X-ray scanning with passive radiation detection

Abstract

An X-ray scanning system includes: a housing configured to be handheld; an X-ray source for scanning a target; a set of first detectors configured to be mechanically coupled to the housing and to detect resulting X-rays received from the target responsive to scanning the target; a second detector configured to be mechanically coupled to the housing; and a set of processors mechanically coupled to the housing and communicatively linked to the first detector and to the second detector so as to receive first and second signals, respectively, therefrom. The processor(s) are configured to: generate an image of the target based on the first signal; distinguish, in the second signal, a contribution of passive nuclear radiation detected at the second detector; and provide an output corresponding to the contribution of passive nuclear radiation. A related system for identifying a radioactive isotope, along with corresponding methods, are provided.

Description

X-RAY SCANNING WITH PASSIVE RADIATION DETECTIONRELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No.63 / 745,252, filed on January 14, 2025. The entire teachings of the above application are incorporated herein by reference.TECHNICAL FIELD

[0002] The present invention relates to X-ray scanning systems, and more particularly to X-ray scanning systems that include a capability to detect passive nuclear radiation.BACKGROUND

[0003] X-ray scanning portals, which are used for imaging interior contents of vehicles and other targets, may also include radiation portal monitors (RPMs). RPMs are radiation detectors that are specifically designed to be sensitive to passive nuclear radiation that may be emitted from radioactive material present inside or in vicinity of a target.

[0004] Handheld X-ray scanning systems are also used for imaging interior contents of targets. Handheld X-ray scanning systems typically have X-ray backscatter detectors used for detecting X-ray backscatter to generate the X-ray images. Handheld X-ray scanning systems have previously also included separate detectors that are configured to detect X-ray fluorescence (XRF).SUMMARY

[0005] In existing systems, radiation portal monitors (RPMs) may be situated at a significant distance from any X-ray beam scanning planes in order to minimize any scattered X-rays that result from the active scanning from being detected by the RPMs. Alternatively, specialized shielding arrangements may be used to shield the RPMs from the scattered X-rays.

[0006] In U.S. Patent Nos. 8,325,871 and 9,841,386, both by Grodzins et al. (hereinafter collectively “Grodzins”), there are disclosed mobile and stationary portal X-ray scatter imaging systems with large-area detectors. An X-ray source in the systems emits source X-rays used to scan an object (target) under inspection, and source X-rays are scattered from the object. The large-area detectors are intended to detect scattered X-rays that are backscatteredfrom the object. The large-area detectors are also intended to to detect X-ray fluorescence (XRF) radiation from special nuclear materials, such as U235, that emit characteristic radiation when irradiated with the source X-rays generated by the system’s X-ray source. In addition, the large-area detectors can also be configured to detect passive radiation emissions, emitted from radioactive nuclear materials concealed in the target object, that are not generated in response to any active external X-ray irradiation such as from the X-ray source.

[0007] Because the detectors described by Grodzins are designed to have the dual functions of providing large active areas for detection of scattered X-rays for scatter imaging, while simultaneously being sensitive to detecting XRF and passive nuclear emissions from the target, the detectors cannot include very expensive solid-state detector materials (such as CdTe or CdZnTe), which are typically used for XRF and passive nuclear radiation detection. Solid state detectors are usually chosen for these applications due to their very good energy resolution (e.g., on the order of about 1% at 122keV) and their ability to identify the source of radiation based on the energy of the detected radiation emissions. However, solid state detectors are very expensive. For example, a 5mm x 5mm cadmium telluride (CdTe) detector with electronics may cost approximately $2,500 (as of 2025).

[0008] The Grodzins detectors must instead utilize much less expensive detector materials, such as scintillating phosphor screens (e.g., BaFCl or GOS) or organic plastic or liquid scintillators. These materials typically may cost under $5 per square inch. However, these much less expensive detector materials have very poor energy resolution (approximately 30% - 60%). Consequently, while the Grodzins detectors can be used to detect the presence of elevated radiation levels that may be due to XRF or passive nuclear emissions, they cannot determine respective contributions of XRF, scattered X-rays, passive nuclear radiation, or detector noise. The Grodzins detectors also cannot identify the source of the XRF or the specific radioactive material / isotope that may be present at the target and emitting the passive nuclear radiation.

[0009] Due to the relatively slow response time of most phosphor screens, they are typically too slow to be used in pulse-counting mode. Instead of pulse-counting mode, they must be used in integration mode, in which the individual energies of the detected photons are not measured, and therefore isotope identification is not possible.

[0010] Grodzins, therefore, additionally proposes the use of organic plastic or liquid scintillators composed predominantly of materials of lower atomic number (low-Z), which do have a response time fast enough to measure the energy of the individually detected photons.However, the resulting energy resolution for low-Z detectors is not significantly better than for the scintillating phosphor screens, precluding any unambiguous and reliable radioactive isotope identification. In addition, these organic scintillators are much less effective than the phosphor screen detectors for scatter imaging due to their poor detection of low-energy X-rays below about 120keV. This is because these low-Z organic scintillators rely on detecting incident radiation via the Compton scatter interaction rather than by photoelectric absorption, and the resulting energy deposition in the scintillator for low-energy X-rays is small.

[0011] As described by Grodzins, once the large-area imaging detectors have detected the presence of elevated radiation levels that are not due to irradiation by the active X-ray source in the imaging system, an auxiliary hand-held isotope identifier that uses a solid-state detector must then be used to locate and identify the passive emitting nuclear isotope.

[0012] As previously described, by practical necessity, solid-state detectors must have a small active area, due to their very high cost. This requires that if they are to be used to detect XRF or passive nuclear radiation emissions, they must be positioned close to the target object under inspection, which is most easily achieved with a handheld device.

[0013] Accordingly, there is a need for a single handheld device that can be positioned close to the target object under inspection and can perform both X-ray scanning (e.g., for imaging) and also accurate detection of passive nuclear radiation. It is further desirable for X-ray imaging to be performed simultaneously with the detection of passive nuclear radiation, as well as to include XRF detection and analysis for identification of a wider variety of materials, including non-radioactive materials. In contrast with the Grodzins disclosure, in order to optimize X-ray imaging and detection of XRF and passive nuclear radiation, it would be advantageous for a device to have two sets of detectors: one set of larger scintillation detectors optimized for scatter imaging and / or transmission imaging, and at least one (much smaller) solid-state detector of high energy resolution, optimized for detection and identification of XRF and passive nuclear radiation emissions. It would further be desirable for the imaging detectors to be operable in integration mode (wherein the individual energies of the detected photons are not measured), with the solid-state detector being operable in photon-counting mode (wherein the energy of each detected photon is measured and recorded).

[0014] It has been discovered that passive nuclear radiation and XRF may be analyzed and distinguished from X-ray scatter resulting from active X-ray scanning and imaging.

[0015] In accordance with a first embodiment of the disclosure, an X-ray scanning system includes:a. a housing configured to be handheld;b. an X-ray source disposed within the housing and configured to output a beam of source X-rays for scanning a target;c. a set of first detectors configured to be mechanically coupled to the housing, at least during operation, and to detect resulting X-rays received from the target responsive to the beam of source X-rays scanning the target;d. a second detector configured, at least during operation, to be mechanically coupled to the housing; ande. a set of processors mechanically coupled to the housing and communicatively linked to the first detector and to the second detector so as to receive first and second signals, respectively, therefrom, the set of processors configured to: i. generate an image of the target based on the first signal;ii. distinguish, in the second signal, a contribution of passive nuclear radiation detected at the second detector; andiii. provide an output corresponding to the contribution of passive nuclear radiation.

