Systems and methods for non-invasive screening of individuals - Patents.com

Abstract

The systems and methods described herein provide a system for scanning an individual to identify concealed objects carried by the individual. The systems and methods use an imaging mast having a transmitter and a receiver of electromagnetic radiation. The first and second imaging masts transmit and receive radiation on first and second scan paths, respectively, centered on a central point. The first and second scan paths are in a mirror image arrangement with respect to the central point. The geometry of the scan paths of the imaging masts allows for the use of multistatic reconstruction algorithms and improved data acquisition compared to conventional systems and methods.

Description

[Technical field]

[0001] Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 323,840, filed March 25, 2022, which is incorporated by reference in its entirety. [Background technology]

[0002] Contactless screening is an important tool for detecting the presence of contraband or dangerous items carried by individuals entering restricted areas or transportation hubs such as secured buildings, airports, or train stations. A variety of technologies are used for contactless screening, including X-ray and millimeter wave imaging. Such technologies can be used to produce images that reveal hidden objects carried by a person that are not visible at first glance. Summary of the Invention [Means for solving the problem]

[0003] A scanning system is presented. The scanning system includes a first imaging mast including a first plurality of electromagnetic radiation transmitters and a first plurality of electromagnetic radiation receivers. The first imaging mast is configured to move through a first side of an object disposed along a central horizontal axis to image at least a first portion of the object. The scanning system includes a second imaging mast including a second plurality of electromagnetic radiation transmitters and a second plurality of electromagnetic radiation receivers. The second imaging mast is configured to move through a second side of the object to image at least a second portion of the object. The first imaging mast and the second imaging mast are configured to move in unison in a common horizontal direction relative to the central horizontal axis. The scanning system includes a computing device including a processing unit. The computing device is configured to execute instructions to receive imaging data from the first imaging mast, the second imaging mast, or both imaging masts. The imaging data represents electronic radiation reflected or scattered by the object as the first imaging mast and the second imaging mast move through the object. The computing device is configured to execute instructions to apply a reconstruction algorithm to the imaging data to generate an image of at least a portion of the object.

[0004] A method of scanning an object is presented. The method includes transmitting electronic radiation from one of a plurality of transmitters of a first imaging mast or a second imaging mast. The method includes receiving imaging data at a computing device indicative of reception of electromagnetic radiation scattered or reflected from the object by a plurality of first receivers of the first imaging mast and a plurality of second receivers of the second imaging mast. The method includes moving the first imaging mast and the second imaging mast in unison in a common horizontal direction relative to a central horizontal axis. The method includes reconstructing an image of the object by applying a multistatic reconstruction algorithm of the computing device to the imaging data.

[0005] Exemplary embodiments are illustrated in the accompanying drawings by way of example and are not to be considered as limitations of the present disclosure. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 shows a schematic top view of a prior art system for screening individuals to detect concealed objects; [Diagram 2] FIG. 1A is a schematic diagram illustrating a top view of a millimeter wave scanning system for screening individuals to detect hidden objects using motion of a cylindrical mast, according to some embodiments described herein. [Diagram 3] FIG. 2A is a schematic diagram illustrating a top view of electromagnetic radiation transmission and reception on the same mast according to some embodiments described herein. [Figure 4] FIG. 2A is a schematic diagram illustrating a top view of the transmission of electromagnetic radiation from a first mast and the reception of electromagnetic radiation at a second mast according to some embodiments described herein. [Diagram 5] FIG. 1A is a schematic diagram illustrating a top view of a millimeter wave scanning system for screening individuals to detect hidden objects using linear mast motion, according to some embodiments described herein. [Figure 6A] 1A-1C are schematic diagrams illustrating a motion sequence of a linearly moving mast that undergoes rotation during movement, according to some embodiments described herein. [Figure 6B] 1A-1C are schematic diagrams illustrating a motion sequence of a linearly moving mast that undergoes rotation during movement, according to some embodiments described herein. [Figure 6C] 1A-1C are schematic diagrams illustrating a motion sequence of a linearly moving mast that undergoes rotation during movement, according to some embodiments described herein. [Figure 7] FIG. 1A is a schematic diagram illustrating a top view of a millimeter wave scanning system for screening individuals to detect concealed objects, including a non-translating mast and a reflector, according to some embodiments described herein. [Figure 8A] FIG. 1 is a perspective view of an imaging mast for use in some embodiments of the systems and methods of the present disclosure. [Figure 8B] FIG. 2 is a front view of an imaging mast for use in some embodiments of the systems and methods of the present disclosure. [Figure 9] FIG. 1 illustrates a schematic diagram of a non-invasive walk-through metal detector for use in some embodiments of the systems and methods of the present disclosure. [Figure 10] FIG. 1 illustrates a schematic diagram of a computing device for use in some embodiments described herein. [Figure 11] FIG. 1 illustrates a schematic diagram of a network environment for use with the systems and methods of some embodiments described herein. [Figure 12] FIG. 1 illustrates a method for scanning an individual to detect hidden objects using an embodiment of the system described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Described in detail herein are systems and methods for non-invasive step-through screening of individuals for contraband. The systems and methods use a full-body imaging system configured to improve the scanning experience for users while providing rapid throughput of the entire individual. A high scan throughput is desirable to reduce the wait time of individuals waiting to be screened. In a conventional imaging system, an individual enters a room and faces a side direction perpendicular to the entrance and exit directions. The individual must place their hands on their head and hold them in a stationary position for a period of time while the imaging scanner moves to cover multiple viewing angles around the individual. The individual can then lower their hands, turn to the exit, and exit the room. This multi-step process must be conveyed to each screened individual, and the time to complete an individual scan can be increased if the individual requires additional assistance or re-direction.

[0008] The disclosed system and method improves the user experience by allowing an individual to walk into a room and continue facing in a forward direction (e.g., toward an exit) throughout the entire operation process. The imaging mast transmits and receives electromagnetic radiation on a scan path that is mirrored across the person. This arrangement of the scan path allows for cross-mast transmission and reception, enabling powerful multistatic reconstruction algorithms. The increased amount of imaging data over a greater variety of scattering angles in the disclosed system allows for scanning of forward-facing individuals, larger rooms with wider entrances and exits to accommodate individuals with impaired mobility, and greater throughput due to the ability to make the scan path shorter given the increased data throughput.

[0009] As used herein, a "scan path" is a trajectory through a collection of points from which electromagnetic radiation is directed to an object (such as an individual) to be imaged, or along which electromagnetic radiation is reflected or scattered from an object to be imaged. In some embodiments, the scan path can be physically traced by the motion of a transmitter or receiver of electromagnetic radiation. In other embodiments, the scan path is a trajectory through a collection of points that represent virtual or apparent transmitters or receivers of electromagnetic radiation (i.e., points along a surface of a reflector that all focus on a common transmitter or receiver).

