Combined x-ray system and pilot tone system

Abstract

An X-ray system (100, 700) configured for acquiring medical imaging data (134) from an object (102) at least partially within an imaging zone (105) is disclosed. The X-ray system comprises a memory (128) storing machine executable instructions (130). The X-ray system further comprises a processor (122) configured for controlling the X-ray system. The X-ray system further comprises a pilot tone system (106), wherein the pilot tone system comprises a radio frequency system (108) comprising a plurality of transmit channels (110) and a plurality of receive channels (112). The plurality of transmit channels is configured for transmitting a plurality of pilot tone signals (136) via a plurality of transmit coils (114). The plurality of receive channels is configured for receiving pilot tone data (138) via a plurality of receive coils (116). Execution of the machine executable instructions causes the processor to transmit (202) the plurality of pilot tone signals by controlling the plurality of transmit channels, to acquire (204) the pilot tone data by controlling the plurality of receive channels, and to determine (206) a motion state (140, 700, 700', 702, 702') of the object using the pilot tone data.

Description

TECHNICAL FIELD

[0001] The present invention relates to X-ray imaging, in particular to the use of a pilot tone to detect subject motion. BACKGROUND

[0002] In X-ray imaging techniques such as X-ray computed tomography, fluoroscopy and X-ray imaging, medical imaging data is acquired from a subject and used to reconstruct a medical image. This enables a physician or other health care professional to accurately image the internal anatomy of a subject. A drawback of these techniques is that the subject can move during the acquisition of the medical imaging data, which can result in the addition of artefacts in the medical image or X-ray.

[0003] European patent application EP 3413076 relates to an MRI system with a pilot tone generator for generating a cardiac motion signal. This known pilot tone transmitter is formed as a separate single radio frequency source generating a single pilot tone signal. SUMMARY

[0004] The present invention provides an X-ray system, a computer program product and a method, and embodiments are presented.

[0005] Embodiments of the present invention can provide an improved method for determining a motion state of a subject for an X-ray system. Embodiments can provide this by using a pilot tone system. In a pilot tone system, a pilot tone signal (radio frequency signal) is transmitted using a transmitting coil and then received using at least one receiving coil. The pilot tone data is a signal in the receiving coil caused by the transmission of the pilot tone signal. When the subject moves, the RF coupling between the transmitting coil and the receiving coil changes. The change in RF coupling causes a change in the pilot tone data, which can be used to determine the motion state of the subject.

[0006] In one aspect, the application provides an X-ray system configured for acquiring medical imaging data from an object at least partially within an imaging zone. The X-ray system comprises a memory storing machine executable instructions. The X-ray system further comprises a processor for controlling the X-ray system. The X-ray system further comprises a pilot tone system. The pilot tone system comprises a radio frequency system comprising at least one transmit channel and at least one receive channel. The at least one transmit channel is configured for transmitting at least one pilot tone signal via at least one transmit coil. The at least one receive channel is configured for receiving pilot tone data via at least one receive coil. The pilot tone system is based on transmission of pilot tone signals as electromagnetic signals, e.g. in a radio frequency range of e.g. 40-400 MHz. The pilot tone signals are transmitted in a continuous wave (cw) mode, and the pilot tone data is due to an impedance response to the transmitted pilot tone signals. The response is represented by a change in amplitude and phase of the pilot tone data relative to the amplitude and phase of the transmitted pilot tone signals. That is, the pilot tone data represents a frequency domain response to the pilot tone signals, and spectral resolution information is carried by the pilot tone data.

[0007] Execution of the machine executable instructions further causes the processor to transmit at least one pilot tone signal by controlling the at least one transmit channel. Execution of the machine executable instructions further causes the processor to acquire pilot tone data by controlling the at least one receive channel to receive pilot tone data. Execution of the machine executable instructions further causes the processor to determine a motion state of the object using the pilot tone data. This embodiment can be beneficial as it can provide an efficient means of monitoring a motion state of an object during an X-ray examination.

[0008] In different examples, the X-ray system can take different forms. In one example, the X-ray system is a computed tomography system or CT system. In another example, the X-ray system is a fluoroscope.

[0009] In another embodiment, the X-ray system is an X-ray imaging system configured for acquiring two-dimensional X-rays. All previously mentioned X-ray systems can benefit from the use of a pilot tone system.