[0016] In accordance with a second embodiment of the disclosure, a method for X-ray scanning includes:a. outputting, from a housing configured to be handheld, a beam of source X- rays for scanning a target;b. detecting, by a set of first detectors mechanically coupled to the housing, resulting X-rays received from the target responsive to the beam of source X- rays scanning the target;c. generating, at a set of processors mechanically coupled to the housing, an image of the target based on a first signal received from the set of first detectors;d. distinguishing, in a second signal received from a second detector mechanically coupled to the housing, a contribution of passive nuclear radiation detected at the second detector; ande. providing an output corresponding to the contribution of passive nuclearradiation.

[0017] In accordance with a third embodiment of the disclosure, a system for identifying a radioactive material includes:a. a housing configured to be handheld;b. an X-ray source disposed within the housing and configured to output a beam of source X-rays to scan a target;c. a set of detectors configured to be mechanically coupled to the housing, at least during operation, to detect resulting X-rays received from the target responsive to the beam of source X-rays scanning the target, and to detect passive nuclear radiation received from the target; andd. a set of processors configured to:i. generate, based on the resulting X-rays, an image of the target; and ii. provide, based on the detected passive nuclear radiation, an output identifying a radioactive material present at the target.

[0018] In accordance with a fourth embodiment of the disclosure, a method for identifying a radioactive material includes:a. outputting, from a housing configured to be handheld, a beam of source X- rays to scan a target;b. detecting, at a set of detectors mechanically coupled to the housing, (i) resulting X-rays received from the target responsive to the beam of source X- rays scanning the target, and (ii) passive nuclear radiation received from the target,c. generating, based on the detected, resulting X-rays, an image of the target; and d. providing, based on the detected, passive nuclear radiation, an output identifying a radioactive material present at the target.

[0019] In accordance with a fifth embodiment of the disclosure, a non-transitory computer-readable storage medium includes instructions that, when executed by a set of processors, cause the set of processors to perform a method comprising the generating, the distinguishing, and the providing elements according to the second embodiment.

[0020] In accordance with a sixth embodiment of the disclosure, a non-transitory computer-readable storage medium includes instructions that, when executed by a set of processors, cause the set of processors to perform a method for identifying a radioactive material, the method comprising the generating and the providing elements according to the fourth embodiment.BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The foregoing features of embodiments will be more readily understood by reference to the following detailed description, taken with reference to the accompanying drawings. A brief description of the drawings follows.

[0022] FIG. 1 (prior art) is a perspective-view diagram illustrating an example X-ray scanning system for luggage.

[0023] FIG. 2 (prior art) is an illustration of an existing handheld X-ray scanning system incorporating a disk chopper wheel assembly.

[0024] FIG. 3 (prior art) is a perspective-view illustration of a target inspection system that includes a handheld portable X-ray scanner, a coupling arm that includes multiple adjustable joints and a transmission detector module that is rotatably coupled to the coupling arm and is rotatable for selection of resolution of a transmission image.

[0025] FIG. 4 (prior art) is a table that shows radioactive isotopes that are included in the ANSI N42.34 standard.

[0026] FIG. 5 is a cross-sectional diagram illustrating a multi-source X-ray scanning system in form of a vehicle portal with a radiation portal monitor (RPM).

[0027] FIG. 6 is a schematic block diagram illustrating an X-ray imaging system that includes an RPM that can monitor for passive nuclear radiation from a target, without interference from X-rays involved in imaging the target, based on blanking.

[0028] FIG. 7 is a schematic diagram illustrating example blanking (gating) signal flow that may be provided in a multi-source X-ray scanning system such as that of FIG. 5.

[0029] FIG. 8 is an example master timing diagram for an X-ray imaging system having both X-ray scanning and RPM monitoring capabilities, such as that of FIG. 6.

[0030] FIG. 9 is a schematic block diagram illustrating an X-ray scanning system featuring detection of passive nuclear radiation according to an embodiment.

[0031] FIG. 10 is a schematic block diagram illustrating a system for identifying a radioactive material according to an embodiment.

[0032] FIG. 11 A shows the separate contributions to the energy spectrum of photons detected in the second detector from x-ray backscatter and from an Am-241 source present in the target.

[0033] FIG. 1 IB shows the combined energy spectrum of photons detected in the second detector from x-ray backscatter and from an Am-241 source present in the target.

[0034] FIG. 12 shows the energy resolution of a CdTe solid-state detector compared with that of a Nal scintillation detector.

[0035] FIG. 13 shows the K-alpha and K-beta XRF peaks that are emitted from a layer of lead paint on a wood surface when illuminated with a Co-57 source.

[0036] FIG. 14 is a flow diagram illustrating a method for X-ray scanning according to an embodiment.

[0037] FIG. 15 is a flow diagram illustrating a method for identifying a radioactive material according to an embodiment.DETAILED DESCRIPTION

[0038] General Considerations

[0039] The figures and descriptions provided herein may have been simplified to illustrate aspects that are relevant for a clear understanding of the herein described devices, systems, and methods, while eliminating, for the purpose of clarity, other aspects that may be found in typical similar devices, systems, and methods. Those of ordinary skill may recognize that other elements and / or operations may be desirable and / or necessary to implement the devices, systems, and methods described herein. But because such elements and operations are well known in the art, and because they do not facilitate a better understanding of the present disclosure, a discussion of such elements and operations may not be provided herein. However, the present disclosure is deemed to inherently include all such elements, variations, and modifications to the described aspects that would be known to those of ordinary skill in the art.

[0040] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. For example, as used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0041] Although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. That is, terms such as “first,” “second,” and other numerical terms, when used herein, do not imply a sequence or order unless clearly indicated by the context.

[0042] Definitions

[0043] As used in this description and the accompanying claims, the following terms shall have the meanings indicated, unless the context otherwise requires:

[0044] Set” includes at least one member.

[0045] “About,” when used in relation to offsets, separations, or other distances, denotes a tolerance of 10%.

[0046] “Image” refers to an ordered representation of detector signals or representations thereof corresponding to spatial positions. For example, the image may be an array of values within an electronic memory, or, alternatively, a visual image may be formed on a display device such as a video screen or printer.

[0047] Elements Helpful for a Fuller Understanding of Scope of Embodiments and Implementations Thereof

[0048] Referring to FIG. 1 (prior art), a perspective-view diagram is provided, illustrating an existing example X-ray scanning system for luggage. An X-ray scanning system 100 of FIG. 1 exemplifies some basic features of known backscatter imaging systems that output a scanning pencil beam 106 of the source X-rays 110. An X-ray source 102 in this system is a standard X-ray tube, which generates the source X-rays 110. The source X-rays 110 are formed (here, collimated) into a stationary fan beam 138 by a collimation slit aperture in an attenuating plate 140. The stationary fan beam 539 can then be “chopped” into a scanning pencil beam 106 by a disk chopper wheel 142 that defines scanning slit apertures 144 (which may also be referred to herein as “slits”) therein and rotates with a rotation 148. Together, the X-ray source 102, the attenuating plate 140, and the disk chopper wheel 142 form an X-ray beam-forming module 558. In alternative implementations, the source X-rays 110 are formed only into the stationary fan beam 138, which is used to scan over the target directly, without a need for the disk chopper wheel 142.

[0049] The scanning pencil beam 106 thus scans over an article of luggage 108 as the article of luggage 108 moves with the relative motion 112 (travel direction) between the article of luggage 108 and the X-ray source 102. The article of luggage 108 is an example of a target object to be inspected. The relative motion 112 in this diagram is provided by a conveyor 146, which includes a table and a conveyor belt that moves the article of luggage 108 with respect to the source 102.