[0010] FIG. 1 shows a top view of a prior art system 10 for imaging an individual according to a conventional concept. The individual enters the imaging room 11 in a forward direction 17 through the entrance 14 and stands at or near the center point 16 of the room. The center point 16 can be indicated using an instruction marking 13 to help the individual understand how to stand for scanning purposes, such as a footprint mark. The individual faces in a direction perpendicular to an axis connecting the entrance 14 and the exit 15 of the room 11. In other words, the individual turns 90°, often to the right, to face a lateral direction 28. The individual places his or her hands on top of his or her head. Once the individual is in the scanning position, the two imaging masts 12 rotate around the individual on a scanning path 25, as indicated by the arrows in FIG. 1.

[0011] Conventionally, the imaging masts 12 are connected in a "tuning fork"-like configuration to a rigid central mount located on the ceiling of the room 11. The two imaging masts 12 are rigidly connected so that both rotate in the same direction, e.g., clockwise or counterclockwise, and maintain a constant separation distance between them. The imaging masts include both transmitters 18 and receivers 19. Each receiver 19 is spatially associated with a transmitter 18, such as by being located in close proximity, to form or function as a single-point transmitter / receiver. In operation, the transmitters 18 sequentially transmit electromagnetic radiation, one at a time, that is reflected or scattered from an individual, and the reflected or scattered electromagnetic radiation is received by two of the respective receivers 19. A computing device receives signals from the receivers 19 and reconstructs an image of the individual using monostatic reconstruction techniques. Concealed objects or contraband may be visible on the image because the density or other material properties of the concealed objects differ from organic tissue, creating different scattering or reflection properties that are visible on the image as contrasting features or regions.

[0012] The system 10 has several drawbacks. Because each receiver 19 is associated with one transmitter 18, if the mast is far from the object to be imaged, the signal level captured by any one receiver 19 may be low or overwhelmed by noise. As a result, the width of the entrance 14 and the width of the exit 15 in the conventional design of the system 10 are both small, e.g., between 24 and 29 inches wide, and may not comfortably accommodate larger individuals or individuals with mobility aid devices such as wheelchairs. Additionally, the use of a ceiling to mount the mast to a rigid "tuning fork" central mounting structure may be an obstacle for tall individuals or individuals wearing hats or other head gear. Furthermore, the geometry of the system 10 requires the individual to rotate 90° to face the side direction 28 before scanning can begin, which requires instruction to and compliance by the individual and may delay scanning until the individual is correctly positioned. The system 10 also does not employ other detection or scanning modalities such as metal detection or shoe scanning. The system 10 may not properly image parts of an individual at the end of the mast, such as a hat or shoe.

[0013] The systems and methods described herein overcome some or all of the shortcomings of system 10 by using imaging masts that move in unison in a mirror image fashion through the individual along a common horizontal direction (front to back or back to front (i.e., the masts move in unison in a common horizontal direction from entrance to exit or exit to entrance)) without rotating 90° as the individual enters the system. By transmitting and receiving electromagnetic radiation during a mirror image arc or linear motion through the individual, the masts can use a multistatic reconstruction methodology to image the individual posed in a forward facing direction 117. FIG. 2 illustrates a top view of a mmWave system 100 for scanning an individual posed in a forward facing direction according to some embodiments described herein. The system 100 includes a room 111 having an entrance 114 and an exit 115. The system 100 includes one or more imaging masts 120a, 120b. In some embodiments, the system 100 includes a non-invasive walk-through metal detector 130. In some embodiments, the system 100 includes a floor imaging unit 140. The system 100 can include indicator markings 113, such as footprint markings, near a center point 116 of the system 100.

[0014] Operation of the system 100 produces a greater amount of quality data for image reconstruction compared to the conventional system 10. Due to the geometric configuration of the imaging masts 120a, 120b, and the increased number of transmit and receive elements active at one time, the system 100 can receive sufficient data to reconstruct an image even with increased spacing between the masts 120 and the individual being imaged. Thus, the system 100 can have entry and exit widths that accommodate wheelchairs or walkers, or other assistive devices. The increased entry and exit widths of the system 100 not only accommodate a greater variety of individuals, but also provide beneficial advantages over conventional systems with smaller entry and exit widths. In some embodiments, the system 100 also utilizes transmit and receive antenna elements that compensate for circular polarization to improve data quality and allow for sufficient data acquisition to reconstruct an image even with greater spacing between the masts and the individual being imaged.

[0015] According to the teachings herein, an individual enters the room 111 through the entrance 114 and stands in a forward facing orientation 117 at or near the indicator marking 113. The individual may stand with their arms at their sides. The individual pauses momentarily while the imaging masts 120a, 120b move in unison on their respective scan paths through the individual in a common horizontal direction from the entrance to the exit or vice versa. The paths followed by the imaging masts 120a, 120b may be straight paths in a common horizontal direction from the entrance to the exit or vice versa, or may be arcuate paths in a common horizontal direction from the entrance to the exit or vice versa. The imaging masts 120a, 120b are oriented in a mirror image arrangement. A transmitter 128 on the imaging mast transmits electromagnetic radiation, such as millimeter wave radiation, toward the individual. The radiation reflects or scatters from the individual and is received by a receiver 129 located on the imaging masts 120a, 120b. The receiver 129 transmits the received signal data to the computing device 150, which applies a reconstruction algorithm to the received signal data to reconstruct an image of at least a portion of the individual or object associated with the individual. Additionally, in some embodiments, a transmitter in the floor imaging unit 140 can transmit electromagnetic radiation upward from the floor toward the individual. Electromagnetic radiation from below is reflected or scattered from the individual and received by a receiver in the floor imaging unit 140. The geometry and mirror motion of the imaging mast, combined with advances in signal processing described in more detail herein below, allows for improved image quality and an improved user experience in which a user can continue to face forward with hands at their sides or on their hips throughout the imaging process, rather than facing sideways 118 and placing their hands on their head. In some embodiments, the system 100 can scan an individual and provide an image to the user in less than 6 seconds. In some embodiments, the system 100 can enable the scanning and imaging of at least 600 individuals per hour.The ability of an individual to hold their hands at their sides during imaging is due in part to the positioning and movement of the masts 120a, 120b, which allows for mirror image imaging between the masts 120a, 120b. By comparison, the masts in conventional systems are consistently 180° out of phase, which all but precludes the use of reflected energy between the masts.

[0016] As used herein, the reference number 120 is used to refer to any imaging mast, but a particular imaging mast within a particular system embodiment is referred to using the reference number 120 followed by a letter (e.g., first imaging mast 120a). The imaging masts 120a, 120b sweep the transmission and reception of radiation along respective scan paths 125 in a mirror image configuration on either side (e.g., first and second sides) of an individual facing forward at a center point 116. For example, the first imaging mast 120a can sweep the transmission and reception of radiation on a first scan path 125 on the left side of the center point 116, while the second imaging mast 120b can sweep the emission and transmission of electromagnetic radiation on a second scan path 125 on the right side of the center point 116 that is a mirror image of the first scan path 125 across a central horizontal axis 127. In some embodiments, the imaging masts 120a, 120b physically traverse a scan path 125, similar to the embodiment of FIG. 2. The physical scan path can be essentially arcuate or linear. In some embodiments, as previously described, the first imaging mast 120a and the second imaging mast 120b move in unison in a common horizontal direction relative to a central horizontal axis 127. For example, the central horizontal axis 127 can be coincident with the forward direction 117. The central horizontal axis 127 can pass through the center point 116. In some embodiments, the central horizontal axis 127 can be defined by the aspect of the object to be imaged, for example, by an anatomical mid-plane or an anatomical mid-sagittal plane of an individual. The first imaging mast 120a passes through a first side of the object to be imaged, and the second imaging mast 120b passes through a second side of the object to be imaged. For a scan path having curvature, the direction of rotation of the first mast 120a along its scan path 125 (e.g., counterclockwise from the perspective of the center point 116) is opposite to the direction of movement of the second imaging mast 120b along its arc-shaped scan path 125 (e.g., clockwise from the perspective of the center point 116).This opposing rotation results in the imaging masts 120 on different sides of the center point 116 moving in a common horizontal direction, unlike conventional systems where the rotation of the masts is in the same direction (ie, clockwise or counterclockwise) from the perspective of the center point 116.