[0010] In another embodiment, the at least one transmit channel is a plurality of transmit channels. The at least one transmit coil has a plurality of transmit coils. Transmitting the at least one pilot tone signal by controlling the at least one transmit channel comprises transmitting a multi-channel pilot tone signal by controlling at least a portion of the plurality of transmit channels. Acquiring the pilot tone data by controlling the at least one receive channel to receive the pilot tone data comprises acquiring multi-channel pilot tone data by controlling at least a portion of the plurality of receive channels to receive the pilot tone data.

[0011] Determining the motion state of the object using the pilot tone data includes determining the motion state of the object using the multi-channel pilot tone data. This embodiment can be beneficial because multiple transmit channels and multiple receive channels are used. This enables a greater degree of information about the motion of the object.

[0012] The radio frequency system is configured to encode each of the multi-channel pilot tone signals using any of the following: frequency encoding, phase encoding, complex modulation, CDMA encoding, and combinations thereof. This embodiment can be beneficial because it can provide an efficient means of distinguishing the source of the pilot tone signals when multiple signals are received. This can improve the ability to determine the motion state of the object.

[0013] In another embodiment, the at least one receive channel is a plurality of receive channels. The at least one receive coil is a plurality of receive coils. This embodiment can be beneficial because multiple receive coils can be placed in different locations and then the placement of the object relative to the pilot tone system is less sensitive.

[0014] In another embodiment, the motion state is any of the following: object motion position, motion vector, object motion classification, respiration state, cardiac motion state, a translation vector describing at least a portion of the object, a rotation describing at least a portion of the object, and combinations thereof.

[0015] In another embodiment, execution of the machine executable instructions further causes the processor to determine the motion state using a recurrent neural network configured to receive the pilot tone data and the at least one pilot tone signal and then to output the motion state. This embodiment can be beneficial because it can be trained to recognize complex patterns.

[0016] In another embodiment, execution of the machine executable instructions further causes the processor to determine the motion state by detecting a distance between each of the at least one receive coil and the object. As the object gets closer to a particular receive coil, the coupling can increase. This can provide a model that can be used to efficiently but simply determine the position of the object.

[0017] In another embodiment, execution of the machine executable instructions further causes the processor to determine the motion state by detecting using digital filtering. Various periodic motions, such as breathing or a heartbeat, will produce pilot tones with characteristic frequencies. Digital filtering enables such motions, like the heart or breathing, to be accurately and easily detected.

[0018] In another embodiment, execution of the machine executable instructions further causes the processor to determine the motion state using principal component analysis. This embodiment can be beneficial because it is possible to form a principal component analysis model using a large number of previously acquired pilot tone signals and pilot tone data.

[0019] In another embodiment, execution of the machine executable instructions further causes the processor to control the X-ray system to acquire the medical imaging data during acquisition of the pilot tone data. This embodiment can be beneficial because the pilot tone data can then be used, for example, to control the functioning and operation of the X-ray system and / or later to reconstruct X-ray or medical images.

[0020] In another embodiment, execution of the machine executable instructions further causes the processor to reconstruct a medical image using the medical imaging data. Execution of the machine executable instructions further causes the processor to correct the reconstruction of the medical image using the motion state of the object. This embodiment can be particularly beneficial in case the X-ray system is a tomographic system such as a CT system. Knowledge of the position of the object can help to take the motion of the object into account during reconstruction of the medical image.

[0021] In another embodiment, execution of the machine executable instructions further causes the processor to gate the acquisition of the medical imaging data using the motion state of the object. For example, if the motion state is a breathing phase or a heart phase, gating of the object can be useful to produce a resulting image of the heart or breathing phase of the object.

[0022] In another embodiment, execution of the machine executable instructions further causes the processor to modify the acquisition of the medical imaging data using the motion state of the object. For example, in tomographic medical imaging techniques such as CT, the determination of the motion state can be used to change the type and position of the coordinate system in which the acquired medical imaging data is located. This can be useful, for example, to compensate for the motion of the object during acquisition of the medical imaging data.

[0023] In another embodiment, the pilot tone system further comprises at least one transmit coil and / or at least one receive coil.