[0050] The X-ray scanning system 100 can perform transmission X-ray imaging using a transmission X-ray detector 150. X-rays of the scanning pencil beam 106 that interact with the article of luggage 108 (in this case by being transmitted through the article of luggage 108) are detected by the transmission X-ray detector 150. The transmission X-ray detector 150 outputs a detector signal to a monitor 154 via a detector signal cable 152, and the monitor 154 shows a transmission X-ray image 156 of contents of the article of luggage 108.

[0051] The X-ray scanning system 100 can also perform backscatter X-ray imaging using a set of backscatter imaging X-ray detectors (not shown in FIG. 1). The backscatter imaging X-ray detectors may be positioned to detect resultant X-rays that result from the scanning pencil beam 106 interacting with the article of luggage 108 and are scattered by the article of luggage 108 in a general or specific backward direction, such as in a vicinity between the article of luggage 108 and the disk chopper wheel 142. An intensity of the resultant X-rays scattered in the backwards direction may be thus recorded by the set of more backscatter X-ray backscatter detectors (not shown in FIG. 1) as a function of position of the irradiating, scanning pencil beam 106. In the case of backscatter X-ray imaging, it can be advantageous for the backscatter X-ray detectors to be large-area detectors in order to detect the greatest number of X-rays scattered in various specific backward directions. By moving the article of luggage 108 through a scan plane of the pencil scanning beam 106, either on the conveyor 146 or under its own power, a two-dimensional backscatter image of the article of luggage 108 may be obtained.

[0052] Referring to FIG. 2 (prior art), with further reference to FIG. 1, an illustration is provided showing an existing handheld X-ray scanning system 200 that incorporates an X-ray beam-forming module, similar to the X-ray beam-forming module 158 of FIG. 1, with a disk chopper wheel. Components of the handheld X-ray scanning system 200, such as an X-ray tube and a disk chopper wheel, are mounted within a housing 230 of the handheld X-ray scanning system 200. As part of handheld use, the X-ray scanning system 200 can be carriedand moved by a person via handles 257 to scan a vehicle, luggage, or other target flexibly to detect contraband, safety issues, etc.

[0053] As illustrated in FIG. 2, a hand 253 of a person holds the X-ray scanning system 200, in this example via handles 257. The X-ray scanning system 200 is pointed such that a scanning X-ray pencil beam (not illustrated in FIG. 2) is output from the X-ray scanning system 200 during operation and directed toward a vehicle wheel 251. The vehicle wheel 251 is an example of a target (which may also be referred to herein as a “target object,” which can be X-ray scanned for contraband. The X-ray scanning system 200 is configured to produce a real-time image 256 of the vehicle wheel 251.

[0054] Referring to FIG. 3 (prior art), with further reference to FIGs. 1-2, a perspectiveview illustration is provided for a target inspection system that includes a handheld portable X-ray imaging system 300. The system 300 may also be referred to herein as a “scanner” 300 or “imager” 300. A coupling arm is included, which has multiple adjustable joints, and an X-ray transmission detector arm 350 module is rotatably coupled to the coupling arm and is rotatable for selection of resolution of a transmission image.

[0055] The X-ray transmission detector arm 350 in FIG. 3 is attached to the front end of the imager 300 via a coupling arm at only one end in an open-geometry configuration, allowing the object (target, or target object) being scanned to be easily positioned between the imager and the detector as the imager 300 is moved relative to the object during the acquisition of the image. In one implementation, the position of the detector arm that is intercepting the sweeping X-ray beam transmitted through the object can be adjusted relative to the imager at one or more adjustable joints on the coupling arm, allowing smaller or larger objects to be imaged, or to allow objects such as car tires or doors to be imaged. In some applications, it can be advantageous to be able to position the detector arm at an angle with respect to the front face of the X-ray imaging system 300.

[0056] The system 300 shown in FIG. 3 has three adjustable joints on the coupling arm, allowing the detector arm to be aligned with the incident beam, as well as providing enough space between the detector arm 350 and the front of the imager to contain the object being scanned. The coupling arm can be rapidly connected to the X-ray imager 300 via a snapconnection that can provide both mechanical and electrical coupling. Rapid attachability and detachability via connection points such as the snap-connection may be provided on both sides of the X-ray imager 300 as shown in FIG. 3, allowing an operator more flexibility when imaging.

[0057] In some implementations, the X-ray transmission detector arm 350 contains a strip of scintillator (such as scintillating phosphor), and the scintillation light is collected using wavelength-shifting fibers (WSFs). At least one end of the fibers may be coupled to at least one photodetector, such as a photomultiplier tube (PMT). Alternative implementations can use scintillator rods that act as light guides, or hollow light guides lined with reflective material that direct the scintillation light from an enclosed scintillator to photodetectors at one or more ends of the lightguide.

[0058] The X-ray transmission detector arm 350 may be a single-energy detector that produces black and white transmission images. Alternatively, the X-ray transmission detector arm 350 may be a dual-energy detector that provides material identification and from which colorized transmission images may be generated. The X-ray transmission detector arm 350 may be a standard sandwich-type detector that requires two or more stacked scintillator volumes. Alternatively, the X-ray transmission detector arm 350 can provide for dual-energy detection by incorporating a single volume of scintillator optically coupled to two layers of WSFs.

[0059] In implementations, the X-ray transmission detector arm 350 may include one or more lasers mounted on the X-ray imaging system to assist in aligning the active input region of the X-ray transmission detector arm 350 with the incident sweeping beam. The illumination spots of the lasers at each end of the X-ray transmission detector arm 350 may be used to provide feedback cues for adjusting the coupling arm to provide optimal alignment of the beam with the scintillator volume. In other implementations, fiducial markers that are visible in the transmission X-ray image itself are incorporated. The fiducial markers may provide information on a quality of the beam alignment when acquiring a particular X-ray image.

[0060] In implementations, the X-ray transmission detector arm 350 may have at least one spring-loaded coupling that provides some shock protection should the detector strike an object or get stuck when performing a scan. In implementations, a transmission detector kit may included, and the kit may include detector arms of different lengths and which can be advantageously used to scan objects under various conditions and with differing accessibility challenges.

[0061] In implementations, the X-ray transmission detector arm 350 may provide variable resolution along the scan direction (i.e. the direction of relative motion of the imager with respect to the object). The width of the scintillator strip intercepting the transmittedbeam determines the maximum width of the beam that is detected and contributes to the image, and therefore determines the resolution of the transmission image in the scan direction. If the width of the scintillator strip perpendicular to the incident beam direction is smaller than the width of the beam at the point it intercepts the detector, then the image resolution will be defined by the perpendicular width of the scintillator, and not the width of the beam, resulting in higher resolution. If the scintillator strip is wider than the beam, then the image resolution is defined by the width of the beam, resulting in lower resolution. By rotating the X-ray transmission detector arm 350 relative to the incident beam (curved arrow in FIG. 3), the scintillator strip presents a varying width to the incident beam.

[0062] Referring to FIG. 4, a table is provided showing radioactive isotopes that are included in the ANSI N42.34 standard.