[0017] In yet another embodiment, the imaging masts 120a, 120b can move in unison in a common horizontal direction relative to the entrance 114 and the exit 115 of the room 111, i.e., both masts 120a, 120b can move on a scan path 125 having a start position close to the entrance 114 and an end position close to the exit 115, or on a scan path 125 having a start position close to the exit 115 and an end position close to the entrance 114. In some embodiments, the common directionality of the scan paths is reversed for each scan operation. In other words, the imaging masts 120a, 120b can proceed in a direction from the entrance to the exit for one scan and in a reverse direction from the exit to the entrance for a subsequent scan. In some embodiments, the scan paths 125 of the masts 120a, 120b are configured such that the masts 120a, 120b start at a first separation distance from each other at the start position of the scan path. As the masts 120a, 120b move along the scan path, they move away from each other to reach a second separation distance from each other that is greater than the first separation distance. When the masts 120a, 120b reach the end of the scan path, the masts 120a, 120b are separated by a third separation distance that is less than the second separation distance. In some embodiments, the sweep of the first imaging mast 120a on the first scan path 125 and the sweep of the second imaging mast 120b on the second scan path 125 occur simultaneously. In some embodiments, the timing of the sweep of the first imaging mast 120a on the first scan path 125 and the timing of the sweep of the second imaging mast 120b on the second scan path 125 occur staggered or offset. In some embodiments, the scan path 125 of the masts 120a, 120b is configured such that the masts 120a, 120b begin a first separation distance from each other at the start of the scan path and then maintain the separation distance as they pass the individual, i.e., in some embodiments, the masts 120a, 120b maintain parallelism from the start to the end position.

[0018] The use of mirror image or counter rotating (i.e., one mast moves clockwise while the other mast moves counterclockwise simultaneously) scan paths 125 in the embodiments of the present disclosure allows scattered or reflected electromagnetic radiation generated from a transmitter 128 on the first mast 120a to be received by a receiver 129 located on the second mast 120b or the first mast 120a or both. This results in a higher diversity of measured scattering angles in the imaging data set, creating more imaging data for each emission event. The higher amount of imaging data, and the higher diversity in the imaging data, allows for the generation of better quality images when data is acquired using a scan path 125 that has a shorter linear distance or covers fewer angles than conventional devices, as described in more detail below. The higher amount of imaging data, and the higher diversity in the imaging data, also allows for the generation of better quality images using data acquired from an imaging mast 120 that is farther away from the individual than conventional systems 1. As a result, a shorter scan path results in faster scanning, thus improving throughput and allowing the use of larger rooms with larger entrances 114 and exits 115. In some embodiments, the width of the entrance 114 or the width of the exit 115 can be at least 32 inches (approximately 81.3 centimeters) or can have a value within a range of 32 inches (81.3 cm) to 48 inches (121.9 cm). In some embodiments, the width of the entrance 114 or the width of the exit 115 can comply with minimum or maximum width requirements imposed by ordinances, regulations, or statutes, such as the Americans with Disabilities Act (ADA).

[0019] The imaging mast 120, in some embodiments, can be connected to one or more mounts, frameworks, or linkages that are connected to the ceiling or floor of the room 111. Motors can be operatively coupled to the one or more mounts to enable movement of the mast 120 along the scan path 125. In some embodiments, the motors are connected to the mounts via gearboxes. In an alternative configuration, the masts 120a, 120b can be mounted on rails or slides. In this arrangement, the masts 120a, 120b can translate along the rails or slides to traverse the scan path 125. In embodiments in which the masts 120 are mounted on rails or slides, the room 111 can be designed without a ceiling, since no overhead mounting structure is used to mount and move the masts 120. As a result, naturally tall individuals or individuals who wear headgear may be more comfortable when using a ceiling-free system, since they do not need to bend down or remove their headgear.

[0020] As shown in the top view of FIG. 2, the mast 120 can be mounted in a vertical configuration in which the transmitters 128 and receivers 129 of the mast 120 are stacked on top of each other in a direction parallel to the height of the individual (i.e., from the floor to the ceiling). In other embodiments, the post 120 can be mounted in a horizontal configuration in which the transmitters 128 and receivers 129 are stacked on top of each other in a direction parallel to the floor (e.g., approximately parallel to the forward direction 117). In this arrangement, the scan path 125 is oriented vertically (i.e., moving from the top downwards towards the floor of the room 111 or moving upwards from the floor of the room 111). The mast 120 in the horizontal configuration can slide along rails or slides to move along the scan path.

[0021] Each imaging mast 120 includes one or more electromagnetic radiation transmitters 128 and one or more electromagnetic radiation receivers 129. In some embodiments, the transmitters 128 and receivers 129 are organized into self-contained modules that can be easily connected or stacked and are removable or replaceable. Each mast 120 can include 1 to 200 transmitters and 1 to 200 receivers. In some embodiments, each mast 120 includes 9 modules, each module including 8 transmitters 128 and 12 receivers 129. A mast 120 suitable for use in the systems of the present disclosure is shown in process detail with respect to FIG. 6. The systems and methods described herein can employ active imaging (i.e., both emitting and receiving electromagnetic radiation), passive imaging (i.e., receiving naturally generated or ambient electromagnetic radiation such as blackbody radiation), or both active and passive imaging. In some embodiments, the transmitters 128, receivers 129, or both the transmitters 128 and receivers 129 can be circularly polarized compensated.

[0022] In some embodiments of the present disclosure, the electromagnetic radiation is millimeter wave radiation. In some embodiments, millimeter wave radiation can be used alone or in combination with one or more other forms of electromagnetic radiation, such as terahertz radiation, infrared radiation, or other radiation. In some embodiments, the frequency or wavelength of the electromagnetic radiation can be selected based on the penetration depth of the electromagnetic radiation at that frequency or wavelength through layers of common organic materials. Millimeter wave generally refers to radiation having a frequency of about 20 to 300 GHz (gigahertz). In one embodiment, the receiver is sensitive to frequencies within a relatively narrow band of the millimeter wave spectrum. In some embodiments, the receiver is sensitive to one or more frequency bands somewhere within the range of about 20 GHz to 300 GHz. In one embodiment, the receiver operates in a band spanning some or all of the frequency spectrum between 90 GHz and 140 GHz. For example, a receiver may be tuned to receive 94 GHz millimeter waves with an instantaneous bandwidth of about 6 GHz, or any receiver may include multiple radiometric receivers each operating in discrete bands of about 6 GHz, each receiver centered on three to five discrete center frequencies between 20 and 300 GHz. For example, bands encompassing one or more of the following frequencies may be used: 35 GHz, 94 GHz, 140 GHz, and 220 GHz.

