Patent Description:
The embodiments described herein relate generally to CT imaging systems, and more particularly, to contactless data communication for CT imaging systems.

In some computed tomography (CT) imaging systems, an x-ray source projects a fan-shaped beam that is collimated to lie within an X-Y plane of a Cartesian coordinate system and generally referred to as an "imaging plane". The x-ray beam passes through an object being imaged. The beam, after being attenuated by the object, impinges upon an array of radiation detectors. The intensity of the attenuated radiation beam received at the detector array is dependent upon the attenuation of the x-ray beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the beam intensity at each detector location. The intensity measurements from all the detectors are acquired separately to produce a transmission profile and reconstruct an image of the object.

At least some known CT systems include a gantry that rotates within a stationary housing. To control operation of the CT system, data is communicated between the rotating gantry and stationary housing. For example, imaging data acquired by detectors on the gantry may be communicated to a computing device for processing (e.g., image reconstruction). To communicate between the gantry and housing, at least some known CT systems use an optical communication system (e.g., a laser transmitter and an optical receiver). Further, at least some known CT systems use capacitive coupling between a transmitter on one of the gantry and the housing and a receiver on the other of the gantry and the housing. However, these known communication systems may be unidirectional, and may also require relatively high tolerances for proper operation.

<CIT> discloses: a CT imaging system for imaging an object, said CT imaging system comprising: a stationary component; a rotating component configured to rotate with respect to said stationary component; a first conductive line coupled to said rotating component; and a second conductive line coupled to said stationary component, wherein said first conductive line defines a discontinuity; wherein said first and second conductive lines are positioned proximate one another such that inductive crosstalk between said first and second conductive lines provides a contactless communication channel for communicating data between said stationary component and said rotating component; the CT imaging system further comprising: a first bracket coupled to said stationary component at a first location and configured to act as an antenna to facilitate the inductive crosstalk; wherein the contactless communication channel provides bi-directional communication between said stationary component and said rotating component.

<CIT> discloses first and second conductive elements, e.g. electrically conductive wires on rotor and stator for bi-directional communication. The document further shows that stator and rotor each comprise a conductive component made up of e.g. two wires.

<CIT> discloses a CT imaging system with stationary and rotating components, data transmitter on the rotating gantry and receiver on the stationary gantry. The document further discloses that the distance between rotating segments is small to avoid discontinuities between the segments and mentions that in some embodiments, the sections of the circular stripline antennas are phased to reduce or eliminate phase discontinuities in coupled data signals.

<CIT> also discloses a CT imaging system for imaging an object with a stationary and a rotary component, the stator or rotor comprising a first data communication component and the rotor or stator comprising a second data communication component. At least one of the first and second data communication components extending over nearly a complete ring, over nearly the entire surface of the stator or rotor, therefore implying the presence of a discontinuity. The system allows inductive crosstalk between first and second components for bi-directional data transmission. The first (and similarly the second) component is made up of a number of circuit board assemblies and a support structure holding the components together.

<CIT> shows on/off control of receivers coupled to the stationary component with passing/ not passing of the first conductive component made up of two transmitting antennae.

In one aspect, a CT imaging system for imaging an object is provided according to claim <NUM>.

In another aspect, a method for contactless data communication in a CT imaging system is provided according to claim <NUM>.

The systems and methods described herein provide a contactless communication system for a CT imaging system. At least one first conductive line is coupled to a stationary component of the CT imaging system. At least one second conductive line is coupled to a rotating component of the CT imaging system. Inductive crosstalk between the first and second conductive lines provides a contactless communication channel that may be used to communicate data bi-directionally between the stationary component and the rotating component.

Referring now to <FIG> and <FIG>, a computed tomography (CT) imaging system <NUM> is shown. CT imaging system <NUM> is shown having a gantry <NUM>, which is representative of a CT scanner, a control system <NUM>, and a motorized conveyor belt <NUM> for positioning an object <NUM>, such as a piece of luggage, in a gantry opening <NUM> defined through gantry <NUM>. Gantry <NUM> includes an x-ray source <NUM> that projects a fan beam of x-rays <NUM> toward a detector array <NUM> on the opposite side of gantry <NUM>. Detector array <NUM> is formed by detector elements <NUM>, which are radiation detectors that each produce a signal having a magnitude that represents and is dependent on the intensity of the attenuated x-ray beam after it has passed through object <NUM> being imaged. During a helical scan that acquires x-ray projection data, gantry <NUM> along with the x-ray source <NUM> and detector array <NUM> rotate within an x-y plane and around object <NUM> about a center of rotation, while object <NUM> is moved through gantry <NUM> in a z-direction <NUM> perpendicular to the x-y plane of rotation. In the exemplary embodiment, detector array <NUM> includes a plurality of detector rings each having a plurality of detector elements <NUM>, the detector rings having an angular configuration corresponding to x-ray source <NUM>.