[0063] Referring to FIG. 5, with further reference to FIGs. 1-4, a cross-sectional diagram is provided, illustrating a multi-source X-ray scanning system 500 in the form of a vehicle portal. A target (in this case a vehicle 508) passes through the X-ray vehicle scanning portal formed in part by a gantry 590. Various X-ray beam-forming modules 558a positioned around the gantry 590 output source X-rays in the form of scanning pencil beams 106, which are used to provide backscatter X-ray imaging of the vehicle 508. Each scanning pencil beam can have an example beam sweep angle 551. In addition, the X-ray scanning system 500 includes the undercarriage X-ray beam-forming module 558b and an overhead vehicle X-ray beam-forming module 558c, both of which further provide scanning pencil beams 106 that can be used for X-ray backscatter imaging. A side-view vehicle X-ray beam-forming module 558d is also included, is configured to output sources X-rays in the form of a scanning pencil beam, and may have an internal structure similar to that of the X-ray beam-forming modules 558a. Various backscatter imaging X-ray detectors 576 positioned around the gantry 590 are used to capture resultant X-rays (not shown in FIG. 3) that result from the scanning pencil beams 106 interacting with the vehicle 508. The vehicle 508 passes through the gantry 590 with the relative motion 112, which in this view is out of the page, perpendicular to the X and Y axes that are shown.

[0064] The X-ray scanning system 500 further includes an image generator 588 that receives detector signals from the backscatter imaging X-ray detectors 576 and forms X-ray backscatter images of the vehicle 508. All of the scanning pencil beams 106 can also be used for transmission X-ray imaging with appropriately placed transmission X-ray detectors, as isknown in the art of X-ray imaging, similar to the transmission X-ray detector 150 and transmission X-ray imaging function depicted in FIG. 1 using the scanning pencil beam 106.

[0065] The X-ray scanning system 500 further includes the camera system 204a, which is used to detect features of the vehicle 508 to determine when the vehicle 508 is about to intersect with the scanning pencil beams 106. A controller 580 receives a sensing signal 585 from the camera system 204a. In a specific example, the sensing signal 585 may include raw camera images from the camera system 204a, and the controller 580 may analyze the images to complete sensing of the feature(s) of the vehicle 508. In another specific example, an image analysis capability is provided in the camera system 204a, and the sensing signal 585 is simply an ON / OFF indication of whether a particular feature of the vehicle 508 is detected.

[0066] The controller 580, based on the sensed feature, sends a communication command 584 to the communication interface 507, causing the communication interface 507 to output the blanking signal 520. The blanking signal 520 in this implementation is wireless and is received at the radiation portal monitor (RPM) 322b at an opposite side of the gantry 590. Accordingly, in this implementation, the feature sensor (camera system 204a) is operatively coupled to the communication interface 507 indirectly, through the controller 580, as indicated by an operative coupling 518.

[0067] Also illustrated in FIG. 5 is an auxiliary X-ray detector 587 attached to the gantry 590 near the RPM 322b. In an alternative implementation, the camera system 204a, controller 580, and communication interface 507 are not required. Instead, the auxiliary X-ray detector 587 is used solely to detect X-rays scattered from features of the vehicle 508, not for X-ray imaging, and its X-ray detector signal (not shown in FIG. 5) is output to the auxiliary X-ray detector 587. When X-ray detector signal of the auxiliary X-ray detector 587 exceeds a given threshold value, the RPM 322b pauses accumulation of radiation detection data. In an alternative implementation, the auxiliary X-ray detector 587 includes a communication interface and outputs a blanking signal.

[0068] In yet other specific alternative implementations, one of the detectors 576 may be used as a transmission X-ray detector, detecting X-rays that have been transmitted through the vehicle 508. An output signal from the transmission X-ray detector may be used for transmission X-ray imaging, such as by providing its output signal to the image generator 588. Alternatively, the output signal, or a blanking signal based on the output signal, may further be provided to the RPM 322b to pause accumulation of radiation detection data whenthe transmission X-ray detector signal has exceeded a threshold, similar to either of the examples described above for the auxiliary X-ray detector 587.

[0069] Referring to FIG. 6, with further reference to FIGs. 1-5, a schematic block diagram is provided, illustrating an X-ray imaging system 600 that includes a radiation portal monitor (RPM) that can monitor for passive nuclear radiation from a target, without interference from X-rays that are used for imaging the target, based on blanking. The system 600 includes a blanking signal controller 602, which outputs a blanking signal 838 to a first X-ray source 602a, which is a continuous beam X-ray source. As described previously, the first X-ray source 602a is electronically gated having ON and OFF states that may be referred to herein as an activated state and an inactivated state, respectively. The blanking signal controller 602 generates a blanking signal 638a that deactivates the first X-ray source during a blanking period. The first X-ray detector 612a receives the scattered or transmitted X-rays 606 from the target 616.

[0070] An image generator 608 is configured to create one or more images of the target object 616 based on signals 610a from the first X-ray detector 612a. This occurs when the first X-ray source 602a is in the activated state, outputting source X-rays 604. An RPM signal controller 630 controls an RPM 632, which detects any ionizing radiation 606 that is received from the target 616. The ionizing radiation 606 is emitted passively from the target during periods. The RPM signal controller 630 causes the detection to occur, or to be counted, only during periods when the first X-ray source 602a is in the inactivated state The passive ionizing radiation 606 may be considered to be detected, as used herein, when it is based on signals that are output from the RPM 632 only during the blanking period of the first X-ray source 602a, such that the X-rays 604 and 606 do not interfere with detection of the passive ionizing radiation 606. A control signal 638b from the controller 602 to the controller 630 may be the same as, or differ from, the blanking signal 638a, and the logic in the RPM signal controller 630 can respond appropriately to achieve the RPM behavior noted above.Accordingly, interference may be avoided in the RPM detection in a very effective manner, even with the RPM in close proximity to the first X-ray source 602a, X-rays 606, and target 616

[0071] Referring to FIG. 7, with further reference to FIGs. 1-6, a schematic diagram is provided for a master clock blanking signal arrangement for control of a multi-source X-ray scanning system, such as that of FIG. 5. In this example there are five X-ray sources and two RPMs. A master clock module produces an output blanking signal that instructs each of theX-ray sources, which can be installed in multiple lanes, to disable X-rays during the duration of the blanking signal. The same signal is used to instruct the RPMs to acquire data during the duration of the signal, or alternatively to ignore any data that is acquired when the blanking signal is not present.

[0072] Referring to FIG. 8, with further reference to FIGs. 1-7, an example master timing diagram is provided for an X-ray scanning system having both X-ray scanning and RPM monitoring capabilities. FIG. 8 shows example blanking periods that may be used in a system that includes both a set of one or more X-ray scanning modules having electronic gating implemented and a set of one or more RPMs. The master clock module produces regularly spaced blanking signals of duration TBlank. During the time period TBlank, the RPMs can acquire data, and all the X-ray sources are disabled. The blanking pulses are separated by a period of duration TImage. During the period of duration TImage, any X-ray source can be activated if a vehicle is passing through the portal containing the X-ray source. The relative lengths of TBlank and TImage can be selected to minimize the loss in RPM sensitivity, while keeping the reduction in image quality in the X-ray imaging systems at an acceptable level. As an example, a typical backscatter X-ray imaging system will produce one image line per sweep of the beam, with each sweep taking approximately 10 milliseconds. If the blanking time is selected to be 30%, then the blanking pulses will have a duration of TBlank= 3 milliseconds with TImage= 7 milliseconds. This allows no image lines to be completely skipped.

