The present invention relates to x-ray scanning systems. More particularly, the present invention relates to an x-ray scanning system for scanning an object, as well as to a corresponding method and bracket.
Scanning machines are often used to scan objects. These machines emit a source radiation in the direction of the object being scanned. The reaction of the object with the source radiation produces a signature, which can be read by detectors so as to identify or analyze the object.
A problem is encountered when using x-ray scanning systems in that the geometry of a scanned object often does not permit for visibility of certain parts of the object. For example, where the object is a suitcase for travel, many scanners will provide images with limited or no visibility of the sides or edges of the containers. This provides a security risk wherein small or thin objects can be concealed at certain parts of the container. Moreover, scanners which provide for three-dimensional representations of an object are often very high in cost and can take a longer amount of time to complete a scanning operation.
Hence, in light of the aforementioned, there is a need for a device which, by virtue of its design and components, would be able to overcome or at least minimize some of the drawbacks of the prior art.
The present invention relates to x-ray scanning systems. More particularly, the present invention relates to an x-ray scanning system for scanning an object, as well as to a corresponding method and bracket.
A system of one or more computers can be configured to perform particular operations or actions by virtue of having software, firmware, hardware, or a combination of them installed on the system that in operation causes or cause the system to perform the actions. Performance of the actions may be automatic and/or in real time. One or more computer programs can be configured to perform particular operations or actions by virtue of including instructions that, when executed by data processing apparatus, cause the apparatus to perform the actions.
One general aspect includes a scanning system for scanning an object including: a scanning chamber for receiving the object to be scanned. The scanning system also includes a displacement assembly for displacing the object along a displacement path passing at least partially through the scanning chamber. The displacement path may be horizontal. The scanning system also includes a source mountable about the scanning chamber for emitting electromagnetic radiation against the object in the scanning chamber at an angle in a range between about 5° to about 8° and about 22° to about 30° relative to the displacement path so that the electromagnetic radiation impacts and passes through the object as it is displaced through the scanning chamber along the displacement path. The scanning system also includes a plurality of detectors mounted at least partially about the scanning chamber, each detector configured for detecting the electromagnetic radiation passed through the object, thereby scanning the object.
In one preferred aspect, the angle is in a range between about 5° to less than 8° and about 22° to about 30° and more preferably the angle is 22.5°.
The source may be configured for emitting electromagnetic radiation from a focal point as a beam having beam boundaries, the beam boundaries being separated by an angular interval of about 80°. The scanning chamber may be defined by opposed side surfaces and a third surface extending between the side surfaces and where one of the beam boundaries is aligned with one of the side surfaces of the scanning chamber. Each detector may include a detector card having a centre point and edges. Each detector may be inclined at a corresponding detector angle such that the centre point of each detector card is substantially perpendicular to the focal point. Moreover, the edges of each detector card may engage at least one of the third surface and the side surfaces of the scanning chamber. Edges of some detector cards may engage one of the side surfaces, and where the edges of other detector cards engage the third surface.
In another aspect, the plurality of detectors may also include two rows of detectors mounted about the scanning chamber, the first row of detectors being disposed adjacent to one of the side surfaces of the scanning chamber, and the second row of detectors being disposed adjacent to the third surface of the scanning chamber. The first and second rows of detectors may form an angle with respect to the displacement path between about 89° and about 45° and more preferably between about 80° and about 70°.
In another aspect, the source includes an x-ray emitter mountable to a mounting surface of an inclined support. The mounting surface of the inclined support may form an angle with respect to a horizontal between about 1° and about 45°. In a preferred aspect, the mounting surface of the inclined support may an angle with respect to the displacement path in a range between about 5° to about 8° and about 22° to about 30°.
The scanning chamber may be a tunnel extending at least partially through a frame. The displacement assembly may be, for example, a conveyor. The electromagnetic radiation may comprise x-rays.