[0024] In another embodiment, the X-ray system further comprises an object support for supporting at least a portion of the object in the imaging zone. At least a portion of the at least one transmit coil and at least a portion of the at least one receive coil are integrated into the object support. This can be beneficial because it can provide an efficient means of incorporating a pilot tone system into an X-ray system.

[0025] The processor for controlling the pilot tone system can also be integrated into the object support. For example, the pilot tone system can be fully contained within the object support. This can for example be achieved by using the object support for the addition of the pilot tone system to the X-ray system. The object support can also be used for different imaging techniques, such as magnetic resonance imaging. A single object support can be moved to different imaging systems and different types of imaging systems.

[0026] In another embodiment, the X-ray system is an X-ray computed tomography system. This can be beneficial, because the exact position of the object can be beneficial when controlling the X-ray computed tomography system and / or during reconstruction to improve the quality of the medical images or X-rays from the X-ray system.

[0027] In another aspect, the application provides a computer program product comprising machine executable instructions for execution by a processor configured for controlling an X-ray system. The X-ray system is configured for acquiring medical imaging data from an object being at least partially within an imaging zone. The X-ray system comprises a pilot tone system. The pilot tone system comprises a radio frequency system comprising at least one transmit channel and at least one receive channel. The at least one transmit channel is configured for transmitting at least one pilot tone signal via at least one transmit coil. The at least one receive channel is configured for receiving pilot tone data via at least one receive coil.

[0028] Execution of the machine executable instructions further causes the processor to transmit at least one pilot tone signal by controlling the at least one transmit channel. Execution of the machine executable instructions further causes the processor to acquire pilot tone data by controlling the at least one receive channel to receive pilot tone data. Execution of the machine executable instructions further causes the processor to determine a motion state of the object using the pilot tone data.

[0029] In another aspect, the application provides a method of operating an X-ray system configured for acquiring medical imaging data from an object being at least partially within an imaging zone. The X-ray system comprises a pilot tone system. The pilot tone system comprises a radio frequency system comprising at least one transmit channel and at least one receive channel. The at least one transmit channel is configured for transmitting at least one pilot tone signal via at least one transmit coil. The at least one receive channel is configured for receiving pilot tone data via at least one receive coil. The method comprises transmitting at least one pilot tone signal by controlling the at least one transmit channel. The method further comprises acquiring pilot tone data by controlling the at least one receive channel to receive pilot tone data. The method further comprises determining a motion state of the object using the pilot tone data.

[0030] A magnetic resonance imaging system is disclosed, the magnetic resonance imaging system comprising a memory storing machine executable instructions and pulse sequence commands configured for controlling the magnetic resonance imaging system to acquire magnetic resonance imaging data. The magnetic resonance imaging system further comprises a processor for controlling the magnetic resonance imaging system.

[0031] The magnetic resonance imaging system further comprises a pilot tone system. The pilot tone system comprises a radio frequency system comprising at least one transmit channel and at least one receive channel. The plurality of receive channels is configured for receiving pilot tone data via the at least one transmit channel. Execution of the machine executable instructions causes the processor to transmit at least one pilot tone signal by controlling the at least one transmit channel. Execution of the machine executable instructions further causes the processor to acquire pilot tone data by controlling the at least one receive channel to receive pilot tone data. Execution of the machine executable instructions further causes the processor to determine a motion state of the subject using the multi-channel pilot tone data.

[0032] Execution of the machine executable instructions further causes the processor to determine a current gradient pulse frequency using the pulse sequence commands. Execution of the machine executable instructions further causes the processor to detect subject motion having a periodicity within a predetermined range of the current gradient pulse frequency using the pilot tone data. Alternatively, subject motion can be detected by determining or detecting a correlation between the gradient pulse frequency and the pilot tone data. Execution of the machine executable instructions further causes the processor to provide a peripheral nerve stimulation warning signal in case the subject motion is detected.

[0033] The matching of subject motion to the gradient pulse frequency can be determined in several different ways. In one case, the frequency is determined from the periodicity of the gradient pulse waveform. This can be used to define a bandwidth, wherein, if motion is detected using the pilot tone data, a peripheral nerve stimulation warning signal is provided. There can also be a threshold level or predetermined threshold level set to determine whether the peripheral nerve stimulation is significant enough to warrant the provision of the warning signal.