[0073] Example Embodiments

[0074] Referring to FIG. 9, with further reference to FIGs. 1-8, a schematic block diagram is provided, illustrating an X-ray scanning system 900 according to an embodiment of the present disclosure. The X-ray scanning system 900 includes a housing 902, which is configured to be handheld. The X-ray scanning system 900 further includes an X-ray source 904, which is disposed within the housing 902 and is configured to output a beam of source X-rays 906 for scanning a target 908. The X-ray scanning system 900 further includes a set of first detectors 910 and a second detector 914. The set of first detectors 910 is configured to be mechanically coupled to the housing 902, at least during operation, as represented schematically by a mechanical coupling 928. The set of first detectors 910 is further configured to detect resulting X-rays 912 that are received from the target 908 responsive to the beam of source X-rays 906 scanning the target. The second detector 914 is also configured to be mechanically coupled to the housing 902, at least during operation, asrepresented schematically by a mechanical coupling 930. The second detector 914 is further configured to detect passive nuclear radiation 916 that may be received from the target 908.

[0075] The X-ray scanning system 900 also includes a set of processors 916, which is mechanically coupled to the housing 902, as represented by a mechanical coupling 932. The set of processors 916 is communicatively linked to the set of first detectors 910 and to the second detector 914, as represented by a communicative link 918 and a communicative link 920, respectively. The communicative links 918, 920 enable the set of processors to receive first signal 922 and second signal 924, respectively, based on the detected resulting X-rays 912 and on the detected passive nuclear radiation 916, respectively. The set of processors 916 is configured to: generate an image of the target 908 based on the first signal 922; distinguish, in the second signal 924, a contribution of passive nuclear radiation 916 detected at the second detector 914; and provide an output 926 corresponding to the contribution of passive nuclear radiation 916.

[0076] The target 908 may include any item that is desired to be scanned and / or imaged via X-ray scanning, such as the article of luggage 108 of FIG. 1, the vehicle wheel 251 of FIG. 2, the vehicle 508 of FIG. 5, or the target 616 of FIG. 6. The X-ray scanning system 900 can be useful for and applied to other types of targets, such as those with materials to be analyzed via XRF and targets to be monitored for passive nuclear radiation, even if active X-ray scanning is not specifically needed for a purpose of X-ray imaging the target.

[0077] Also or alternatively, the housing 902 may be similar to the housing 230 of FIG.2, for example. The housing 902 may be configured to be handheld by including, optionally, handles attached to or forming part of the housing 902. Example handles 257 are illustrated in FIG. 2. However, a wide variety of alternative form factors are possible, both for the housing 902 and for any optional handles that may facilitate holding the housing by hand.

[0078] Also or alternatively, the X-ray source 904 may form part of an X-ray beamforming module configured to output the beam of source X-rays 906 as a scanning pencil beam of source X-rays. An example X-ray beam-forming module 158 and an example scanning pencil beam of source X-rays 106 are illustrated in FIG. 1.

[0079] Also or alternatively, the output 926 corresponding to the contribution of passive nuclear radiation 916 may include an identification of a radioactive material present at the target 908 (e.g., attached to, carried via, concealed within, concealed by, or dispersed within the target 908). Also, an additional output (not illustrated in FIG. 9) may be provided for theimage of the target 908 generated by the set of processors 916. Also, or alternatively, the output 926 may include a spectrum of the contribution of passive nuclear radiation 916.

[0080] Also or alternatively, the output corresponding to the contribution of passive nuclear radiation may be energy-resolved with an energy resolution equal to or better than about 5 keV. Also, the energy resolution may be equal to or better than about 2 keV. Also, the energy resolution may be equal to or better than about 1 keV. Also, the set of processors 916 may be further configured to execute instructions by which the passive nuclear radiation 916 detected by the second detector 914 is energy-resolved. Various examples of distinguishing the contribution of passive nuclear radiation will be understood in view of the present disclosure, including in examples provided hereinafter in reference to FIGs. 11 A-13.

[0081] Also or alternatively, the second detector 914 may be a cadmium telluride (CdTe) detector, a cadmium zinc telluride (CdZnTe) detector, or a combination of CdTe and CdZnTe detectors. Also or alternatively, multiple second detectors 914 may be provided and may optionally be communicatively linked such that individual output signals therefrom are either input separately to the set of processors 916 or combined together for a single second signal 924 for input to the set of processors 916.

[0082] The first signal 922 and second signal 924 are digital signals that result directly or indirectly from output of the set of first detectors 910 and the second detector 914, respectively. In one implementation, direct output of the detectors may be analog, and the communicative lines 918, 920 may include any necessary intermediary components necessary for the set of processors 916 to receive the digital signals, as will be understood by those of skill in the art. For example, the communicative lines 918, 920 may include analog-to-digital (A / D) converters, computer buses, wired signal connections, and / or wireless signal connections, and / or other intermediary system components, whether inside or external to the detectors 910, 914.

[0083] Also or alternatively, the set of processors 916 may be configured to effect a concurrent accumulation of data based on the set of first detectors 910 and based on the second detector 914. Also or alternatively, the set of processors 916 may be configured to effect a pause in accumulation of data based on the second detector 914 when the X-ray source 904 is in an ON state so as to output the beam of source X-rays 906 toward the target 908.

[0084] The set of first detectors 910 may be configured to be mechanically decoupled from the housing 902 during time periods when the system is not in operation (e.g., when theX-ray source 904 is set to an <OFF> state such that the beam of source X-rays 906 is not output). In one implementation, the set of first detectors 910 includes the detector arm for detecting transmission X-rays, as illustrated in in FIG. 3. As also illustrated in FIG. 3, the detector arm may be mechanically coupled to the housing by means of a coupling arm, adjustable joints, a connection point to the housing, and the like.

[0085] Also or alternatively, the second detector 914 may be configured to be mechanically decoupled from the housing 902 during time periods when the system is not in operation, similar to the set of first detectors 910. In one implementation, the second detector is mechanically coupled directly or indirectly to the set of first detectors 910 (e.g., the detector arm for detecting transmission X-rays, as illustrated in FIG. 3 and described above in connection with FIG. 9). In other implementations, the set of first detectors 910, the second detector 914, or both may be semi-permanently mounted directly onto or within the housing 910.

[0086] Also or alternatively, the set of processors may be further configured to:a. distinguish, from the second signal 924, a contribution of X-ray fluorescence (XRF) detected at a detector selected from the group consisting of the second detector 914, a third detector (not illustrated in FIG. 9), and combinations thereof; andb. provide an output (not illustrated in FIG. 9) corresponding to the contribution of XRF.

[0087] The second detector 914 may be further configured to detect both the XRF and the passive nuclear radiation 916. As part of the function of the set of processors 916, distinguishing the contribution of the passive nuclear radiation 916 may include distinguishing from a contribution of the XRF detected. The set of processors 916 may identify a material present at the target 908 based on the contribution of the XRF. As will be understood, the set of processors 916 may, accordingly, output the identification of the material based on the contribution of XRF. Materials identified by XRF may include nonradioactive materials, such as lead, and precious metals, such as gold and platinum. Various examples of distinguishing the contribution of passive nuclear radiation will be understood in view of the present disclosure, including in examples provided hereinafter in reference to FIGs. 11A-13.

[0088] The X-ray scanning system 900 may further include a display mounted to the housing 902. The display may be communicatively linked to the set of processors 916. Thedisplay may be configured to show items of information such as a graphical rendering of the image of the target 908, the output corresponding to the passive nuclear radiation 916, the output corresponding to the contribution of XRF, or any combination of these items of information. The image may include a scatter X-ray image, a transmission X-ray image, a composite image, a visible light image, an infrared (IR) image, or any combination of these. The image(s) may be selectable based on options available via buttons on the housing 902 or available via a graphical user interface shown on the display. The data based on the passive nuclear radiation 916 may include a spectrum of the passive nuclear radiation 916, identification of a set of one or more radioactive isotopes identified based on the spectrum, and the like. Additional or alternative information may be shown on the display, such as identification of a material in, on, or of the target 908 based on the X-ray image, XRF detected during a scan, the data based on the passive nuclear radiation 916, or a combination of these.