The scanning system may further include means for correcting distortion of the image data including finding an optimal virtual plane where the source-detector rays are projected at equal distances and remapping the pixels by redistribution of information from a set of input pixels to a set of output pixels arrayed onto a virtual detector array.
In another aspect, there is provided a bracket fora scanning system for scanning an object. The bracket includes a bracket frame mountable to the scanning system, the bracket frame being inclined at an angle in a range between about 5° to about 8° and about 22° to about 30° relative to a horizontal. The bracket also includes a source for emitting electromagnetic radiation through the object, the source mountable to the bracket frame. The bracket also includes a plurality of detectors mountable to the bracket frame, each detector configured for detecting the electromagnetic radiation passed through the object, thereby scanning the object. The angle is preferably in a range between about 5° to less than 8° and about 22° to about 30° and more preferably the angle is 22.5°.
The bracket may further include means for correcting distortion of the image data including finding an optimal virtual plane where the source-detector rays are projected at equal distances and remapping the pixels by redistribution of information from a set of input pixels to a set of output pixels arrayed onto a virtual detector array.
In another aspect, there is provided a method of generating a three-dimensional image of a scanned object. Image data of an object is received at an input port, having been captured via a plurality of detectors disposed at least partially about the object receiving electromagnetic radiation emitted from a source inclined at an angle in a range between about 5° to about 8° and about 22° to about 30° relative to a horizontal. The method of generating also includes, by means of a processor, generating from the image data, an image representing a perspective view of the object. The method of generating also includes storing said image into a storage for presenting on a display, a three-dimensional representation of the object. The angle is preferably in a range between about 5° to less than 8° and about 22° to about 30° and more preferably the angle is 22.5°.
The method may further include the step of applying a distortion correction comprising finding an optimal virtual plane wherein the source-detector rays are projected at equal distances and remapping the pixels by redistribution of information from a set of input pixels to a set of output pixels arrayed onto a virtual detector array.
In another aspect, there is provided a data storage comprising data and instructions for execution by a processor to generate a three-dimensional image of a scanned object. The data and instructions include code means for receiving image data of an object, having been captured via a plurality of detectors disposed at least partially about the object receiving electromagnetic radiation emitted from a source inclined at an angle in a range between about 5° to about 8° and about 22° to about 30° relative to a horizontal, code means for generating from the image data, an image representing a perspective view of the object, and code means for storing said image into a storage for presenting on a display, a three-dimensional representation of the object. The angle is preferably in a range between about 5° to less than 8° and about 22° to about 30° and more preferably the angle is 22.5°.
The data storage may further include code means for correcting distortion of the image data including finding an optimal virtual plane where the source-detector rays are projected at equal distances and remapping the pixels by redistribution of information from a set of input pixels to a set of output pixels arrayed onto a virtual detector array.
In another aspect, there is provided a system for generating a three-dimensional image of a scanned object. The system includes an input port for receiving image data of an object, having been captured via a plurality of detectors disposed at least partially about the object and in an angled configuration wherein the plurality of detectors are inclined at an angle in a range between about 5° to about 8° and about 22° to about 30° relative to a horizontal. The system further includes a processor for generating from the image data, an image representing a perspective view of the object and a storage for presenting the image on a display as a three-dimensional representation of the object. The angle is preferably in a range between about 5° to less than 8° and about 22° to about 30° and more preferably the angle is 22.5°.
The system may further include means for correcting distortion of the image data including finding an optimal virtual plane where the source-detector rays are projected at equal distances and remapping the pixels by redistribution of information from a set of input pixels to a set of output pixels arrayed onto a virtual detector array.
In yet another aspect, there is provided a scanning system for scanning an object. The system includes a radiation source for emitting electromagnetic radiation toward an object to be scanned at an angle in a range between about 5° to about 8° and about 22° to about 30° relative to a horizontal. A plurality of detectors is disposed at least partially about a scanning area. Each detector may be mounted substantially perpendicularly in relation to the radiation source for capturing the radiation traversing the object from different angles and thereby scanning the object according to a perspective view. The angle is preferably in a range between about 5° to less than 8° and about 22° to about 30° and more preferably the angle is 22.5°.
