All of the foregoing applications and patents are hereby incorporated by reference herein in their entireties.
The present invention relates to the field of x-ray imaging of personnel, packages, or other subjects to detect concealed objects.
Current personnel screening systems using backscatter and millimeter wave technology can provide images representative of the surface of the scanned subject, but, insofar as they may well not penetrate the entirety of the scanned subject, they lack the capability to image items of interest located on the far side of the subject, or items of interest that return a signal response similar to the background surrounding the subject, or items artfully concealed on the subject.
In an attempt to increase the detection accuracy of such screening systems, additional scans are required that might further necessitate repositioning the subject to be scanned. These additional scanning requirements, while possibly increasing detection accuracy, significantly reduce the rate of throughput of such systems that are generally implemented under circumstances that experience large volumes of scanning.
A system that provides both accurate and effective imaging at a high throughput rate and requires inspected subjects to be exposed to only a low dose of radiation is particularly desirable in such applications.
Accordingly, the present invention is directed toward providing an apparatus and method of scanning that can achieve these desired objectives.
In accordance with preferred embodiments of the present invention an apparatus is provided that ascertains a material feature associated with a subject, and in certain embodiments, generates one or more images of the subject. The apparatus generally includes a first carriage, a second carriage, at least one vertical positioner, and at least one detector. Each carriage includes a source that is adapted to produce a beam of penetrating radiation incident on the subject. The vertical positioner is adapted to synchronously displace each carriage with respect to the subject in a direction having a vertical component. The at least one detector receives radiation produced by at least one of the sources after interaction of the radiation with the subject. The detector may be disposed on the first carriage. The subject may be a person.
The penetrating radiation produced by each source may be in the form of x-ray radiation. Each source may be adapted to produce a pencil beam of radiation. Each source may also have a scanner adapted to move the beam of penetrating radiation produced by the source transverse to the direction of motion of the carriages. Each scanner may be in the form of a chopper wheel and the chopper wheel may be adapted to provide interleaved beams.
Each carriage may include a plurality of detectors. Each plurality of detectors may include at least one of a scatter and transmission detector.
The first and second carriages may produce substantially oppositely directed beams of penetrating radiation.
The transmission detector of the first carriage may be disposed at an elevation substantially equal to that of the source of the second carriage.
In one embodiment of the present invention the first and second carriages may be structurally coupled. Both carriages may be coupled to a single mechanical platform wherein the at least one positioner is adapted to move the single mechanical platform in a direction having a vertical component.
In another embodiment of the present invention each source may be an intermittently irradiating source providing a temporally interlaced irradiation pattern.
An embodiment of the present invention may include a displacement encoder.
The positioner of the apparatus may include at least one of a rotary motor coupled to a lead screw, a rack and pinion system, an electromechanically propelled system, a hydraulic piston or a pulley system in accordance with an embodiment of the present invention.
The apparatus may include a processor for receiving a signal from the at least one detector and for producing an image based at least on the signal and may further include a processor for electronically combining the images produced by each detector in one embodiment.
In accordance with a related embodiment of the present invention the apparatus may include an enclosure for containing the carriages and the at least one positioner during the course of operation. At least one stationary detector may be coupled to the enclosure. The enclosure may be an environmentally controlled enclosure. The enclosure may be sealable from an external environment.
In an embodiment of the present invention each source may be a pulsed source adapted to intermittently irradiate the subject.
In accordance with another embodiment of the present invention an apparatus for ascertaining a material feature associated with a subject is provided that includes a first carriage, a second carriage and at least one vertical positioner. The first carriage includes a source adapted to produce a beam of penetrating radiation incident on the subject and a first detector for detecting penetrating radiation scattered by the subject. The second carriage includes a second detector for detecting penetrating radiation produced by the source of the first carriage and transmitted through the subject. The at least one vertical positioner is adapted to synchronously vary the position of each carriage with respect to the subject in a direction having a vertical component. The positioner may act on the first carriage to vary the relative position of the source on the first carriage with respect to the subject.
In accordance with another embodiment of the present invention an apparatus is provided for ascertaining a material feature associated with a subject. The apparatus includes two vertically disposed arrays of sources adapted to produce beams of penetrating radiation, at least one detector for receiving radiation produced by at least one of the sources after interaction of the radiation with the subject, and a controller for activating at least one source in at least one of the arrays independent from the other sources in the same array.