[0089] FIG. 10 is a schematic block diagram illustrating a system for identifying a radioactive material 1000 according to an embodiment. FIG. 10 is similar to the system 900 of FIG. 9, with some exceptions noted hereinafter. FIG. 10 includes a set of processors 1016 configured to generate, based on the resulting X-rays 912, an image of the target. The set of processors 1016 is further configured to provide, based on the detected passive nuclear radiation 916, an output 1026 specifically identifying a radioactive material present at the target 908. Since the output 1026 specifically identifies the radioactive material, it will be understood that in this aspect, system 1000 may be considered a specific implementation of the system 900 of FIG. 9. As described above, in system 900, the output 926 corresponding to the contribution of passive nuclear radiation 916 may include an identification of a radioactive material present at the target 908.

[0090] In another aspect, system 1000 is more generalized than system 900, in that the communicative links 918, 920 and signals 922, 924 are not specified in system 1000. Instead, as indicated above, in system 1000, the image is based on the resulting X-rays 912, which may have been scattered from or transmitted through the target 908. In view of the present disclosure, a person skilled in the art of X-ray imaging will understand various ways in which this image may be based on the resulting X-rays 912. Furthermore, the set of processors 1016 is configured to provide, based on the detected passive nuclear radiation 916, the output 1026 specifying the identified radioactive material. In view of the present disclosure, a personskilled in the art of X-ray imaging and passive radiation detection will understand various ways in which this may be accomplished.

[0091] In all aspects, the embodiment of FIG. 10 may be further understood to be able incorporate elements of any of the other embodiments described herein, including FIG. 9. In various implementations, this embodiment may include any of the elements of other embodiments described herein, as will be recognized consistent with the accompanying claims and drawings, in addition to the description.

[0092] FIG. 11 A shows the separate contributions to the energy spectrum of photons detected in the second detector from X-ray backscatter and from an Am-241 source present in the target.

[0093] FIG. 1 IB shows the combined energy spectrum of photons detected in the second detector from x-ray backscatter and from an Am-241 source present in the target.

[0094] FIG. 12 shows the energy resolution of a CdTe solid-state detector compared with that of a Nal scintillation detector.

[0095] FIG. 13 shows the K-alpha and K-beta XRF peaks that are emitted from a layer of lead paint on a wood surface when illuminated with a Co-57 source.

[0096] Referring further to FIGs. 1-13, and more especially to FIGs. 9-10, distinguishing the passive nuclear radiation component in the second signal 924 of FIG. 9 may typically involve identifying at least one characteristic peak of radiation that is superimposed on any X-ray background incident on the second detector 914. For example, in the simulated energy spectrum shown in FIG. 11 A, a main peak 1170 resulting from the passive radioactive decay of Am-241 (passive nuclear radiation) has an energy of 59.5 keV (solid line). The detected X-ray backscatter spectrum 1172 from a 160kV X-ray beam (source X-rays) incident on a bag full of clothing (target) is shown with the dashed line. The Am-241 peak 1170 therefore lies on a shoulder 1174 of the backscatter spectrum 1172 in the combined spectrum, as shown in FIG. 11B.

[0097] In one example, to isolate and identify the peak 1170, the underlying background 1172 in the energy spectrum may be first fit with a polynomial function, and a Gaussian peak with a centroid located at 59.5keV may be fit to the residual counts that lie above the background polynomial. If the residual counts are considered by the detection algorithm to be statistically significant, then an output indicating the presence of Am-241 can be generated.

[0098] A decision as to whether an identified peak is statistically significant may typically involve comparing total counts in the peak 1170 to the expected uncertainty in thenumber of counts contained in the background 1172 under the peak 1174. Since the detection process for X-rays is governed by Poisson statistics, an expected one-sigma uncertainty in the background is equal to the square root of the number of background counts under the peak. A detection threshold may be set to determine whether an isotope has been detected. For example, if the threshold is set to three-sigma, then there must be at least three times the number of counts in the peak 1170 above the background compared to the counts under the peak 1170 in the background 1172.

[0099] For a comprehensive radiation detection system, a library of common radioactive isotopes is used to allow a set of processors running software to detect the presence of passive radiation emissions at many different points on the energy spectrum, from many different isotopes. For each of the isotopes in the library, the process described above may be repeated, with the peak centroids located at the energies stored in a lookup table. A list of common industrial and medical isotopes, along with some radioactive special nuclear materials that are listed in the ANSI N42.34 standard, are shown in FIG. 4.

[0100] A process for detecting and identifying XRF may be similar to the process for passive nuclear radiation detection, except that the data should be acquired with the source X-rays irradiating the target object, and twin Gaussian peaks should be fitted, rather than single Gaussian peaks at the energy of interest. A detection and identification of lead (Pb) XRF peaks above a backscatter spectrum of a lead paint analyzer with a Co-57 radioactive source is shown in FIG. 13 by way of example. In the case of lead fluorescence, twin Gaussian peaks are fitted to the residual counts above the fitted background at an energy of 75keV. These peaks capture the lead K-alpha and K-beta fluorescence. The size of the peaks can be used to determine an amount of lead present in the paint (target) being analyzed.

[0101] A major advantage of using a solid-state material instead of a scintillation material for the second detector 914 is shown in FIG. 12. In this example, the primary peak for Am-241 is shown when a CdTe solid-state detector with 1.5% energy resolution is used as the second detector material, compared to the case where a Nal scintillator detector with 18% energy resolution is used. It will be readily apparent in view of this disclosure that the passive radiation peak can be detected above the underlying background with much higher sensitivity for the CdTe detector than for the Nal detector.

[0102] FIG. 14 is a flow diagram illustrating a method for X-ray scanning according to an embodiment. At stage 1410, from a housing configured to be handheld, a beam of source X-rays is output for scanning a target. At stage 1420, by a set of first detectors mechanicallycoupled to the housing, resulting X-rays received from the target responsive to the beam of source X-rays scanning the target are detected. At stage 1430, at a set of processors mechanically coupled to the housing, an image of the target is generated, based on a first signal received from the set of first detectors. At stage 1440, in a second signal received from a second detector mechanically coupled to the housing, a contribution of passive nuclear radiation detected at the second detector is distinguished. At stage 1450, an output corresponding to the contribution of passive nuclear radiation is provided.

[0103] The method illustrated in FIG. 14 may be modified and / or amplified to include other stages consistent with the description and elements of any of FIGs. 9-13.

[0104] FIG. 15 is a flow diagram illustrating a method for identifying a radioactive material according to an embodiment. The method includes at least the following stages. At stage 1510, from a housing configured to be handheld, a beam of source X-rays is output to scan a target. At stage 1520, at a set of detectors mechanically coupled to the housing, the following are detected: (i) resulting X-rays received from the target responsive to the beam of source X-rays scanning the target, and (ii) passive nuclear radiation received from the target. At stage 1530, based on the detected, resulting X-rays, an image of the target is generated. At stage 1540, based on the detected, passive nuclear radiation, an output is provided, identifying a radioactive material present at the target.

[0105] The method illustrated in FIG. 15 may be modified and / or amplified to include other stages consistent with the description and elements of any of FIGs. 9-13.

[0106] In a further embodiment, a non-transitory computer-readable storage medium includes instructions that, when executed by a set of processors, cause the set of processors to perform a method comprising the generating, the distinguishing, and the providing elements according to the embodiment method illustrated in FIG. 14.