Gantry <NUM> and x-ray source <NUM> are controlled by control system <NUM>, which includes a gantry controller <NUM>, an x-ray controller <NUM>, a data acquisition system (DAS) <NUM>, an image reconstructor <NUM>, a conveyor controller <NUM>, a computer <NUM>, a mass storage system <NUM>, an operator console <NUM>, and a display device <NUM>. Gantry controller <NUM> controls the rotational speed and position of gantry <NUM>, while x-ray controller <NUM> provides power and timing signals to x-ray source <NUM>, and data acquisition system <NUM> acquires analog data from detector elements <NUM> and converts the data to digital form for subsequent processing. Image reconstructor <NUM> receives the digitized x-ray data from data acquisition system <NUM> and performs an image reconstruction process that involves filtering the projection data using a helical reconstruction algorithm.

Computer <NUM> is in communication with the gantry controller <NUM>, x-ray controller <NUM>, and conveyor controller <NUM> whereby control signals are sent from computer <NUM> to controllers <NUM>, <NUM>, <NUM> and information is received from controllers <NUM>, <NUM>, <NUM> by computer <NUM>. Computer <NUM> also provides commands and operational parameters to data acquisition system <NUM> and receives reconstructed image data from image reconstructor <NUM>. The reconstructed image data is stored by computer <NUM> in mass storage system <NUM> for subsequent retrieval. An operator interfaces with computer <NUM> through operator console <NUM>, which may include, for example, a keyboard and a graphical pointing device, and receives output, such as, for example, a reconstructed image, control settings, and other information, on display device <NUM>.

Communication between the various system elements of <FIG> is depicted by arrowhead lines, which illustrate a means for either signal communication or mechanical operation, depending on the system element involved. Communication amongst and between the various system elements may be obtained through a hardwired or a wireless arrangement. For example, inductive crosstalk between two conductive lines may be used as a communication channel, as described herein. Computer <NUM> may be a standalone computer or a network computer and may include instructions in a variety of computer languages for use on a variety of computer platforms and under a variety of operating systems. Other examples of computer <NUM> include a system having a microprocessor, microcontroller, or other equivalent processing device capable of executing commands of computer-readable data or program for executing a control algorithm. In order to perform the prescribed functions and desired processing, as well as the computations therefor (e.g., the execution of filtered back projection, Fourier analysis algorithm(s), the control processes prescribed herein, and the like), computer <NUM> may include, but not be limited to, a processor(s), memory, storage, register(s), timing, interrupt(s), communication interfaces, and input/output signal interfaces, as well as combinations including at least one of the foregoing. For example, computer <NUM> may include input signal filtering to enable accurate sampling and conversion or acquisitions of such signals from communications interfaces. As described above, exemplary embodiments can be implemented through computer-implemented processes and apparatuses for practicing those processes.

<FIG> is a block diagram of a computing device <NUM> that may be used to reconstruct an image of object <NUM>, as described herein. Computing device <NUM> may be implemented as part of control system <NUM> or may be a separate computing device in communication with CT imaging system <NUM> or another imaging system. Computing device <NUM> includes at least one memory device <NUM> and a processor <NUM> that is coupled to memory device <NUM> for executing instructions. In some embodiments, executable instructions are stored in memory device <NUM>. In the exemplary embodiment, computing device <NUM> performs one or more operations described herein by programming processor <NUM>. For example, processor <NUM> may be programmed by encoding an operation as one or more executable instructions and by providing the executable instructions in memory device <NUM>.

Processor <NUM> may include one or more processing units (e.g., in a multi-core configuration). Further, processor <NUM> may be implemented using one or more heterogeneous processor systems in which a main processor is present with secondary processors on a single chip. In another illustrative example, processor <NUM> may be a symmetric multi-processor system containing multiple processors of the same type. Further, processor <NUM> may be implemented using any suitable programmable circuit including one or more systems and microcontrollers, microprocessors, reduced instruction set circuits (RISC), application specific integrated circuits (ASIC), programmable logic circuits, field programmable gate arrays (FPGA), graphics processing units (GPU), and any other circuit capable of executing the functions described herein.