In a related embodiment the at least one detector of the apparatus includes two vertical arrays of detectors and a processor for processing detection data received by each detector during a specified time interval.
In another related embodiment the apparatus includes a scanner adapted to move at least one beam of penetrating radiation produced by at least one of the sources.
In accordance with another embodiment of the present invention a method is provided for inspecting a subject. The method has steps of: moving a first carriage having coupled to it a first source adapted to produce a beam of penetrating radiation incident on the subject, moving in synchronization with the first carriage a second carriage having coupled to it a second source adapted to produce a beam of penetrating radiation, detecting with at least one detector radiation produced by at least one of the sources after interaction of the radiation with the subject, generating detector output signals based on radiation received by the at least one detector, and characterizing the subject on the basis of the detector output signals. The at least one detector may be coupled to at least one of the first carriage and the second carriage.
In a related embodiment the method further includes scanning the beam of penetrating radiation produced by the source in a direction transverse to the direction of motion of the carriages.
In another related embodiment the method further includes creating an image based on radiation detected by the first and second detectors.
In yet another related embodiment the method include the steps of: scanning the beam of penetrating radiation produced by the source coupled to the second carriage in a direction transverse to the direction of motion of the carriages, generating detector output signals based on radiation received by the first and second detectors and creating an image based on radiation detected from the first and the second beam. In any of the described methods for inspecting a subject the subject may be a person.
In accordance with another embodiment of the present invention a method is provided for inspecting a subject. The method includes generating beams of penetrating radiation at a temporally varying elevation, the beams of penetrating radiation generated by at least one first source positioned to direct the radiation in a first direction toward the subject and at least one second source positioned to direct penetrating radiation in a second direction toward the subject and detecting with at least one detector the radiation produced by at least one of the sources after interaction of the radiation with the subject. The at least one first source may comprise a first plurality of sources disposed at distinct vertical heights and the at least one second source may comprise a second plurality of sources at distinct vertical heights.
The present invention relates to the field of screening cargo or any other packages and/or subjects.
The foregoing features of the invention will be more readily understood by reference to the following detailed description taken with the accompanying drawings:
Definitions. As used in this description and the accompanying claims, the following terms shall have the meanings indicated, unless the context otherwise requires:
A “carriage” is a moveable system including a source and/or a detector of penetrating radiation. A carriage may include a detector that detects radiation; however, it is not required to.
A “vertical positioner” is a system component capable of displacing a carriage in a direction having a vertical component. A positioner may include an actuator, such as a motor, and attendant mechanical linkages or couplings.
A “vertically disposed array” is a plurality of objects, generally sources or detectors, disposed in a configuration having a vertical component such that at least one source in a vertically disposed array of sources is at a different elevation than at least one other source in the same vertically disposed array.
Configuring a detector to sense a particular kind of radiation may be achieved by modifying the detectors output, detection period, and/or sensitivity level. For example, each detector may output detected information to a processor specifically configured to process the detected signal. Further, the processor configuration may alternate depending on what type of radiation is detected during any given time interval. The detectors may be configured, for example, so that during the course of the time interval during which source 102 is producing a beam of radiation, detectors 104, 105, and 106 are configured to detect backscatter radiation, detectors 114 and 115 are configured to detect forward scatter radiation, and detector 116 is configured to detect transmission radiation. In the same example the detectors may be configured such that during the course of another time interval, defined by source 112 producing a beam of radiation, detectors 114, 115, and 116 are configured to detect backscatter radiation, detectors 104 and 105 are configured to detect forward scatter radiation, and detector 106 is configured to detect transmission radiation. This is just a single example of how the detectors may be configured to operate and the configuration is amenable to the provided system components and particular application. As such, various configurations, which may not be explicitly described may be provided in accordance with embodiments of the present invention.
Carriage 110, similar to carriage 100, includes three detectors that are coupled to it. The three detectors coupled to carriage 110 include detector 114 configurable to detect forward scatter radiation, detector 116 configurable to detect transmission radiation, and detector 115 also configurable to detect forward scatter detection. These detectors, as those on carriage 100, may each be configured, as discussed in the example above, to detect each type of radiation, including forward scatter, transmission, and/or backscatter radiation.
