 16, wherein the source is configured to emit radiation comprising:

X-ray radiation and/or γ-ray radiation and/or neutron radiation.

18. The apparatus according to any one of claims 12 to 17, further comprising:

an additional detector configured to detect radiation from the load after transmission through the load.

19. The apparatus according to claim 18, further comprising shielding configured to inhibit radiation from the additional detector from irradiating the matrix of the detection system.

20. The apparatus according to any one of claims 12 to 19, wherein, in a pass-through and/or conveyor mode, the detection system is static with respect to the ground and the one or more loads are movable with respect to the ground.

21. The apparatus according to any one of claims 12 to 20, wherein, in a scan mode, the detection system is movable with respect to the ground and the one or more loads are static with respect to the ground.

22. The apparatus according to any one of claims 12 to 21, further comprising an analyser configured to process data associated with the matrix of the detection system.

23. The apparatus of claim 22, wherein the data comprises:

current data associated with a current zone of the load emitting scattered radiation, to take into account at least one property of other zones of the load.

24. The apparatus of claim 23, wherein the other zones comprise zones which have been previously irradiated.

25. The apparatus of any one of claims 22 to 24, wherein the data comprises:

current data associated with a current respective portion of the load emitting scattered radiation, to take into account:

at least one property of other portions in a plane parallel to a direction of transmission of radiation; and/or a distance of the portion from the source of radiation.

26. The apparatus according to any one of claims 22 to 25, wherein the analyser is further configured to process data associated with the detection system, to compensate for distortion caused by:

the detection system defining a main direction of detection forming an angle with respect to a direction of inspection of the load, and/or the detection system being positioned at a distance from the direction of inspection of the load.

27. The apparatus according to any one of claims 22 to 26, wherein the analyser is further configured to estimate a nature of a material of the load, based on a detection of a level of scattered radiation and/or on a spectrum of energy of the scattered radiation.

28. The apparatus according to any one of claims 22 to 27, wherein the source has an energy comprised between 50keV and 15MeV.

29. A method of inspection of a load, comprising:

selecting radiation scattered by each respective portion of a load to inspect, the radiation being scattered in response to the respective portion being irradiated by radiation transmitted through the portion, the selecting comprising:

enabling the radiation scattered by the respective portion to reach an associated detector of a matrix of detectors, and inhibiting other scattered radiation from reaching the associated detector; and detecting, on each detector of the matrix, the radiation scattered by the associated respective portion of the load.

30. The method of claim 29, further comprising:

generating radiation for irradiation of the load to inspect.

31. The method of claim 29 or claim 30, further comprising:

detecting radiation after transmission through the load.

32. The method of any one of claims 29 to 31, further comprising:

generating an image of the load.

33. The method of claim 32, wherein generating the image further comprises:

processing data associated with the matrix of the detection system.

34. The method of claim 33, wherein the data comprises:

35. The method according to claim 33 or claim 34, wherein the data comprises:

36. The method according to any one of claims 33 to 35, wherein process the data comprises compensating for distortion caused by:

the detection system defining a main direction of detection forming an angle with respect to a direction of inspection of the load, and/or the detection system being positioned at a distance from the direction of inspection of the load

37. The method according to any one of claims 33 to 36, wherein processing the data further comprises:

estimating a nature of a material of the load, based on a detection of a level of scattered radiation and/or on a spectrum of energy of the scattered radiation.

38. A computer program or a computer program product comprising program instructions to program a processor to provide a detection system of any one of claims 1 to 11 or apparatus of any one of claims 12 to 28, or to program a processor to carry out a method according to any one of claims 29 to 37.

Intellectual

Property

Office

Application No: GB1613065.0 Examiner: Mr David Burns