In the exemplary embodiment, memory device <NUM> is one or more devices that enable information such as executable instructions and/or other data to be stored and retrieved. Memory device <NUM> may include one or more computer-readable media, such as, without limitation, dynamic random access memory (DRAM), static random access memory (SRAM), a solid state disk, and/or a hard disk. Memory device <NUM> may be configured to store, without limitation, application source code, application object code, source code portions of interest, object code portions of interest, configuration data, execution events and/or any other type of data. Further, reference templates may be stored on memory device <NUM>.

In the exemplary embodiment, computing device <NUM> includes a presentation interface <NUM> that is coupled to processor <NUM>. Presentation interface <NUM> presents information to a user <NUM>. For example, presentation interface <NUM> may include a display adapter (not shown) that may be coupled to a display device, such as a cathode ray tube (CRT), a liquid crystal display (LCD), an organic LED (OLED) display, and/or an "electronic ink" display. In some embodiments, presentation interface <NUM> includes one or more display devices.

In the exemplary embodiment, computing device <NUM> includes a user input interface <NUM>. User input interface <NUM> is coupled to processor <NUM> and receives input from user <NUM>. User input interface <NUM> may include, for example, a keyboard, a pointing device, a mouse, a stylus, a touch sensitive panel (e.g., a touch pad or a touch screen), a gyroscope, an accelerometer, a position detector, and/or an audio user input interface. A single component, such as a touch screen, may function as both a display device of presentation interface <NUM> and user input interface <NUM>.

Computing device <NUM>, in the exemplary embodiment, includes a communication interface <NUM> coupled to processor <NUM>. Communication interface <NUM> communicates with one or more remote devices (e.g., in some embodiments, CT imaging system <NUM>). To communicate with remote devices, communication interface <NUM> may include, for example, a wired network adapter, a wireless network adapter, and/or a mobile telecommunications adapter.

To control operation of CT imaging system <NUM>, data is communicated between one or more static components (e.g., a stationary housing for gantry <NUM>) and one or more rotating components (e.g., gantry <NUM> itself). As used herein, a 'rotating component' refers to a component that rotates relative to a 'static component'. In the systems and methods described herein, inductive crosstalk is utilized to communicate data between static components and rotating components. This enables contactless communications between rotating and static components, as described herein.

In the exemplary embodiment, communication utilizing inductive crosstalk is accomplished using at least two conductors, or lines. At least one first line is located on a rotating component of CT imaging system <NUM>, and at least one second line is located on a static component of CT imaging system <NUM>. Notably, first and second lines do not physically contact one another, but data is communicated between first and second lines using inductive crosstalk.

<FIG> is a schematic diagram illustrating electromagnetic interactions between a first conductive line <NUM> and a second conductive line <NUM>. For example, as a first current travels along first conductive line <NUM>, a first magnetic field <NUM> is generated around first conductive line <NUM>. First magnetic field <NUM> in turn induces a second magnetic field <NUM> around second conductive line <NUM>. As shown in <FIG>, first magnetic field <NUM> is in a direction opposite second magnetic field <NUM> (e.g., if first magnetic field <NUM> is clockwise, second magnetic field <NUM> is counterclockwise). Second magnetic field <NUM> causes a second current to flow through second conductive line <NUM>.

In this example, because the first current in first conductive line <NUM> causes generation of the second current in second conductive line <NUM>, first conductive line <NUM> may be referred to as the 'aggressor' line, and second conductive line <NUM> may be referred to as the 'victim' line. Of course, those of skill in the art will appreciate that an initial current in second conductive line <NUM> will generate a subsequent current in first conductive line <NUM>, in which case second conductive line <NUM> is the aggressor line and first conductive line <NUM> is the victim line.

Because first and second conductive lines <NUM> and <NUM> do not physically contact one other (either directly or through other conductive components), first and second conductive lines <NUM> and <NUM> do not have a common ground. As such, there is no capacitive crosstalk between first and second conductive lines <NUM> and <NUM>. Rather, there is only inductive crosstalk between first and second conductive lines <NUM> and <NUM>.

There are two components of inductive crosstalk between first and second conductive lines <NUM> and <NUM>: near end crosstalk and far end crosstalk. The near end crosstalk between first and second conductive lines <NUM> and <NUM> can be represented as: <MAT> where CM is the mutual capacitance between first and second conductive lines <NUM> and <NUM>, CL is the capacitance per unit length of first and second conductive lines <NUM> and <NUM>, LM is the mutual inductance between first and second conductive lines <NUM> and <NUM>, and LL is the inductance per unit length of first and second conductive lines <NUM> and <NUM>.