Carriages 100 and 110 are each maintained at substantially the same elevation throughout a scan. Carriages 100 and 110 are generally each coupled to separate vertical positioners that move the carriages along the trajectory illustrated by lines 108 and 118 respectively, as further illustrated in
As the source illustrated in
In a preferred embodiment the source of each carriage may be adapted to produce pencil beam x-rays. This may be achieved through the use of a collimator or by any means of producing a narrow beam of penetrating radiation. The source may be further adapted in a preferred embodiment to scan a subject in a direction transverse to the generally vertical direction of travel by the carriage. The scanning may be achieved using devices including, but not limited to, chopper wheels, electromagnetic steering devices, or any other scanning systems.
Two of the detectors configurable to detect forward scatter radiation on each carriage are disposed, in an embodiment, at a vertically offset distance from the corresponding source, such that the scattered radiation that results from the beam of penetrating radiation incident on the subject is detected. Although detector 106 may be configured to detect scatter radiation, detectors 104 and 105 may be more optimal than detector 106 at detecting forward scatter radiation resulting from the beam of source 112 interacting with a subject disposed between the carriages. Similarly, detector 116 may be configured to detect forward scatter radiation, but detectors 114 and 115 may be more optimal than detector 116 at detecting forward scatter radiation resulting from the beam produced by source 102 interacting with a subject due to the vertical offset of detectors 114 and 115 from source 102.
To achieve coordinated motion of the carriages, structural coupling that allows the carriage to move as a single body may be provided.
In use, a subject enters a vicinity of the inspection system and then the carriages are displaced vertically as the subject is scanned from at least two sides in a single pass. As a new subject enters the portal for scanning, the carriages can begin scanning the subject from their current position as they are displaced vertically in the opposite direction of displacement performed in the previous scan. For example, one subject is scanned as the carriages are displaced in a vertical direction decreasing in elevation and after the scan is completed and the next subject enters, the next subject may be scanned as the carriages are displaced in a vertical direction increasing in elevation.
In another embodiment of the present invention each carriage may include a source without any detectors coupled to the moveable carriage. For example, carriages 100 and 110 may each be provided without any of detectors 104, 105, 106, 114, 115, and 116. In this example, stationary detectors may be provided that detect transmission and/or scatter radiation as the carriages are displaced and the sources alternate activation. The stationary detectors in this example may still be configurable. The stationary detectors may also be provided, for example, in an array that extends approximately the length of travel of the carriages, thereby allowing them to detect radiation similar to the detectors attached to the carriages illustrated in
While
In one embodiment the positioner may be coupled to a displaceable member that subject 120 may be disposed on, as opposed to the positioner being coupled to the carriages. In the embodiment where the positioner is attached to a displaceable member that subject 120 may be disposed on, for example a mechanical platform located between two carriages, the positioner may vary the height of the member in a direction having a vertical component such that the subject or some region of the subject is scanned by the carriages. In this embodiment the same images produced through moving the carriages in synchronization in a direction having a vertical component are achieved because both embodiments provide for a variation in the relative orientation of the subject with respect to the carriages, while maintaining each carriage at an elevation that does not change with respect to the other carriage.
In
Some embodiments of the present invention may relate to methods and systems for inspecting objects by means of penetrating radiation that use multiple x-ray sources, which may be individually activated, as described in U.S. Patent Application Publication No. 2007/0258562 (issued as U.S. Pat. No. 7,505,562), hereby incorporated by reference herein in its entirety.
X-ray sources may be based on field-emission cathodes, offering advantages in both spatial and temporal resolution when compared with thermionic sources. Because field emission of electrons is produced by a high electric field, no heating is necessary, whence such electron emitters are commonly referred to as cold cathodes. The electron beams emitted by such devices may have low divergence and thus provide ease of focusing. Moreover, the virtually instantaneous response of the source offers time gating capabilities comparable with the time resolution of the control circuit, and may be as fast as nanoseconds, using current technology.