[0034] The processor for controlling the pilot tone system can also be integrated into the subject support. For example, the pilot tone system can be fully contained within the subject support, and used to add PNS detection to an existing magnetic resonance imaging system by using a subject support with an integrated pilot tone system.

[0035] It is also disclosed that if a peripheral nerve stimulation warning signal is provided, execution of the machine executable instructions further cause the processor to perform any one of: selecting an alternative pulse sequence command, modifying the pulse sequence command, and cancelling execution of the pulse sequence command. All these alternatives can be beneficial as they can be used to reduce or eliminate peripheral nerve stimulation. This can lead to a higher degree of comfort of the subject in the magnetic resonance imaging system as well as reduced motion and thereby improved quality of any resulting magnetic resonance image.

[0036] It is also disclosed that the magnetic resonance imaging system further comprises a magnetic resonance imaging coil. The magnetic resonance imaging coil comprises the at least one pilot tone transmitting coil and / or the at least one receiving coil. In various examples, the coil can be integrated into a subject support of the magnetic resonance imaging system as well as into a used magnetic resonance imaging coil or antenna.

[0037] It is also disclosed that the magnetic resonance imaging system is configured for acquiring magnetic resonance imaging data in an imaging frequency range. The plurality of transmitting channels is configured for transmitting the unique pilot tone signal outside the imaging frequency range. For example, the pilot tone signal can be at a higher frequency than used for magnetic resonance imaging. This can be beneficial as it can enable simultaneous use of the magnetic resonance imaging system for acquiring magnetic resonance imaging data and for monitoring subject motion using the pilot tone signal.

[0038] It is also disclosed that the at least one transmitting channel is a plurality of transmitting channels. It should be noted that all embodiments disclosed in relation to multi-channel pilot tone signals and multi-channel pilot tone data can also apply to the magnetic resonance imaging system. For example, there can be a plurality of transmitting and receiving channels.

[0039] It is also disclosed that the at least one receiving channel is a plurality of receiving channels. This can be particularly beneficial as the distance from the subject to the receiving channel is very sensitive in determining the signal strength. If there is a plurality of receiving channels, it is easier to correctly position the subject such that the receiving channels will receive the pilot tone signal which can be interpreted as subject motion.

[0040] It should be understood that one or more of the preceding embodiments of the application can be combined as long as the combined embodiments are not mutually exclusive.

[0041] As will be appreciated by those skilled in the art, the various aspects of the present application can be implemented in software and / or hardware. The various aspects of the present application can be realized using one or more computer-readable media containing computer-readable instructions; a computer-readable medium can be, for example, but is not limited to, semiconductor memories, magnetic disk, optical disk, or CD-ROM. The computer-readable instructions can program a computer to carry out a method of the present application.

[0042] Any combination of one or more computer-readable medium can be utilized. The computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. "Computer-readable storage medium" as used in this paper encompasses any tangible storage medium which can store instructions which are executable by a processor of a computing device. The computer-readable storage medium can be referred to as a computer-readable non-transitory storage medium. The computer-readable storage medium can also be referred to as a tangible computer readable medium. In some embodiments, a computer-readable storage medium can also be able to store data which is able to be accessed by a processor of the computing device. Examples of computer-readable storage media include, but are not limited to: a floppy disk, a magnetic hard disk drive, a solid state hard disk, flash memory, a USB thumb drive, Random Access Memory (RAM), Read Only Memory (ROM), an optical disk, a magneto-optical disk, and the register file of the processor. Examples of optical disks include Compact Disks (CDs) and Digital Versatile Disks (DVDs), such as CD-ROM, CD-RW, CD-R, DVD-ROM, DVD-RW, or DVD-R disks. The term computer readable-storage medium also refers to various types of recording media capable of being accessed by the computer device via a network or communication link. For example, a data can be retrieved over a modem, over the internet, or over a local area network. Computer-executable instructions embodied on a computer-readable medium can be transmitted using any appropriate medium, including but not limited to wireless, wired, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

[0043] A computer-readable signal medium can include a propagated data signal with computer-executable instructions embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal can take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer-readable signal medium can be any computer-readable medium that is not a computer-readable storage medium and that can communicate, propagate or transport programming for use by or in connection with an instruction execution system, apparatus, or device.