The far end crosstalk between first and second conductive lines <NUM> and <NUM> can be represented as: <MAT> where 'length' is the coupling length of first and second conductive lines <NUM> and <NUM>, trise is the risetime of the signal on the aggressor conductive line (i.e., first conductive line <NUM>), CM is the mutual capacitance between first and second conductive lines <NUM> and <NUM>, CL is the capacitance per unit length of first and second conductive lines <NUM> and <NUM>, LM is the mutual inductance between first and second conductive lines <NUM> and <NUM>, and LL is the inductance per unit length of first and second conductive lines <NUM> and <NUM>.

As can be seen from Equation <NUM>, the near end crosstalk does not depend on trise. Further, the near end crosstalk is always a positive value. In contrast, as can be seen from Equation <NUM>, the far end crosstalk does depend on trise. Further, if the ratios of capacitances and inductances are equal, the far end crosstalk cancels out. This occurs if all of the magnetic field lines are contained within a homogenous dielectric material.

The total crosstalk is the superposition of the near end cross talk and the far end crosstalk. Further, the near end crosstalk results in a flat magnitude variation on the communication channel, and the far end crosstalk contributes to distortion in the flatness of the communication channel.

Turning now to <FIG>, one example embodiment of CT imaging system <NUM> for implementing inductive crosstalk is illustrated. More particularly, <FIG> is a front view of a portion of CT imaging system <NUM>, <FIG> is a perspective view of a portion of CT imaging system <NUM>, and <FIG> is another perspective view of a portion of CT imaging system <NUM>. As shown in <FIG>, CT imaging system <NUM> includes a stationary component <NUM> and a rotating component <NUM>. In the illustrated embodiment, stationary component <NUM> is embodied as one or more brackets <NUM>, <NUM>. In other embodiments, stationary component <NUM> may include, for example, a housing or stationary frame of CT imaging system <NUM>. In the illustrated embodiment, rotating component <NUM> includes, for example, gantry <NUM> of CT imaging system <NUM> or a slip ring of CT imaging system <NUM>.

As shown in <FIG>, a first conductive line <NUM> is coupled to rotating component <NUM>. First conductive line <NUM>, embodied as two parallel wires <NUM>, <NUM>, extends circumferentially about gantry <NUM>. Moreover, each of wires <NUM>, <NUM> includes a respective seam <NUM>, at which a first end and a second end of each wire <NUM>, <NUM> meet come together to close the loop of the wire <NUM>, <NUM>. Seam <NUM> represents a discontinuity in first conductive line <NUM>, and, accordingly, seam <NUM> is preferably as small as possible. The size of seam <NUM> may be limited by the need to ensure completion of the loop of each wire <NUM>, <NUM>. It should be understood that the size of seam <NUM> is exaggerated in <FIG> for clarity.

As shown in <FIG>, a cut-away view of bracket <NUM>, a second conductive line <NUM> is coupled to stationary component <NUM>, specifically to bracket <NUM>. Second conductive line <NUM> is embodied as a wire <NUM> substantially the same as wire <NUM>, <NUM> of first conductive line <NUM>, except that wire <NUM> forms a much smaller loop (i.e., a loop positioned on a bottom surface <NUM> of bracket <NUM>) and wire <NUM> is stationary.

First and second conductive lines <NUM> and <NUM> are positioned proximate one another, such that inductive crosstalk occurs between first and second conductive lines <NUM> and <NUM>, as described above. Communication between first and second conductive lines <NUM> and <NUM> is bidirectional. Specifically, to communicate data from stationary component <NUM> to rotating component <NUM>, second conductive line <NUM> functions as the aggressor and second conductive line <NUM> functions as the victim. To communicate data from rotating component <NUM> to stationary component <NUM>, first conductive line <NUM> functions as the aggressor and first conductive line <NUM> functions as the victim.

In the exemplary embodiment, orthogonal frequency-division multiplexing (OFDM) is used as the physical layer to communicate over the communication channel between first and second conductive lines <NUM> and <NUM> provided by inductive crosstalk. Further, in the exemplary embodiment, communication is accomplished by shifting the WiFi frequency standard (which typically operates in a <NUM> to <NUM> Gigahertz (GHz) frequency band) to below the <NUM> to <NUM> band. Specifically, OFDM is used to modulate the frequency into the RF band, which results in relatively lower tolerances and allows for bidirectional communication. The error vector magnitude (EVM) of such a configuration may be kept relatively low (e.g., below <NUM>%).