Zhang et al., A Multi-beam X-ray Imaging System Based on Carbon Nanotube Field Emitters, in Medical Imaging 2006, (Proceedings of SPIE, Vol. 6142, Mar. 2, 2006), reported the fabrication, by Xintek, Inc. of Research Triangle Park, NC, of a linear array of 5 X-ray sources, each with a focal spot between 200 and 300 μm, based on the use of carbon nanotube (CNT) electrodes. Electron currents in the range of 0.1-1 mA were reported at an accelerating voltage of 40-60 kVp. The lifetime of the cold cathode was estimated to exceed 2000 hours. For an accelerating voltage of 200 kV, a beam current of 13 mA has been measured. The aforesaid Zhang et al. paper is incorporated herein by reference. Devices with 1000 pixels per meter and pulse repetition rates on 10 MHz can be envisioned with technology within the current state of the art.
The use of CNT cold cathodes in the context of an x-ray source is also described by Cheng et al., Dynamic radiography using a carbon-nanotube-based field-emission X-ray source, 75 Rev. Sci. Instruments, p. 3264 (2004), while the use of CNT cold cathode source arrays in a scanning context is described by Zhang et al., Stationary scanning x-ray source based on carbon nanotube field emitters, 86 Appl. Phys. Lett., p. 184104 (2005), both of which articles are incorporated herein by reference.
Moreover, the use of CNT cold cathode source arrays in tomography is discussed by Zhang et al., A nanotube-based field emission x-ray source for microcomputed tomography, 76 Rev. Sci. Instruments, p. 94301 (2005), which is also incorporated herein by reference.
Discrete cold cathode sources may advantageously provide for electronically turning on the sources, and with low latency (on the nanosecond scale), in a sequential manner, thereby forming pencil beams, as often practiced in the x-ray imaging arts, or, alternatively, selecting a pattern of sources at a given time to form coded beams. The development of CNTs has allowed important technical challenges related to current stability and cathode life time to be overcome.
The general operation of a cold cathode x-ray source, designated generally, in
While
Application of discrete x-ray sources for x-ray imaging, in accordance with the present invention, varies with the dimensionality of the x-ray source array (one-, two-, or three-dimensional), the scanning mode (raster or pattern), the dynamic use of different or varying energies, and the use of time gating.
An embodiment of the invention is described with reference to
Referring now to
In accordance with further embodiments of the present invention, a system with controlled velocity, designated generally by numeral 1040, is described with reference to
Further versatility may be achieved using a related embodiment such as that shown in
Interlacing can be useful in cases where, due to technical limitations or by design, the minimum distance between two sources is 1 cm, but the required resolution for a specific applications demands sources placed 4 mm apart. On a cylinder, three one-dimensional arrays are placed at 120 degrees one from another and shifted vertically by 3.33 mm. Each array will scan lines 1 cm apart, but because of the vertical shift, the resulting image for a complete rotation of the cylinder will have a resolution of 3.33 mm. This mode of operation is referred to as “interlaced mode.” For the system depicted in
In accordance with further embodiments of the present invention, carbon nanotube x-ray sources configured in a linear or two-dimensional are triggered sequentially as described above. Other discrete x-ray sources that currently exist or that may be developed in the future may also be employed in a substantially similar manner, and are within the scope of the present invention as described herein and as claimed in any appended claims.
The use of x-ray source arrays of this type for this application may be particularly advantageous for the following reasons:
Another embodiment of the invention is now described with reference to
Scatter detectors 1114, which may be backscatter or sidescatter detectors, for example, are positioned to capture scattered x-rays. The person being scanned walks through the x-ray beams 1116 or is transported through by means such as a conveyor 1118 or people mover. A hand-hold 1119 may also be provided. Separate sources 1110 may be activated sequentially to provide spatial resolution in accordance with known algorithms.
Yet a further embodiment of the present invention is shown in
Alternatively, electromagnetic scanners may be employed, such as scanner 2104 (shown in
In cases where flying-spot systems are realized by mechanical means such as rotating hoops and chopper wheels, these aforesaid criteria may be met by synchronization of the motion of the mechanical chopper elements, biased by phase offsets. A system capable of such operation is demonstrated in U.S. Pat. No. 7,400,701, hereby incorporated by reference herein in its entirety. Thus, for example, where collimators are rotated to define the path of emergent x-ray beam 2023, close-loop motion controller systems known in the art may be employed to drive the rotation of the collimators. The duty cycle is controlled by setting the fan aperture (the total sweep angle of a beam, i.e., the angle between external beams 2023 and 2024 of a single source), equal to 2π times the duty cycle. In systems where the emitted radiation can be controlled electronically, any desired sequence of irradiation or range of sweep may be set, without limitation, entirely by electronic or software control.