[0023] As shown in Figures 3 and 4, the transmission and reception of electromagnetic radiation can occur within the same mast or across different masts (sometimes referred to herein as "cross-mast"). Figure 3 illustrates an imaging modality in which radiation 305 transmitted from a transmitter 128 of a first mast 120a is scattered or reflected back (310) to a receiver on the first mast 120a. Some embodiments of the present system and method include transmission from more than one transmitter at a time. In embodiments in which more than one transmitter 128 is located on each imaging mast 120, the transmitters 128 on the same mast 120 may transmit radiation sequentially or simultaneously, or in selected groups, such as the top 50% of transmitters and the bottom 50% of transmitters, or alternating groups of transmitters by vertical position on the mast. In some embodiments, all transmitters 128 on the same mast 120 can transmit simultaneously. In some embodiments, all transmitters 128 on both masts 120 can transmit radiation simultaneously. Radiation emitted from multiple transmitters 128 can be detected by multiple receivers 129. The number of transmitters 128 and receivers 129 involved in a time step (e.g., a time point when the mast moves) of an imaging operation is factorial. In some embodiments, a coding scheme can be used so that radiation received at a particular receiver 129 can be associated with a respective transmitter 128 based on the coding scheme. For example, each transmitter 128 can transmit electromagnetic radiation having a signature, such as a frequency signature, an amplitude signature, or a phase signature, or electromagnetic radiation modulated in a unique manner. In some embodiments, the computing device 150 can control the number of transmitters 128 and the number of receivers 129 used in an imaging operation based on a desired range of sizes of objects to be imaged or a desired throughput.The computing device 150 may receive parameters related to a desired range of object sizes or a desired throughput from a user (e.g., via a graphical user interface) or based on a set of rules, which may include the location of the system and factors such as time of day or detected slowdowns. In some environments, it may be desirable for smaller objects to be imaged (e.g., detection of objects such as memory cards at an exit to a secure facility) and more transmitters 128 and receivers 129 may be used to improve resolution. In some environments, high throughput is desirable and fewer transmitters 128 and receivers 129 may be used to reduce computational overhead.

[0024] In various embodiments, the computing system 150 can apply a monostatic reconstruction algorithm, a multistatic reconstruction algorithm, or both algorithms to data received by one or more receivers 129. To use a monostatic reconstruction algorithm, the computing system receives imaging data from a receiver 129 associated with an actively transmitting transmitter 128. The monostatic reconstruction algorithm utilizes a significant computational simplification using a point source approximation that approximates the transmitting and receiving locations as a single point. In some embodiments of the present disclosure, the computing device can receive imaging data from a remote (i.e., non-collocated or non-associated) receiver 129 that is too far away to allow the use of a point source approximation. In some embodiments, the computing device 150 receives imaging data from more than one receiver 129 or from all receivers 129 on the same imaging mast 120a during the emission of radiation by a single transmitter 128. The transmit and receive sequence continues for each transmitter on the imaging mast 120a. The computing device 150 then controls the imaging mast 120a to advance radiation azimuthally or linearly along the scan path 125, and the transmit / receive sequence begins again. Azimuthally or linearly advancing can refer to a physical translation of the imaging mast 120, as in the embodiments of Figs. 2 and 5, or tilting or pivoting of the imaging mast 120 to aim at a different location on the reflector 170, as in the embodiment of Fig. 7. The use of imaging data from receivers that are far enough away to be approximated as being located at the same "point" as the transmitter allows the use of multistatic reconstruction techniques. For example, the use of multiple receivers that receive while a single transmitter transmits forms a multistatic system. A multistatic system can be used to form a set of bistatic images. The multiple bistatic images can be combined coherently or incoherently to form a three-dimensional reconstruction of the imaged scene.

[0025] 4 illustrates an imaging modality in which radiation 305 transmitted from a first mast 120a is scattered or reflected 315 to a receiver on a second mast 120b. A computing device can receive imaging data from one, multiple, or all receivers 129 on the second mast 120b that correspond to the emission of radiation from a transmitter on the first imaging mast 120a.

[0026] In some embodiments, the transmitter on the first mast 120a transmits radiation in a first time step. The reflected or scattered radiation is received by receivers on both the first mast 120a and the second mast 120b. In a subsequent time step (i.e. after the masts 120a, 120b have moved a specified azimuth or linear distance), the transmitter on the first mast 120a stops transmitting and the transmitter on the second mast 120b starts transmitting radiation. The reflected or scattered radiation emanating from the second mast 120b is received by receivers on both the first mast 120a and the second mast 120b. The geometry of the system 100 allows any given receiver 129 to receive scattered or reflected radiation emanating from several transmitters 128 both on the same mast and on cross masts. In some embodiments, the number of possible combinations of active transmitters and active receivers in a given time step is factorial.

[0027] The mirror image scan path 125 of the present disclosure allows for the use of cross-mast detection, as shown in Figure 4. In a conventional system, such as the system 10 of Figure 1, two imaging masts 12 orbit around the individual at a fixed distance and in the same rotational direction. The location of the individual at the center point 16 means that the individual blocks most of the electromagnetic radiation transmitted by the transmitter 18 in the mast 12. The blocking of the electromagnetic radiation by the individual means that little or no reflected or scattered signal can reach the imaging mast 12 located on the opposite side.

[0028] In some embodiments, the computing device 150 can obtain information regarding the relative location of the transmitter 128 and each receiver 129 at a given time during an imaging sweep across the scan path 125. For example, this information can be obtained by the computing device 150 from an encoder attached to each imaging mast 120 that identifies the absolute position of the imaging mast 120. As another example, the computing device 150 can control the movement of the imaging mast 120 and estimate the position or location based on a calibration curve that relates the value (e.g., voltage) of an output signal from the computing device 150 to the position of the imaging mast 120. In some embodiments, the computing device 150 can filter imaging data obtained when the first imaging mast 120a and the second imaging mast 120b are substantially opposite each other. Filtering can separate radiation scattered from an individual from directly received radiation that travels directly from a transmitter on one imaging mast 120a to a receiver on another imaging mast 120b when the transmitter on one imaging mast 120a and the receiver on another imaging mast 120b are in diametrically opposed positions.

[0029] In some embodiments, the scan path 125 of the mast 120 can be shorter (e.g., cover fewer angles or a shorter linear distance) than the scan path of the receiver in a conventional system. Specifically, the additional data throughput provided by the systems and methods described herein can enable reconstruction of a high quality image even with data acquired over a smaller set of angles (or distances) than the set of angles (or distances) required in a conventional system. In some embodiments, the length of the scan path can be reduced by a value in the range of 10% to 50% compared to the length of the conventional scan path 25. In some embodiments, the length of the scan path 125 in the present disclosure can be reduced by 33% compared to the length of the conventional scan path 25. In some embodiments, the length of the scan path 125 can be in the range of between 40 inches (about 100 cm) and 60 inches (about 150 cm).