[0107] The instructions may be modified and / or amplified to include other stages consistent with any of the embodiment methods described herein.

[0108] In a further embodiment, a non-transitory computer-readable storage medium includes instructions that, when executed by a set of processors, cause the set of processors to perform a method for identifying a radioactive material, the method comprising the generating and the providing elements according to FIG. 15.

[0109] The instructions may be modified and / or amplified to include other stages consistent with any of the embodiment methods described herein.

[0110] In various implementations, features described in connection with FIGs. 9-15 may be implemented within systems described in connection with FIGs. 1, 2, 3, 5, and 6, for example.

[0111] Implementation Examples

[0112] Implementation examples are provided in the following numbered clauses. The numbered clauses represent some embodiments of the present invention and potential claims. (The actual claims are provided at the end of this application.) These clauses form a part of the written description of this application. Accordingly, subject matter of the following clauses may be presented as claims in later proceedings involving this application or any application claiming priority based on this application. Inclusion of such clauses should not be construed to mean that the claims do not cover the subject matter of the clauses. Thus, a decision not to present these clauses as claims in later proceedings should not be construed as a donation of the subject matter to the public.

[0113] Without limitation, potential subject matter that may be claimed includes:

[0114] Clause 1. An X-ray scanning system comprising:a. a housing configured to be handheld;b. an X-ray source disposed within the housing and configured to output a beam of source X-rays for scanning a target;c. a set of first detectors configured to be mechanically coupled to the housing, at least during operation, and to detect resulting X-rays received from the target responsive to the beam of source X-rays scanning the target;d. a second detector configured, at least during operation, to be mechanically coupled to the housing; ande. a set of processors mechanically coupled to the housing and communicatively linked to the first detector and to the second detector so as to receive first and second signals, respectively, therefrom, the set of processors configured to: i. generate an image of the target based on the first signal;ii. distinguish, in the second signal, a contribution of passive nuclear radiation detected at the second detector; andiii. provide an output corresponding to the contribution of passive nuclear radiation.

[0115] Clause 2. The X-ray scanning system of clause 1, the X-ray source forming part of an X-ray beam-forming module configured to output the beam of source X-rays as a scanning pencil beam of source X-rays.

[0116] Clause 3. The X-ray scanning system of clause 1 or clause 2, wherein the output corresponding to the contribution of passive nuclear radiation includes an identification of a radioactive material present at the target.

[0117] Clause 4. The X-ray scanning system of any of clauses 1-3, wherein the output includes a spectrum of the contribution of passive nuclear radiation.

[0118] Clause 5. The X-ray scanning system of any of clauses 1-4, wherein the output corresponding to the contribution of passive nuclear radiation is energy-resolved with an energy resolution equal to or better than about 5 keV.

[0119] Clause 6. The X-ray scanning system of clause 5, wherein the energy resolution is equal to or better than about 2 keV.

[0120] Clause 7. The X-ray scanning system of clause 6, wherein the energy resolution is equal to or better than about 1 keV.

[0121] Clause 8. The X-ray scanning system of any of clauses 1-7, wherein the second detector is selected from the group consisting of a cadmium telluride (CdTe) detector, a cadmium zinc telluride (CdZnTe) detector, and combinations thereof.

[0122] Clause 9. Clause 1. The X-ray scanning system of any of clauses 1-8, wherein the set of processors is configured to effect a concurrent accumulation of data based on the set of first detectors and on the second detector.

[0123] Clause 10. The X-ray scanning system of any of clauses 1-9, wherein the set of processors is configured to effect a pause in accumulation of data from the second detector when the system is in an ON state defined by the source X-rays being output from the X-ray scanning system toward the target.

[0124] Clause 11. The X-ray scanning system of any of clauses 1-9, wherein the set of processors is further configured to:a. distinguish, from the second signal, a contribution of X-ray fluorescence (XRF) detected at a detector selected from the group consisting of the second detector, a third detector, and combinations thereof; andb. provide an output corresponding to the contribution of XRF.

[0125] Clause 12. The X-ray scanning system of clause 11, wherein the output corresponding to the contribution of XRF includes an identification of a material present at the target based on the contribution of XRF.

[0126] Clause 13. The X-ray scanning system of any of clauses 1-12, further comprising a display mounted to the housing and communicatively linked to the set of processors, the display configured to show information selected from the group consisting of a graphical rendering of the image of the target, the output corresponding to the contribution of passive nuclear radiation, the output corresponding to the contribution of XRF according to clause 11 or clause 12, and combinations thereof.

[0127] Clause 14. A method for X-ray scanning, the method comprising:a. outputting, from a housing configured to be handheld, a beam of source X- rays for scanning a target;b. detecting, by a set of first detectors mechanically coupled to the housing, resulting X-rays received from the target responsive to the beam of source X- rays scanning the target;c. generating, at a set of processors mechanically coupled to the housing, an image of the target based on a first signal received from the set of first detectors;d. distinguishing, in a second signal received from a second detector mechanically coupled to the housing, a contribution of passive nuclear radiation detected at the second detector; ande. providing an output corresponding to the contribution of passive nuclear radiation.

[0128] Clause 15. The method for X-ray scanning according to clause 14, further including and / or utilizing any of the elements of any of clauses 1-13.

[0129] Clause 16. A system for identifying a radioactive material, the system comprising:a. a housing configured to be handheld;b. an X-ray source disposed within the housing and configured to output a beam of source X-rays to scan a target;c. a set of detectors configured to be mechanically coupled to the housing, at least during operation, to detect resulting X-rays received from the target responsive to the beam of source X-rays scanning the target, and to detect passive nuclear radiation received from the target; andd. a set of processors configured to:i. generate, based on the resulting X-rays, an image of the target; and ii. provide, based on the detected passive nuclear radiation, an output identifying a radioactive material present at the target.

[0130] Clause 17. The system for identifying a radioactive material according to clause 16, further and / or utilizing any of the elements of any of clauses 1-13.

[0131] Clause 18. A method for identifying a radioactive material, the method comprising:a. outputting, from a housing configured to be handheld, a beam of source X- rays to scan a target;b. detecting, at a set of detectors mechanically coupled to the housing, (i) resulting X-rays received from the target responsive to the beam of source X- rays scanning the target, and (ii) passive nuclear radiation received from the target;c. generating, based on the detected, resulting X-rays, an image of the target; and d. providing, based on the detected, passive nuclear radiation, an output identifying a radioactive material present at the target.

[0132] Clause 19. A method for identifying a radioactive material according to clause 18, further including and / or utilizing any of the elements of any of clauses 1-13.

[0133] Clause 20. A non-transitory computer-readable storage medium including instructions that, when executed by a set of processors, cause the set of processors to perform a method comprising the generating, the distinguishing, and the providing elements according to clause 14 or clause 15.

[0134] Clause 21. A non-transitory computer-readable storage medium including instructions that, when executed by a set of processors, cause the set of processors to perform a method for identifying a radioactive material, the method comprising the generating and the providing elements according to clause 18 or clause 19.

[0135] Other Considerations

[0136] The embodiments of the invention described above are intended to be merely exemplary. In view of the present description and drawings, numerous variations, modifications, and combinations of parameters are possible. All such variations and modifications are intended to be within the scope of the present invention as defined in anyappended claims. Those variations, modifications, and combinations of parameters described herein are examples for purposes of explanation only.