The scanning system may further include means for correcting distortion of the image data comprising finding an optimal virtual plane wherein the source-detector rays are projected at equal distances and remapping the pixels by redistribution of information from a set of input pixels to a set of output pixels arrayed onto a virtual detector array.
Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods. Such performance may be automatic and/or in real-time.
The components, advantages and other features of the system and corresponding method and bracket will become more apparent upon reading of the following non-restrictive description of some optional configurations, given for the purpose of exemplification only, with reference to the accompanying drawings.
The present invention relates to x-ray scanning systems. More particularly, the present invention relates to an x-ray scanning system for scanning an object, as well as to a corresponding method and bracket.
In the following description, the same numerical references refer to similar elements. Furthermore, for the sake of simplicity and clarity, namely so as to not unduly burden the figures with several references numbers, not all figures contain references to all the components and features, and references to some components and features may be found in only one figure, and components and features of the present invention illustrated in other figures can be easily inferred therefrom. The embodiments, geometrical configurations, materials mentioned and/or dimensions shown in the figures are optional, and are given for exemplification purposes only.
Furthermore, although the present invention may be used for scanning objects, such as for threat detection or imaging, and as a result, is sometimes described in the context of a possible use for detecting dangerous objects and/or producing 3D images, it is understood that it may be used for other purposes, and in other fields and/or activities. For this reason, expressions such as “scan”, “threat detection”, “dangerous object”, “chemical”, “imaging”, “3D”, etc. as used herein should not be taken as to limit the scope of the present invention to the detection of threats or the production of 3D images in particular. These expressions encompass all other kinds of materials, objects and/or purposes with which the present invention could be used and may be useful, as can be easily understood.
Broadly described, the present invention provides a system, method, and bracket which can improve the process for scanning and detecting an object so as to generate a 3D image of said object, as but one possible example of a use of the invention.
According to a general aspect as shown in
The system 10 has a frame 50, an example of which is also shown in
The frame 50 has a scanning chamber 54, an example of which is shown in
In one possible embodiment, the scanning chamber 54 can be a displaceable drawer into which the object 12 can be placed so as to be scanned. The drawer scanning chamber 54 can have two vertical side surfaces 56 supported and connected together by a bottom horizontal third surface 58 upon which the object 12 can rest. In another possible embodiment, the scanning chamber 54 can consist of a relatively large framework into which vehicles and other large devices can be placed. This framework scanning chamber 54 can have two vertical side surfaces 56 connected together by a top horizontal third surface 58, thus defining a passage through which the object 12 can be displaced. Such a framework scanning chamber 54 can advantageously be used to scan cargo containers and other similar large objects.
In yet another possible embodiment, an example of which is shown in the figures, the scanning chamber 54 is a tunnel 55. The tunnel 55 can have an opening at each of its ends, thus defining a passage or channel which extends through some, or all, of the frame 50. The dimensions of the tunnel 55 can vary depending upon a number of factors, such as the following non-limitative list: the nature and shape of objects 12 to be scanned, the cost of implementation of the system 10, and the space available for the system 10. Although shown as substantially box-like, the tunnel 55 can be non-linear, winding, or take other configurations which permit it to receive the object 12 to be scanned.
The system 10 also has a displacement assembly 20, an example of which is shown in
Indeed, in the optional embodiment where the scanning chamber 54 is a drawer, the displacement assembly 20 can be a mechanism which engages the drawer scanning chamber 54 from the exterior of the drawer scanning chamber 54 so as to open and close the drawer scanning chamber 54. In the optional embodiment where the scanning chamber 54 is a framework, the displacement assembly 20 can be a vehicle or other similar mover of the object 12 so as to engage the framework scanning chamber 54 by moving the object 12 along a displacement path into the passage defined by the framework scanning chamber 54 and at least partially through the scanning chamber 54. In the optional embodiment where the scanning chamber 54 is a tunnel 55, the displacement assembly 20 can be a conveyor 22 or conveyor belt. The conveyor 22 engages the scanning chamber 54, which can be a tunnel 55, by extending through the scanning chamber 54 so as to convey the object 12 through the scanning chamber 54.