[0030] The system 100 may employ automatic initiation in some embodiments. The imaging masts 120 may be used as "radar" units to detect the distance between the individual and the central point 116. In some embodiments, the transmitters 128 from one or both imaging masts 120a, 120b may begin transmitting radiation while the individual enters the room 111 and walks toward the central point 116. The computing device 150 may then receive imaging data from the receivers 129 on one or both imaging masts 120a, 120b before the individual stops at the central point 116. In some embodiments, the transmitters 128 from one or both imaging masts 120a, 120b may begin transmitting radiation when the individual enters the room 111 and stands at the central point 116. The computing device 150 may then receive imaging data from the receivers 129 on one or both imaging masts 120a, 120b before the individual stops at the central point 116. The computing device 150 can process the imaging data to determine the position of the individual relative to the imaging mast 120 or the central point 116. In some embodiments, the computing device 150 can identify that the individual has stopped at the central point 116 and can automatically initiate a scan or prompt an operator of the system to initiate a scan. In some embodiments, the computing device 150 can adjust the xy position of the floor imaging unit 140 based on the detected location of the individual within the room 111.

[0031] Returning to FIG. 2 , the non-invasive walk-through metal detector 130 can detect the presence of metal or metal objects on the body of an individual as the individual walks through the metal detector 130. In some embodiments, the non-invasive walk-through metal detector 130 has the shape of an arch or doorway. The non-invasive walk-through metal detector 130 can surround the entrance 114 of the room 111 such that the individual must pass through the metal detector 130 to enter the room 111. In conventional security floor plans and layouts, such as security screening areas at airports, millimeter wave scanning and metal detection are often provided as parallel alternatives where an individual passes through one device or the other. Such parallel setups reduce the overall detection efficiency since only one detection modality is used for each individual. To achieve both metal detection and millimeter wave scanning, an individual must pass through one device, return to the entrance, and pass through a second device, which reduces the throughput of the system. By combining the non-invasive walk-through metal detector 130 and electromagnetic radiation scanning (e.g., millimeter wave scanning) in a single system 200, both detection modalities can be used on an individual in a single pass, thereby increasing throughput and overall detection efficiency. Data from the metal detector 130 can also be combined with imaging data from the imaging mast 120 to improve the quality of the final image. Additional details regarding the non-invasive walk-through metal detector 130 are provided below with respect to FIG. 9.

[0032] The room 111 may include materials that are absorptive or transparent to the electromagnetic radiation (eg, millimeter wave or radar signals) emitted by the transmitters 128, 148.

[0033] The floor imaging unit 140 is disposed on or under the floor of the room 111 supporting the individual. The floor imaging unit 140 includes one or more electromagnetic radiation transmitters 148 and one or more receivers 149. The transmitters 148 transmit electromagnetic radiation upward toward the feet of the individual. Radiation scattered or reflected from the individual is received by the receivers 149. In some embodiments, one or more of the transmitters in the floor imaging unit 140 are mounted on an xy gantry that moves one or more of the transmitters 148 in an xy direction under the feet of the individual. In some embodiments, one or more of the transmitters and one or more receivers in the floor imaging unit 140 are mounted on an xy gantry that moves one or more of the transmitters 148 and one or more receivers 149 in an xy direction under the feet of the individual. The receivers 149 transmit the imaging data to a computing device 150, which can apply a reconstruction algorithm to the imaging data to reconstruct an image of at least a portion of the shoes of the individual. In some embodiments, the computing device 150 can apply a reconstruction algorithm to both the imaging data from the floor imaging unit 140 and the imaging data from the one or more imaging masts 120 to create an image of a portion of the individual. In some embodiments, the receivers in the masts 120a, 120b are active during operation of the floor imaging unit 140. In some embodiments, the transmitters in the masts 120a, 120b are active during operation of the floor imaging unit 140. In some embodiments, the transmitters 128 in the masts 120a, 120b and the receivers 129 in the masts 120a, 120b are active during operation of the floor imaging unit 140. In this manner, imaging from the masts and floor imaging units can be combined or otherwise used to image and evaluate the shoes of the individual.

[0034] In conventional security floor plans or layouts, individuals often remove their footwear while passing through the system 10 so that the footwear can be individually scanned for contraband using a complementary luggage / baggage / parcel scanning system, for example, a system using x-ray imaging. Removing and re-wearing the footwear by the individual results in significant delays, a negative user experience, and additional strain and delays on the complementary luggage / baggage / parcel scanning system that must scan the footwear. The floor imaging unit 140 of the present disclosure improves scanning throughput and user satisfaction by performing footwear scans while the footwear is still being worn by the individual. In some embodiments, the floor imaging unit 140 can perform footwear scans simultaneously with performing other scans or imaging of the individual, such as during a scanning sweep of the imaging mast 120. In some embodiments, the transmitter of the floor imaging unit 140 transmits millimeter wave radiation. In some embodiments, the transmitter of the floor imaging unit 140 transmits infrared radiation.

[0035] 5 illustrates an embodiment of the system 100 in which the imaging masts 120a, 120b undergo movement on a linear scan path 125 rather than an arcuate scan path 125. As previously mentioned, the imaging masts 120a, 120b can be mounted on slides or rails that allow the masts to translate along the scan path 125 during data acquisition.

[0036] 6A-6C show steps in a motion sequence of an embodiment of the system 100 in which the imaging masts 120a, 120b undergo motion on a linear scan path 125 while simultaneously pivoting about a pivot axis 119 perpendicular to the direction of the scan path 125 (e.g., perpendicular to the forward direction 117). Pivoting the imaging masts 120a, 120b during motion along the scan path 125 can ensure that the transmitter 128 is aimed toward the center point 116. In this way, the amount of radiation reaching the individual (and scattered or reflected by the individual) is increased. In some embodiments, the pivot axis 119 can pass through the imaging masts 120. For example, each mast 120 can be attached to pivots at the top and bottom of the mast. In other embodiments, the pivot axis 119 can pass outside the imaging masts 120. For example, the masts 120 can be connected to pivots at the rear panel of the mast. In some embodiments, beam streaming techniques may be used in lieu of mechanical devices that may be used to rotate, pivot, or tilt the masts 120a, 120b as they move in unison in a common horizontal direction. In some embodiments, individual receivers, or transmitters, or both, are beam steered. In some embodiments, groups of receivers or transmitters (e.g., modules), or both, are beam steered. In some embodiments, all receivers, or all transmitters, or both, are beam steered. Beam steering advantageously focuses energy on an individual in a dynamically configured, optimized manner when one wishes to tune the system to maximize certain attributes (such as items popping out on the first pass in a multiple pass protocol) or to focus on specific areas where a person is trying to hide things, e.g., under a hat, in the groin, etc.