[0044] "Computer memory" or "memory" is an example of computer readable storage media. Computer memory is any memory that a processor can access. "Computer storage" or "storage" is another example of computer readable storage media. Computer storage is any non-volatile computer readable storage media. In some embodiments, computer storage can also be computer memory or vice versa.

[0045] A "processor" as used herein encompasses an electronic component which acts to interpret and execute instructions. Recitations of a computing device including "processor" should be interpreted to allow that a computing device can include more than one processor or processing core. A processor can be a multi-core processor e.g. A processor can also refer to a collection of processors within a single computer system or distributed across multiple computer systems. The term computing device should also be interpreted to allow for a collection of computing devices or a network of computing devices each including one or more processors. The computer executable code can be executed by multiple processors that can be within the same computing device or even distributed across multiple computing devices.

[0046] Computer executable code can comprise machine executable instructions or a program which causes a processor to perform an aspect of the present application. Computer executable code for carrying out operations for aspects of the present application can be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the C programming language or similar programming languages. In some instances, the computer executable code can be in the form of a high level language or in a pre-compiled form and be used in conjunction with an interpreter which generates the machine executable instructions on the fly.

[0047] The computer executable code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0048] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0049] These computer program instructions can also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function / act specified in the flowchart and / or block diagram block or blocks.

[0050] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0051] A "user interface" as used herein is an interface that allows a user or operator to interact with a computer or computer system. A "user interface" can also be referred to as a "human interface device." A user interface can provide information or data to the operator and / or receive information or data from the operator. A user interface can enable input from an operator to be received by the computer and can provide output from the computer to the user. In other words, the user interface can allow an operator to control or manipulate a computer and the interface can allow the computer to indicate the effects of the operator's control or manipulation. Display of data or information on a display or graphical user interface is an example of providing information to an operator. Receipt of data by a keyboard, mouse, trackball, touchpad, pointing stick, graphics tablet, joystick, gamepad, webcam, headset, pedals, wired glove, remote control, and accelerometer are all examples of user interface components that enable receipt of information or data from an operator.

[0052] A "hardware interface" as used herein encompasses an interface that enables a processor of a computer system to interact with or control an external computing device and / or apparatus. The hardware interface can allow the processor to send control signals or instructions to the external computing device and / or apparatus. The hardware interface can also enable the processor to exchange data with the external computing device and / or apparatus. Examples of hardware interfaces include, but are not limited to: a universal serial bus, an IEEE 1394 port, a parallel port, an IEEE 1284 port, a serial port, an RS-232 port, an IEEE-488 port, a Bluetooth connection, a wireless local area network connection, a TCP / IP connection, an Ethernet connection, a control voltage interface, a MIDI interface, an analog input interface, and a digital input interface.

[0053] A "display" or "display device" as used herein encompasses an output device or user interface suitable for displaying images or data. The display can output visual, audio, and tactile data. Examples of displays include, but are not limited to: a computer monitor, a television screen, a touchscreen, a haptic electronic display, a Braille screen, a cathode ray tube (CRT), a storage tube, a bistable display, e-paper, a vector display, a flat-panel display, a vacuum fluorescent display (VF), a light-emitting diode (LED) display, an electroluminescent display (ELD), a plasma display panel (PDP), a liquid crystal display (LCD), an organic light-emitting diode display (OLED), a projector, and a head-mounted display.

[0054] Medical imaging data is defined herein as two-dimensional or three-dimensional data that has been acquired using a medical imaging scanner (X-ray system). A medical imaging scanner is defined herein as an apparatus suitable for acquiring information about the body structure of a patient and constructing a collection of two-dimensional medical image data or three-dimensional medical image data. The medical image data can be used to construct visualizations useful for a physician's diagnosis. The visualizations can be performed using a computer.