In any of its configurations, the displacement assembly 20 can stop, accelerate, decelerate, or otherwise control the displacement of the object 12, and its direction, within or through the scanning chamber 54. Such functionality advantageously allows for the object 12 to be rescanned or further analyzed, if desired. Furthermore, and in light of the preceding description of some of its optional embodiments, it can be appreciated that the displacement assembly 20 can take many different configurations, and engage the scanning chamber 54 in many different ways.
The system 10 also has a source 30, an example of which is also shown in
The source 30 is “mountable to the frame about the scanning chamber”, which means that it can fixedly or removably attached to the frame 50 in proximity to the scanning chamber 54. The source 30 can also mounted to the frame 30 so that it can rotate, pivot, or be displaced around the object 12, which can remain in a fixed position. The actual location and position of the source 30 can depend on the configuration of the scanning chamber 54 and the displacement assembly 20, among other possible factors. In some embodiments, the source 30 can be mounted to the frame 50 at a location below the displacement assembly 20, as shown in
The source 30 can have many different configurations. In one possible embodiment, an example of which is shown in
In some embodiments, an example of which is shown in
In some embodiments, the source 30 can emit EM radiation or X-rays from a focal point 38 as a beam 39. The beam 39 can be any fan or cone beam having an angular width as it is emitted from the focal point 38. The angular width of the beam 39 observed from one direction may be different from the angular width of the same beam 39 observed from another direction. This can be better appreciated by comparing the example of the beam 39 as shown in
The system 10 also has a plurality of detectors 40, examples of which are shown in
In some embodiments, each detector 40 includes a detector card 42 which has a centre point 44 and edges 46. The detector card 42 can be any suitable detector card 42 such as those manufactured by Detection Technologies Ltd., United Kingdom. Each of these detector cards 42 can have a centre point 44, which corresponds to the geographical centre of the detector cards 42. The edges 46 of each detector card 42 define its boundaries. The detectors 40 and/or the system 10 can be linked to a central processing Unit (CPU) 100 (see
According to an embodiment described and illustrated herein, each detector 40 comprises a first scintillator 80, a filter 82, and a second scintillator 84, all of which are sandwiched together, as is schematically represented in
Each detector 40 is inclined at a detector angle D. In most embodiments, but not necessarily all, the detector angle D is defined with respect to a horizontal plane. The detector angle D of one or more of the detectors 40 is different than the detector angle D of an adjacent detector 40. For example, this can mean that the detector angle D of at least one detector 40 is different than the detector angle D of all the other detectors 40. This can also mean that each detector 40 has a detector angle D that is different from the detector angles D of its neighbouring detectors 40. The term “adjacent” in this context refers to neighbouring detectors 40, whether they are located directly next to, or nearby, the at least one detector 40 having a different detector angle D. The determination of the detector angle D for each detector 40 can depend upon numerous factors such as, but not limited to: the angle of the source 30 relative to the horizontal, the position of the source 30 relative to the scanning chamber 54, the position of the centre point 44 of each detector card 42 relative to the source 30, etc.
In some embodiments, the detector angle D of each detector card 42 may optionally be determined by satisfying the following two requirements: 1) the centre point 44 of each detector card 42 is substantially perpendicular to the focal point 38 of the beam 39, and 2) each detector card 43 is positioned as close as possible to the focal point 38 of the beam 39.