[0037] 7 shows an embodiment of the system 100 in which the transmitters 128 of the imaging masts 120a, 120b transmit radiation towards a reflector 170. The reflector 170 redirects the transmitted radiation towards a central point 116. Radiation emitted or scattered from an individual reaches the reflector 170 and is redirected towards a receiver 129 on the imaging masts 120a, 120b. In this arrangement, the imaging masts 120a, 120b can rotate in position to transmit and receive radiation along the entire extent of the reflector 170. Thus, the scan path 125 is virtual, since the transmitted radiation is directed towards the central point 116 from a set of points along the surface of the reflector 170, and the returning radiation is received from a set of points along the surface of the reflector 170.

[0038] In some embodiments, the imaging masts 120a, 120b do not physically rotate. Rather, electronic beam steering is used to change the directionality of transmission and reception relative to the reflector 170. In some embodiments of the system 100, the imaging masts 120a, 120b remain stationary and the reflector 170 rotates, translates, or pivots to direct the transmission or reception of electronic radiation to different areas within the room 111. In some embodiments, the reflector 170 can be part of a reflecting system for an adjustable optical path between the imaging masts 120a, 120b and the individual to be scanned.

[0039] 8A and 8B show perspective and front views of an imaging mast 120 for use in some embodiments of the systems and methods of the present disclosure. As previously described, the imaging mast 120 can be configured with stacked, adjacent, or non-adjacent modules 121, each including one or more transmitters 128 and one or more receivers 129. The modules 121 can be removable or replaceable. In the imaging mast 120 shown in FIGS. 8A and 8B, each imaging mast includes nine modules 121. However, it should be understood that the imaging mast 120 can include any number of modules 121 or can be configured using separate transmitters, receivers, and other mechanical or electronic components assembled as modules in various embodiments. Each module 121 shown in FIGS. 8A and 8B includes eight transmitters 128 and twelve receivers 129. However, it should be understood that each module 121, or indeed each imaging mast, may include any suitable number of transmitters 128 and receivers 129 as desired to achieve a given final image resolution.

[0040] FIG. 9 is a schematic diagram illustrating a front view of a non-invasive walk-through metal detector 130 according to some embodiments described herein. The non-invasive walk-through metal detector 130 can detect the presence of metal or a metal object carried on the body of an individual as the individual passes through the non-invasive walk-through metal detector. In some embodiments, the non-invasive walk-through metal detector can locate the presence of a detected metal object in one or more spatial detection zones 135 within a volume of space through which the individual passes. For example, the metal detector 130 can use multiple pulsed induction coils to generate a localized magnetic field that is disturbed or affected by the presence of a metal object. By ascertaining the effect of each coil on the magnetic field, the metal object can be located in a particular spatial detection zone 135. The volume of space measured by the non-invasive walk-through metal detector can include the entrance 114 of the room 111 or the exit 115 of the room 111 in various embodiments.

[0041] The computing device 150 can receive data from the non-invasive walk-through metal detector that identifies a spatial detection zone in which a metal object was detected. The computing device 150 can use this information during execution of a reconstruction algorithm to generate an image of a portion of the individual. For example, if the non-invasive walk-through metal detector 130 detects an object in a spatial detection zone that corresponds to a location at the individual's right hip (e.g., a particular distance from the floor on the individual's right hand side), the computing device 150 can use a finer reconstruction mesh during reconstruction of a spatial volume that includes the individual using imaging data from the imaging mast 120. Alternatively, the computing device 150 can control the imaging mast 120 to sweep more slowly a portion of the scan path that corresponds to a spatial volume that includes the individual's right hip. In some embodiments, the computing device 150 can control the imaging mast 120 to perform multiple transmit / receive cycles using a transmitter 128 that most fully illuminates the individual's right hip (e.g., a transmitter 128 located at approximately waist height along the length of the imaging mast 120b). In some embodiments, the non-invasive walk-through metal detector 130 can be selectively disabled to allow individuals with contraindicating medical conditions to pass through the metal detector 130. In some embodiments, the non-invasive walk-through metal detector 130 can be selectively used as a pre-screening device to allow an operator to instruct individuals to step down or exit the line rather than enter the line.

[0042] 10 is a block diagram of a computing device 150 suitable for use in embodiments of the present disclosure. The computing device 150 may be, but is not limited to, a smartphone, a laptop, a tablet, a desktop computer, a server, or a network appliance. The computing device 150 includes one or more non-transitory computer-readable media for storing one or more computer-executable instructions or software for implementing various embodiments taught herein. The non-transitory computer-readable media may include, but is not limited to, one or more types of hardware memory (e.g., memory 156), non-transitory tangible media (e.g., storage device 426, one or more magnetic storage disks, one or more optical disks, one or more flash drives, one or more solid-state disks), etc. For example, the memory 156 included within the computing device 150 may store computer readable and computer executable instructions 460 or software for carrying out the operations of the computing device 150 (e.g., instructions for receiving data from the receiver 129 of the imaging mast 120, the receiver 149 of the floor imaging unit 140, or the non-invasive walk-through metal detector 130, instructions for performing an image reconstruction method using a monostatic or multistatic reconstruction algorithm 462, etc.). The computing device 150 also includes a configurable and / or programmable processor 155 and associated cores 404, and optionally one or more additional configurable and / or programmable processors 402′ and associated cores 404′ (e.g., in the case of a computer system having multiple processors / cores) for executing the computer readable and computer executable instructions or software stored within the memory 156, as well as other programs for carrying out embodiments of the present disclosure. The processor 155 and the processor 402′ may each be a single-core processor or a multi-core (404 and 404′) processor.Either or both of the processor 155 and the processor 402 ′ may be configured to execute one or more of the instructions described in connection with the computing device 150 .

[0043] Virtualization may be applied in computing device 150 so that infrastructure and resources within computing device 150 may be dynamically shared. Virtual machines 412 may be provided to handle processes running on multiple processors so that the processes appear to be using only one computing resource rather than multiple computing resources. Multiple virtual machines may also be used with one processor.

[0044] The memory 156 may include computer system memory or random access memory, such as DRAM, SRAM, EDO RAM, etc. The memory 156 may also include other types of memory, or combinations thereof.

[0045] A user may interact with computing device 150 through a visual display device 414, such as a computer monitor, which may display one or more graphical user interfaces 416. A user may interact with computing device 150 using a multi-point touch interface 420 or a pointing device 418.

[0046] The computing device 150 may also include one or more computer storage devices 426, such as a hard drive, CD-ROM, or other computer readable medium for storing data and computer readable instructions 460 and / or software implementing exemplary embodiments (e.g., applications) of the present disclosure. For example, the exemplary storage device 426 may include instructions 460 or software routines that enable data exchange with one or more of the imaging masts 120a, 120b, the floor imaging unit 140, and the non-invasive walk-through metal detector 130. The storage device 426 may also include reconstruction algorithms 462 that can be applied to the imaging data and / or other data to reconstruct an image of the scanned object.