As explained above, the inductive crosstalk between first and second conductive lines <NUM> and <NUM> has a near end component and a far end component. The far end component of the crosstalk may be reduced by tuning the system and adjusting the mechanical design of the system. Moreover, the discontinuity at seam <NUM> may be reduced as rotating component <NUM> is rotated at high speeds. In addition, CT imaging system <NUM> includes two brackets <NUM>, <NUM>. Each bracket <NUM>, <NUM> is configured to act as an antenna for CT imaging system <NUM> to facilitate inductive crosstalk as described herein. In the example embodiment, brackets <NUM>, <NUM> are positioned opposite one another across CT imaging system <NUM>, or about <NUM>° from one another about the circumference of a frame or housing of CT imaging system <NUM>. Brackets <NUM>, <NUM> may be otherwise spaced from one another about the circumference the housing of CT imaging system <NUM>.

When the discontinuity at seam <NUM> is near and/or directly under one bracket <NUM>, acting as the antenna, bracket <NUM> begins to experience two discontinuous waveforms, causing signal interference. Accordingly, CT imaging system <NUM> is configured to switch to bracket <NUM> as the antenna substantially immediately before bracket <NUM> encounters seam <NUM>, to avoid the discontinuity of the seam <NUM> disrupting communications. Specifically, in one embodiment, each bracket <NUM>, <NUM> includes an optical sensor <NUM> at a leading end thereof (i.e., the end of bracket <NUM>, <NUM> that will first encounter seam <NUM>). When optical sensor <NUM> detects seam <NUM>, optical sensor <NUM> transmits a signal (e.g., to computer <NUM>, shown in <FIG>) that causes a switch, such that the opposite bracket <NUM>, <NUM> acts as the antenna (until that opposite bracket encounters seam <NUM>, which triggers another switch).

The embodiments described herein provide a contactless communication system for a CT imaging system. A second conductive line is coupled to a stationary component of the CT imaging system. A first conductive line is coupled to a rotating component of the CT imaging system. Inductive crosstalk between the first and second conductive lines provides a contactless communication channel that may be used to communicate data bi-directionally between the stationary component and the rotating component. Notably, the embodiments described herein are not limited to use with CT imaging systems, but - as an example not forming part of the claimed invention-may be used for contactless bi-directional data communication in other implementations.

The systems and methods described herein may be used to detect contraband. As used herein, the term "contraband" refers to illegal substances, explosives, narcotics, weapons, special nuclear materials, dirty bombs, nuclear threat materials, a threat object, and/or any other material that a person is not allowed to possess in a restricted area, such as an airport. Contraband may be hidden within a subject (e.g., in a body cavity of a subject) and/or on a subject (e.g., under the clothing of a subject). Contraband may also include objects that can be carried in exempt or licensed quantities intended to be used outside of safe operational practices, such as the construction of dispersive radiation devices.

A computer, such as those described herein, includes at least one processor or processing unit and a system memory. The computer typically has at least some form of computer readable media. By way of example and not limitation, computer readable media include computer storage media and communication media. Computer storage media include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules, or other data. Communication media typically embody computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism and include any information delivery media. Those skilled in the art are familiar with the modulated data signal, which has one or more of its characteristics set or changed in such a manner as to encode information in the signal. Combinations of any of the above are also included within the scope of computer readable media.

Exemplary embodiments of methods and systems are described above in detail. The methods and systems are not limited to the specific embodiments described herein, but rather, components of systems and/or steps of the methods may be used independently and separately from other components and/or steps described herein. Accordingly, the exemplary embodiment can be implemented and used in connection with many other applications not specifically described herein.

Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.

Claim 1:
A CT imaging system for imaging an object, said CT imaging system comprising:
a stationary component;
a rotating component configured to rotate with respect to said stationary component;
a first conductive line coupled to said rotating component; and
a second conductive line coupled to said stationary component; wherein said first conductive line defines a discontinuity;
wherein said first and second conductive lines are positioned proximate one another such that inductive crosstalk between said first and second conductive lines provides a contactless communication channel for communicating data between said stationary component and said rotating component,
wherein the contactless communication channel provides bi-directional communication between said stationary component and said rotating component; characterized in the CT imaging system further comprising:
a first bracket coupled to said stationary component at a first location and configured to act as an antenna to facilitate the inductive crosstalk; and
a second bracket coupled to said stationary component at a second location spaced from the first location about a circumference defined by said stationary component and configured to act as an antenna to facilitate the inductive crosstalk;
and wherein the system is configured to switch from the first bracket acting as an antenna to the second bracket acting as the antenna to avoid the discontinuity disrupting communications due to rotation of the rotating component.