Reference is made to
Returning to
According to another general aspect, there is a provided a bracket 60 for a scanning system, such as the one described above. Referring now to
The image processing of the above-described scanning system will now be better explained, with reference to
In the context of the present description, the term “processor” refers to an electronic circuitry that can execute computer instructions, such as a central processing unit (CPU), a microprocessor, a controller, and/or the like. A plurality of such processors may be provided, according to embodiments of the present invention, as can be understood by a person skilled in the art. The processor may be provided within one or more general purpose computer, for example, and/or any other suitable computing device. Execution of some or all of the computer instructions by the processor may be performed automatically and/or in real-time.
Still in the context of the present description, the term “storage” refers to any computer data storage device or assembly of such devices including, for example: a temporary storage unit such as a random-access memory (RAM) or dynamic RAM; a permanent storage such as a hard disk; an optical storage device, such as a CD or DVD (rewritable or write once/read only); a flash memory; and/or the like. A plurality of such storage devices may be provided, as can be understood by a person skilled in the art.
According to the present embodiment, the X-Ray source 30 emits a continuous spectrum of X-Rays, ranging from a lower energy range such as 10 to 70 kV (+/−) up to higher energy ranges such as 60 to 250 kV (+/−).
It is to be understood that depending on particular embodiments of the present invention, the lower energy range may be as low as 1 kV and the higher energy ranges may be greater that the values given above in relation to the described embodiment.
As the object 12 is subjected to the X-Rays, the detectors 40 capture the X-Ray energy that traverses the object 12. As previously mentioned, the first scintillator 80 detects a lower portion of an X-Ray signal, while the second scintillator 84 detects a higher portion of the X-Ray signal. The high energy range penetrates more easily through denser materials, while the low energy range provides better contrast for image portions corresponding to lighter materials.
Broadly, each of the scintillators 80, 82 converts the X-Ray energy to light. A photo-diode 86 then captures the light and generates a corresponding electric signal. The electric signal is further digitized by a converter 88. The digitized value is associated to a pixel of the image which represents the object.
In the present embodiment, the detectors' physical arrangement in the scanner system determines the arrangement of the raw data extracted therefrom. More particularly, according to the embodiment illustrated herein, detectors 40 are aligned in a row, positioned as previously mentioned, along an “L”-shaped configuration, as schematically represented in
As the object 12 moves through the scanning chamber 54, the detectors perform scan captures sequentially at a given rate, which may depend on their integration time, i.e. exposure time. Thus several of said “rows” of data are acquired in a given scanning process. The rows are juxtaposed as schematically represented in
In
As previously mentioned, the X-Ray energy is translated into a digitized value, for each pixel, via the scintillators 80, 82, the photo-diodes 86 and the converter 88. In the conversion by the photo-diodes 86 of the light into an electric signal, some error may occur, in that a given light source may result in different electrical signals due to the fact that every detector card behave slightly differently to the presence or absence of X-Ray signal.
Thus, in order to correct these variations and for the final image to appear more homogeneously, a normalization module 102, by means of the CPU 100, normalizes (or “calibrates”) each pixel of the low and high energy captures, by correcting an offset and a gain in the light conversion.
The offset is determined based on the signal perceived by the scintillators of the detectors when no source is emitted. When no source is emitted, as represented by the dark band 97 appearing in
After removing the offset, there are still variations in the capture of each detector when fully exposed to the source emission, as represented by the light band 98 appearing in
The high and low energy information is then fused, at an image fusion module 104, by means of the CPU 100. More particularly, each pixel of the image results from a combination of high energy data in some proportion and low energy data in some proportion. Depending on the density of the material detected, it may be desirable to emphasize the low energy information or the high energy information in suitable proportion. Indeed, as previously mentioned, the high energy range penetrates more easily through denser materials, while the low energy range provides better contrast for image portions corresponding to lighter materials. The high and low energy data is thus combined accordingly to better illustrate particular regions of the image. For example, a pixel may be the result of 25% of the high energy data and 75% of the low energy data because it is determined by the X-Ray signal is relatively high, meaning that it is more desirable to see contrast. The proportion of high and low energy is determined based on ranges of low energy data value and/or high energy data value for a particular pixel.