[0047] The computing device 150 may include a communication interface 154 configured to interface with one or more networks, e.g., a local area network (LAN), a wide area network (WAN), or the Internet, via one or more network devices 424, through a variety of connections including, but not limited to, a standard telephone line, a LAN or WAN link (e.g., 802.11, T1, T3, 56 kb, X.25), a broadband connection (e.g., ISDN, Frame Relay, ATM), a wireless connection, a controller area network (CAN), or some combination of any or all of the above. In an exemplary embodiment, the computing device 150 may include one or more antennas 422 that facilitate wireless communication (e.g., via a network interface) between the computing device 150 and a network and / or between the computing device 150 and components of a system, such as the imaging mast 120, the floor imager unit 140, or the metal detector 130. Communications interface 154 may include an embedded network adapter, a network interface card, a PCMCIA network card, a card bus network adapter, a wireless network adapter, a USB network adapter, a modem, or any other device suitable for interfacing a computing device to any type of network over which the computing device can communicate and for performing the operations described herein.

[0048] Computing device 150 may execute an operating system 410, such as versions of the Microsoft® Windows® operating system, different releases of Unix® and Linux® operating systems, versions of MacOS® for Macintosh computers, embedded operating systems, real-time operating systems, open source operating systems, proprietary operating systems, or other operating systems capable of executing on computing device 150 and performing the operations described herein. In an exemplary embodiment, operating system 410 may execute in a native mode or an emulated mode. In an exemplary embodiment, operating system 410 may execute on one or more cloud machine instances.

[0049] 11 illustrates a network environment 500 including a computing device 150 and other elements of the systems described herein suitable for use in an exemplary embodiment. The network environment 500 can include one or more databases 152, one or more imaging masts 120, 120a, 120b, one or more non-invasive walk-through metal receivers 130, one or more floor imaging units 140, and one or more computing devices 150, which can communicate with each other via a communications network 505.

[0050] The computing device 150 may host one or more applications (e.g., instructions 460 or software, reconstruction algorithms 462, or graphical user interface 416) configured to interact with one or more components of the system 100 and / or to facilitate access to the contents of the database 152, which communicate with or control the imaging mast 120, the transmitter 128, the receiver 129, the metal receiver 130, the floor imaging unit 140, the floor transmitter 148, or the floor receiver 149, and any mechanical, mechanical, or electronic systems associated with these system aspects. The database 152 may store information or data, including the instructions 460 or software, the reconstruction algorithms 462, or imaging data, as described above. Information from the database 152 may be retrieved by the computing device 150 over the network 505 during imaging or scanning operations. The database 152 may be located in one or more geographically distributed locations remote from some or all of the system components (e.g., imaging mast 120, floor imaging unit 140, metal detector 130) and / or computing device 150. Alternatively, the database 152 may be located in the same geographic location as the computing device 150 and / or in the same geographic location as the system components. The computing device 150 may be geographically remote from the room 111 or other system components (e.g., mast 120, metal detector 130, floor imaging unit 140, etc.). For example, the computing device 150 and operator may be located in a secure room isolated from where scanning of individuals occurs to mitigate privacy concerns. The computing device 150 may also be located completely off-site at a remote facility.

[0051] In an example embodiment, one or more portions of the communications network 505 may be an ad-hoc network, a mesh network, an intranet, an extranet, a virtual private network (VPN), a local area network (LAN), a wireless LAN (WLAN), a wide area network (WAN), a wireless wide area network (WWAN), a metropolitan area network (MAN), a portion of the Internet, a portion of the public switched telephone network (PSTN), a cellular network, a wireless network, a Wi-Fi network, a WiMAX network, an Internet of Things (IoT) network established using Bluetooth® or any other protocol, any other type of network, or a combination of two or more such networks.

[0052] FIG. 12 illustrates a method 1000 for screening an individual by detecting a concealed object carried by the individual using a system embodiment of the present disclosure. The method 1000 generates an image of the object, which may include all or a portion of the individual himself, an object carried by the individual, or both. The method 1000 is applicable for use in any of the embodiments described herein, such as the embodiments of FIG. 2, FIG. 5, or FIG. 7. The method 1000 includes a step of transmitting electromagnetic radiation from one of a plurality of transmitters 128 of the first imaging mast 120a or the second imaging mast 120b (step 1002). The method 1000 also includes a step of receiving, at the computing device 150, imaging data indicative of reception of electromagnetic radiation scattered or reflected from the object by a plurality of first receivers 129 of the first imaging mast 120a and a plurality of second receivers 129 of the second imaging mast 120b (step 1004). The method includes moving the first imaging mast 120a and the second imaging mast 120b in unison in a common horizontal direction relative to the central horizontal axis 127 (Step 1006).

[0053] Steps 1002, 1004, and 1006 can be repeated until the imaging masts reach the end of their scan paths 125 to collect enough imaging data to allow for three-dimensional image reconstruction. In some embodiments, the emission from the multiple transmitters can be performed sequentially. For example, the computing device 150 can cause each of a first plurality of transmitters on the first imaging mast 120a to transmit radiation in a specified sequence (e.g., end-to-end, center-to-end, or another alternating sequence of the masts). The computing device 150 can then cause each of a second plurality of transmitters on the second imaging mast 120b to transmit radiation in a specified sequence. Once each transmitter in the system has transmitted radiation, the sequence can be restarted from the beginning as the two masts continue to move in unison.

[0054] When the imaging masts 120 reach the end of their scan paths, data acquisition is complete and an image can be reconstructed. Method 1000 includes reconstructing an image of the object (step 1008) by applying a reconstruction algorithm (e.g., a multistatic reconstruction algorithm) of computing device 150 to the imaging data.

[0055] In some embodiments, step 1006 can be replaced with a different step, and the system can utilize a non-translating imaging mast and reflector as in Figure 7. For example, the swapping step can involve physical rotation of mast 120 and / or transmitter 128, or the use of electronic beamforming methods to move the location of the main radiation lobe of transmitter 128 to a different point on reflector 170, as described above.

[0056] The following analysis of the method 1000 with respect to a particular embodiment should not be construed as limiting. The method 1000 can be performed using a system 100 such as that of FIG. 2 utilizing an imaging mast 120 similar to that shown in FIG. 8A-8B. If all nine modules 121 of the imaging mast 120 are used in performing the method 1000, the first imaging mast 120a generates nine times as much imaging data as would be generated using a conventional method (i.e., single module transmission and reception, which allows the use of a point source approximation as described above). At the same time, the module 121 of the second imaging mast 120b also generates nine additional sets of imaging data for a total of 18 times improvement in the imaging data of a single point along the scan path. The method 1000 alternates between emitting between the transmitter 128 of the first mast 120a at the first location and the transmitter 128 of the second mast 120 at the second location, whereas the conventional method activates transmitters from both masts at each location. As a result, the data throughput of method 1000 is approximately 9 times that of the conventional method. Overall, method 1000 collects approximately 6 times more image data compared to conventional systems and methods. The increased amount of image data collected per sweep or scan allows for the use of shorter scan paths. The increased amount of data is due to an embodiment in which all transmitting and receiving elements in mast 120, 120b transmit and receive at once, compared to conventional systems in which transmitters and receivers are turned on and off sequentially. In an embodiment that allows an individual to walk around system 100 without stopping, method 1000 collects approximately 62 times more imaging data compared to conventional systems and methods.