By virtue of temporal sequencing which reduces or eliminates cross-talk, sources may be placed in greater proximity than otherwise possible. In particular, sources 2013, 2015 and 2017 may be disposed in a single plane, which advantageously permits virtually simultaneous on/off control of the x-rays regardless of the speed with which the object is passing by the imagers.
The system described may advantageously provide for an image to be derived from the perspective of each successive source 2013, 2015 and 2017, which emit beams 2023-2028.
The beams from each imager sweep in sequence, such that no more than one imager is emitting radiation at a time. Thus, source (or ‘imager’) 2013 sweeps its beam first. Radiation scattered from an object 2000, as represented by rays 2044, is received by all of the detectors 2031-2036 and transmitted to a processor 2040 to obtain images of the object, which may be conveyed through the system by an optional mechanized conveyor 2029. The signals from each of the detectors are acquired as separate channels by an acquisition system. This process is repeated for each of the three imagers, creating “slices” of the object as it moves by.
Referring now to
The signals from the detectors can be selectively used to reconstruct an image of the object. Since scattered photons 2044 detected by detectors 2033 and 2034 from source 2013 are as useful as scattered photons from source 2017, these same detectors can be shared among all sources, and result in improved scatter collection with efficient use of the detector hardware.
Embodiments of this invention, furthermore, may advantageously allow multi-view Flying-Spot X-ray Scatter imaging to be practiced in a smaller operational footprint by eliminating cross talk, and by allowing closer positioning of the individual imagers for each view. The close positioning of these imagers (where an “imager” refers to a source, at least one detector, and associated electronics and signal processing) may also allow sharing of scatter detectors between, or among, imagers, allowing more scatter collection for improved image quality, with efficient use of detector hardware.
In applications where scanning of selective regions of the object is desired, co-planar positioning of the imagers allows simultaneous on/off control of the x-rays regardless of the speed with which the object is passing by the imagers. This greatly simplifies the design of the control of x-ray emissions from each imager in the multi-view inspection system, thus individual sequencing of x-ray emissions need not be performed as is typically practiced in systems in which emission is not co-planar.
The described embodiments of the invention are intended to be merely exemplary and numerous variations and modifications will be apparent to those skilled in the art. All such variations and modifications are intended to be within the scope of the present invention as defined in the appended claims.
The present application is a continuation of U.S. patent application Ser. No. 12/272,056, filed Nov. 17, 2008, and issuing as U.S. Pat. No. 7,809,109 on Oct. 5, 2010, which is a continuation-in-part application of U.S. patent application Ser. No. 11/737,317, filed Apr. 19, 2007, and like those applications, respectively, the present application claims priority to U.S. Provisional Application No. 60/794,295, filed Apr. 21, 2006, and to U.S. Provisional Application No. 60/988,933, filed Nov. 19, 2007. U.S. patent application Ser. No. 12/272,056 is also a continuation-in-part application of U.S. patent application Ser. No. 12/171,020, filed Jul. 10, 2008, which is a continuation application of U.S. patent application Ser. No. 11/097,092, filed Apr. 1, 2005 and issued Jul. 15, 2008 as U.S. Pat. No. 7,400,701. The present application, like application Ser. Nos. 12/171,020 and 11/097,092, claims priority to U.S. Provisional Application No. 60/561,079, filed Apr. 9, 2004.
Number | Date | Country | |
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60794295 | Apr 2006 | US | |
60988933 | Nov 2007 | US | |
60561079 | Apr 2004 | US |
Number | Date | Country | |
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Parent | 12272056 | Nov 2008 | US |
Child | 12897197 | US | |
Parent | 11097092 | Apr 2005 | US |
Child | 12171020 | US |
Number | Date | Country | |
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Parent | 11737317 | Apr 2007 | US |
Child | 12272056 | US | |
Parent | 12171020 | Jul 2008 | US |
Child | 11737317 | US |