An atomic number is then associated to each pixel of the image, via an atomic number calculation module 106, by means of the CPU 100. More particularly, the atomic number is determined based on the low energy absorption data and high energy absorption data, as well as a signal level of a source emission 30.
In a calibration step, materials having a known atomic number are scanned, in order to correlate each of their particular combination of low and high energy, for a given source signal level, with their atomic number. Based on the correlations made based on the known materials, a set of reference data is generated. The reference data includes combinations of low and high energy (at a given source signal level) and their corresponding atomic number. Thus, for each pixel, the combination of the corresponding low and high energy data, is correlated with a corresponding atomic number.
The image is then sharpened via a filtering module 108, by means of the CPU 100, in order to reduce blurriness when the image is displayed for viewing on a display 110. More particularly, the image data is convoluted to enhance portions of the image representing edges of the object 12.
The resulting image is also corrected for geometric distortion. Geometric distortion can potentially hinder the analysis of the image. In the strongly compressed regions, a large amount of data is stored in a very small area. Furthermore, the geometric distortion correction will straighten lines which may appear curved in the image due to geometric distortion. An optimal correction that is applied on the image regardless of the scanned item height is preferably implemented.
The distortion correction is applied by transforming the measured data received from the X-ray detector into equal distance projections. The optimal virtual plane is where the source-detector rays are projected at equal distances. It is preferable to find the projection plane that minimizes the difference of distance between every adjacent pair of points. The minimization problem can be set as minimizing the maximum error (difference between two adjacent projected points) and thus formulated as follows:
This procedure is done only once for a given geometry and the mapping function can be applied directly on the archives of a given machine.
The corrected signals correspond to signals which would have been detected by an imaginary X-ray detector arranged substantially perpendicular to the center line of the X-ray fan beam shape. Image re-projection involves the redistribution of information from a set of input pixels to a set of output pixels array onto a virtual detector array having virtual pixels that are spaced equidistantly. Determining a radiation amplitude value for the virtual pixel comprises interpolating a value from the radiation amplitude values of the corresponding real detector pixel and neighboring real detector pixels.
Once this actual pixel is determined, an interpolation technique then is applied to it and its nearest neighbors on the real detector array to compute an x-ray absorption amplitude value to be assigned to the virtual pixel. This process is repeated until absorption amplitude values have been assigned to each of the virtual pixels in the virtual array.
The resulting image is then stored in a database 112, from the basis of which a three-dimensional or perspective representation of the object 12 may be presented on the display 110.
Embodiments of the present invention thus provide the advantage of generating a three-dimensional or perspective representation of the object 12, by virtue of the detectors being positioned at different angles depending on their location in relation to the source emission, and of enhancing detection capabilities, thereby allowing for an operator to better analyze the object 12.
Further advantageously, such a three-dimensional or perspective representation may provide more a revealing image of the object 12 when compared to two-dimensional images generated by traditional scanners. More specifically, such a representation may allow a user to visualize more walls or boundaries of the object 12, and may have fewer “dark spots” corresponding to parts of the object 12 which have planes aligned with the plane of the EM radiation emitted by the source.
It is to be understood that, in accordance with alternate embodiments, the above-described system and method may be adapted to operate with a single energy level of X-Ray signal captured at the detectors, as well as a plurality, i.e. two or more of such energy levels of X-Ray signal (instead of only low energy and high energy, as in the context of the above-described embodiments). Indeed, any suitable ranges of energy levels may be defined and captured by the detectors and further processed, for example to obtain more information on the composition of the object being scanned.
Of course, numerous other modifications could be made to the above-described embodiments without departing from the scope of the invention, as defined in the appended claims.
This patent application is a non-provisional of and claims priority to and the benefit of U.S. Provisional Patent Application No. 62/670,123, filed on May 11, 2018, entitled “X-RAY SCANNING SYSTEM AND METHOD”, which is incorporated by reference in its entirety.
Number | Date | Country | |
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62670123 | May 2018 | US |