[0057] In describing the exemplary embodiments, specific terminology is used for clarity. Additionally, in some instances where a particular exemplary embodiment includes multiple system elements, device components, or method steps, those elements, components, or steps may be replaced with a single element, component, or step. Similarly, a single element, component, or step may be replaced with multiple elements, components, or steps that serve the same purpose. Furthermore, while the exemplary embodiments have been illustrated and described with reference to specific embodiments thereof, those skilled in the art will recognize that various substitutions and changes in form and details may be made without departing from the scope of the present disclosure. Additionally, other aspects, features, and advantages are within the scope of the present disclosure.

[0058] The exemplary flow charts are provided herein for illustrative purposes and are non-limiting examples of methods. Those skilled in the art will recognize that the exemplary methods may include more or fewer steps than those shown in the exemplary flow charts, and that the steps in the exemplary flow charts may be performed in a different order than that shown in the exemplary flow charts. [Explanation of symbols]

[0059] 100 mmWave System, System 111 rooms 113 Indicative markings 114 Entrance 115 Exit 116 Center point 117 forward facing direction, forward direction 118 Lateral 119 Pivot axis 120 Mast 120a mast, first imaging mast, first mast 120b mast, second imaging mast, second mast 121 Modules 125 Arc-shaped scan path, first scan path, second scan path, mirror image scan path, arc-shaped scan path, linear scan path 127 Center horizontal axis 128 Transmitter, Electromagnetic Radiation Transmitter 129 Receiver, Electromagnetic Radiation Receiver 130 Non-invasive walk-through metal detector, metal detector, non-invasive walk-through metal receiver, metal receiver 135 Spatial Detection Zone 140 Floor imaging unit, floor imager unit 148 Transmitter, Electromagnetic Radiation Transmitter, Floor Transmitter 149 Receiver, Floor Receiver 150 Computing devices, computing systems 152 Database 154 Communication Interface 155 Configurable and / or programmable processors, processors 156 Memory 170 Reflector 200 Systems 305 Radiation 402' configurable and / or programmable processor, processor 404 Core 404' Core 410 Operating Systems 412 Virtual Machines 414 Visual Display Devices 416 Graphical User Interface 418 Pointing Device 420 Multi-point Touch Interface 422 Antenna 424 Network Devices 426 Storage devices, computer storage devices 460 Computer-Readable and Computer-Executable Instructions, Computer-Readable Instructions, Instructions 462 Monostatic or multistatic reconstruction algorithms, reconstruction algorithms 500 Network environment 505 Communication Network

Claims

1. a first imaging mast including a first plurality of electromagnetic radiation transmitters and a first plurality of electromagnetic radiation receivers, the first imaging mast configured to move past a first side of an object disposed along a central horizontal axis to image at least a first portion of the object; a second imaging mast including a second plurality of electromagnetic radiation transmitters and a second plurality of electromagnetic radiation receivers, the second imaging mast configured to move past a second side of the object to image at least a second portion of the object, the first imaging mast and the second imaging mast configured to move in unison in a common horizontal direction relative to the central horizontal axis; A computing device including a processing unit, the computing device comprising: instructions for receiving imaging data from the first imaging mast, the second imaging mast, or both imaging masts, the imaging data representing electron radiation reflected or scattered by the object as the first imaging mast and the second imaging mast move through the object; instructions for applying a reconstruction algorithm to the imaging data to generate an image of at least a portion of the object; A computing device configured to execute A scanning system comprising:

2. The scanning system of claim 1 , wherein the movement of the first imaging mast on a first scan path and the movement of the second imaging mast on a second scan path occur simultaneously.

3. 13. The scanning system of claim 1, further comprising a floor imaging unit including one or more transmitters of electromagnetic radiation and one or more receivers of electromagnetic radiation, the one or more transmitters of the floor imaging unit configured to transmit radiation upward from below a floor configured to support the object.

4. The scanning system of claim 3, wherein the computing device is further configured to execute instructions to receive imaging data from the one or more receivers of the floor imaging unit, and the instructions to apply the reconstruction algorithm further include applying the reconstruction algorithm to imaging data from the first imaging mast, the second imaging mast, and the floor imaging unit to generate the image of at least the portion of the object.

5. 13. The scanning system of claim 1, further comprising a non-invasive walk-through metal detector configured to detect the presence of metal or metal objects within one or more spatial detection zones within a volume of space through which the object passes.

6. The scanning system of claim 5 , wherein the volume of space includes an entrance to the detection system.

7. the computing device is further configured to execute instructions to receive data from the non-invasive walk-through metal detector identifying a spatial detection zone in which the presence of metal or a metal object is detected; and wherein the instructions for applying the reconstruction algorithm further include applying the reconstruction algorithm to the imaging data from the first imaging mast and the second imaging mast and to the data from the non-invasive walk-through metal detector.

6. The scanning system of claim 5.

8. 2. The scanning system of claim 1, wherein at least one of the plurality of second receivers on the second imaging mast is configured to receive radiation transmitted by at least one of the plurality of first transmitters of the first imaging mast.

9. The scanning system of claim 1 , wherein the reconstruction algorithm is a multistatic reconstruction algorithm.

10. The scanning system of claim 1 , wherein the computing device is configured to receive imaging data before the first imaging mast and the second imaging mast begin to move.

11. The scanning system of claim 1 , wherein the first imaging mast moves on a first arcuate scan path and the second imaging mast moves on a second arcuate scan path.

12. 10. The scanning system of claim 1, wherein the first imaging mast moves on a first linear scan path and the second imaging mast moves on a second linear scan path.

13. 13. The scanning system of claim 12, wherein the first imaging mast is configured to pivot about an axis perpendicular to the first linear scan path during movement of the first imaging mast on the first linear scan path such that the one or more receivers of the first imaging mast point toward a center point during the movement.

14. The scanning system of claim 1 , wherein the first portion of the object at least partially overlaps the second portion of the object.

15. The scanning system of claim 1 , wherein the scanning system is a millimeter wave scanning system.

16. 1. A method of scanning an object, comprising: transmitting electron radiation from one of a plurality of transmitters of the first imaging mast or the second imaging mast; receiving, at a computing device, imaging data indicative of reception of electromagnetic radiation scattered or reflected from the object by a plurality of first receivers of the first imaging mast and a plurality of second receivers of the second imaging mast; moving the first imaging mast and the second imaging mast in unison in a common horizontal direction relative to a central horizontal axis; reconstructing an image of the object by applying a multistatic reconstruction algorithm of the computing device to the imaging data; A method comprising:

17. The method of claim 16 , wherein the movement of the first imaging mast on a first scan path and the movement of the second imaging mast on a second scan path occur simultaneously.

18. receiving imaging data from one or more receivers of the floor imaging unit; and reconstructing the image of the object further comprises applying a reconstruction algorithm to the imaging data from the floor imaging unit. The method of claim 16.

19. receiving data from the non-invasive walk-through metal detector identifying a spatial detection zone in which the presence of metal or a metal object is detected; and wherein reconstructing the image of the object further comprises applying a reconstruction algorithm to the data from the non-invasive walk-through metal detector. The method of claim 16.

20. 17. The method of claim 16, wherein at least one of the plurality of second receivers on the second imaging mast is configured to receive radiation transmitted by at least one of the plurality of transmitters of the first imaging mast.

Images