[0137] As used herein, the singular forms “a,” “an,” and “the” include the plural forms as well, unless the context clearly indicates otherwise. Thus, reference to a device in the singular (e.g., “a device,” “the device”), including in the claims, includes one or more of such devices (e.g., “a processor” includes one or more processors, “the processor” includes one or more processors, “a memory” includes one or more memories, “the memory” includes one or more memories, etc.). The terms “comprises,” “comprising,” “includes,” and / or “including,” as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0138] Also, as used herein, “or” as used in a list of items (possibly prefaced by “at least one of’ or prefaced by “one or more of’) indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C,” or a list of “one or more of A, B, or C” or a list of “A or B or C” means A, or B, or C, or AB (A and B), or AC (A and C), or BC (B and C), or ABC (i.e., A and B and C), or combinations with more than one feature (e.g., AA, AAB, ABBC, etc.). Thus, a recitation that an item, e.g., a processor, is configured to perform a function regarding at least one of A or B, or a recitation that an item is configured to perform a function A or a function B, means that the item may be configured to perform the function regarding A, or may be configured to perform the function regarding B, or may be configured to perform the function regarding A and B. For example, a phrase of “a processor configured to measure at least one of A or B” or “a processor configured to measure A or measure B” means that the processor may be configured to measure A (and may or may not be configured to measure B), or may be configured to measure B (and may or may not be configured to measure A), or may be configured to measure A and measure B (and may be configured to select which, or both, of A and B to measure).

[0139] As used herein, unless otherwise stated, a statement that a function, operation, signal, or other item is “based on” an item or condition means that the function or operation is based on the stated item or condition and may be based on one or more items and / or conditions in addition to the stated item or condition.

[0140] Generally speaking, a computer-readable medium may include any tangible or non-transitory storage media or memory media such as electronic, magnetic, or optical media — e.g., disk or CD / DVD-ROM coupled to computer system via a bus. The terms“tangible” and “non-transitory,” as used herein, are intended to describe a computer-readable storage medium (or “memory”) excluding propagating electromagnetic signals, but are not intended to limit otherwise the type of physical computer-readable storage device that is encompassed by the phrase computer-readable medium or memory. For instance, the terms “non-transitory computer-readable medium” or “tangible memory” are intended to encompass types of storage devices that do not necessarily store information permanently, including for example, random access memory (RAM). Program instructions and data stored on a tangible computer-accessible storage medium in non-transitory form may further be transmitted by transmission media or signals such as electrical, electromagnetic, or digital signals, which may be conveyed via a communication medium such as a network and / or a wireless link.

[0141] The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

Claims

CLAIMSWhat is claimed is:

1. An X-ray scanning system comprising:a housing configured to be handheld;an X-ray source disposed within the housing and configured to output a beam of source X-rays for scanning a target;a set of first detectors configured to be mechanically coupled to the housing, at least during operation, and to detect resulting X-rays received from the target responsive to the beam of source X-rays scanning the target;a second detector configured, at least during operation, to be mechanically coupled to the housing; anda set of processors mechanically coupled to the housing and communicatively linked to the first detector and to the second detector so as to receive first and second signals, respectively, therefrom, the set of processors configured to:generate an image of the target based on the first signal; distinguish, in the second signal, a contribution of passive nuclear radiation detected at the second detector; andprovide an output corresponding to the contribution of passive nuclear radiation.

2. The X-ray scanning system of claim 1, the X-ray source forming part of an X-ray beam-forming module configured to output the beam of source X-rays as a scanning pencil beam of source X-rays.

3. The X-ray scanning system of claim 1 or claim 2, wherein the output corresponding to the contribution of passive nuclear radiation includes an identification of a radioactive material present at the target.

4. The X-ray scanning system of any of claims 1-3, wherein the output includes a spectrum of the contribution of passive nuclear radiation.

5. The X-ray scanning system of any of claims 1-4, wherein the output corresponding to the contribution of passive nuclear radiation is energy-resolved with an energy resolution equal to or better than about 5 keV.

6. The X-ray scanning system of claim 5, wherein the energy resolution is equal to or better than about 2 keV.

7. The X-ray scanning system of claim 6, wherein the energy resolution is equal to or better than about 1 keV.

8. The X-ray scanning system of any of claims 1-7, wherein the second detector is selected from the group consisting of a cadmium telluride (CdTe) detector, a cadmium zinc telluride (CdZnTe) detector, and combinations thereof.

9. The X-ray scanning system of any of claims 1-8, wherein the set of processors is configured to effect a concurrent accumulation of data based on the set of first detectors and on the second detector.

10. The X-ray scanning system of any of claims 1-9, wherein the set of processors is configured to effect a pause in accumulation of data from the second detector when the system is in an ON state defined by the source X-rays being output from the X-ray scanning system toward the target.

11. The X-ray scanning system of any of claims 1-9, wherein the set of processors is further configured to:distinguish, from the second signal, a contribution of X-ray fluorescence (XRF) detected at a detector selected from the group consisting of the second detector, a third detector, and combinations thereof; andprovide an output corresponding to the contribution of XRF.

12. The X-ray scanning system of claim 11, wherein the output corresponding to the contribution of XRF includes an identification of a material present at the target based on the contribution of XRF.

13. The X-ray scanning system of any of claims 1-12, further comprising a display mounted to the housing and communicatively linked to the set of processors, the display configured to show information selected from the group consisting of agraphical rendering of the image of the target, the output corresponding to the contribution of passive nuclear radiation, the output corresponding to the contribution of XRF according to claim 11 or claim 12, and combinations thereof.

14. A method for X-ray scanning, the method comprising:outputting, from a housing configured to be handheld, a beam of source X- rays for scanning a target;detecting, by a set of first detectors mechanically coupled to the housing, resulting X-rays received from the target responsive to the beam of source X-rays scanning the target;generating, at a set of processors mechanically coupled to the housing, an image of the target based on a first signal received from the set of first detectors; distinguishing, in a second signal received from a second detector mechanically coupled to the housing, a contribution of passive nuclear radiation detected at the second detector; andproviding an output corresponding to the contribution of passive nuclear radiation.

15. The method for X-ray scanning according to claim 14, further including and / or utilizing any of the elements of any of claims 1-13.

16. A system for identifying a radioactive material, the system comprising:a housing configured to be handheld;an X-ray source disposed within the housing and configured to output a beam of source X-rays to scan a target;a set of detectors configured to be mechanically coupled to the housing, at least during operation, to detect resulting X-rays received from the target responsive to the beam of source X-rays scanning the target, and to detect passive nuclear radiation received from the target; anda set of processors configured to:generate, based on the resulting X-rays, an image of the target; and provide, based on the detected passive nuclear radiation, an output identifying a radioactive material present at the target.

17. The system for identifying a radioactive material according to claim 16, further including and / or utilizing any of the elements of any of claims 1-13.

18. A method for identifying a radioactive material, the method comprising:outputting, from a housing configured to be handheld, a beam of source X- rays to scan a target;detecting, at a set of detectors mechanically coupled to the housing, (i) resulting X-rays received from the target responsive to the beam of source X-rays scanning the target, and (ii) passive nuclear radiation received from the target;generating, based on the detected, resulting X-rays, an image of the target; and providing, based on the detected, passive nuclear radiation, an output identifying a radioactive material present at the target.

19. A method for identifying a radioactive material according to claim 18, further including and / or utilizing any of the elements of any of claims 1-13.

20. A non-transitory computer-readable storage medium including instructions that, when executed by a set of processors, cause the set of processors to perform a method comprising the generating, the distinguishing, and the providing elements according to claim 14 or claim 15.

21. A non-transitory computer-readable storage medium including instructions that, when executed by a set of processors, cause the set of processors to perform a method for identifying a radioactive material, the method comprising the generating and the providing elements according to claim 18 or claim 19.

Images