[0055] Magnetic resonance (MR) imaging data is defined herein as a measurement of radio frequency signals emitted by atomic spins recorded using an antenna of a magnetic resonance apparatus during a magnetic resonance imaging scan. Magnetic resonance data is an example of medical imaging data. A magnetic resonance imaging (MRI) image or MR image is defined herein as a reconstructed two-dimensional or three-dimensional visualization of anatomical data contained within magnetic resonance imaging data. The visualization can be performed using a computer. BRIEF DESCRIPTION OF DRAWINGS

[0056] In the following, a preferred embodiment of the present application will be described by way of example only and with reference to the drawings, in which:

[0057] Figure 1 An example of an X-ray system is illustrated;

[0058] Figure 2 a flowchart illustrating a method of operating an X-ray system is shown; Figure 1

[0059] Figure 3 a flowchart illustrating a further method of operating an X-ray system is shown; Figure 1

[0060] Figure 4 a flowchart illustrating a further method of operating an X-ray system is shown; Figure 1

[0061] Figure 5 an example of multi-channel pilot tone data is illustrated;

[0062] Figure 6 a further example of an X-ray system is illustrated;

[0063] Figure 7 an example of a motion state determined using multi-channel pilot tone data is illustrated;

[0064] Figure 8 an example of a magnetic resonance imaging system is illustrated;

[0065] Figure 9 a flowchart illustrating an example of a magnetic resonance imaging system is shown; and

[0066] Figure 10 an example of a software system for a medical system is illustrated.

[0067] List of reference signs

[0068] 100 X-ray system

[0069] 101 computed tomography gantry

[0070] 102 object

[0071] 103 bore

[0072] 104 object support

[0073] 105 imaging zone

[0074] 106 pilot tone system

[0075] 108 radio frequency system

[0076] 110 at least one transmit channel

[0077] 112 at least one receive channel

[0078] 114 at least one transmit coil

[0079] ​​​116 at least one receiving coil

[0080] 120 computer

[0081] 122 processor

[0082] 124 hardware interface

[0083] 126 user interface

[0084] 128 memory

[0085] 130 machine executable instructions

[0086] 132 control commands

[0087] 134 medical imaging data

[0088] 136 pilot tone signals

[0089] 138 pilot tone data

[0090] 140 motion state

[0091] 142 motion state model

[0092] 144 medical image

[0093] 200 controlling an x-ray system to acquire medical imaging data during acquisition of pilot tone data

[0094] 202 transmitting at least one pilot tone signal by controlling at least one transmitting channel

[0095] 204 acquiring pilot tone data by controlling at least one receiving channel

[0096] 206 determining a motion state of an object using the pilot tone data

[0097] 300 reconstructing a tomographic medical image using the medical imaging data

[0098] 302 correcting the reconstruction of the tomographic medical image using the motion state of the object

[0099] 400 gating the acquisition of the medical imaging data using the motion state of the object or modifying the acquisition of the medical imaging data using the motion state of the object

[0100] 500 multi-channel pilot tone data

[0101] 600 x-ray system

[0102] 602 ct or x-ray tube

[0103] 604 motion feedback monitor

[0104] 606 feedback patient monitor

[0105] 608 ECG trigger and respiration

[0106] 610 reconstruction including pilot data

[0107] 612 Al-machine learning module

[0108] 700 head position

[0109] 700' head position

[0110] 702 nose position

[0111] 702' nose position

[0112] 800 magnetic resonance imaging system

[0113] 804 magnet

[0114] 806 bore of the magnet

[0115] 808 imaging zone

[0116] 801 region of interest

[0117] 810 magnetic field gradient coil

[0118] 812 magnetic field gradient coil power supply

[0119] 814 magnetic resonance antenna

[0120] 816 radio frequency coil

[0121] 830 pulse sequence commands

[0122] 832 magnetic resonance imaging data

[0123] 834 magnetic resonance image

[0124] 836 time dependent gradient pulse frequency

[0125] 838 peripheral nerve stimulation warning signal

[0126] 900 acquiring magnetic resonance imaging data

[0127] 902 transmitting at least one pilot tone signal by controlling at least a portion of a plurality of transmit channels to transmit the at least one pilot tone signal

[0128] 904 acquiring pilot tone data by controlling at least a portion of a plurality of receive channels to receive the pilot tone data

[0129] 906 determining a motion state of a subject using the pilot tone data

[0130] 908 determining current gradient pulse frequency using pulse sequence commands

[0131] 910 detecting subject motion having periodicity within a predetermined range of the current gradient pulse frequency using pilot tone data

[0132] 912 providing peripheral nerve stimulation warning signal if subject motion is detected

[0133] 1000 pilot / RF reference coil array

[0134] 1002 gradient waveform

[0135] 1004 PNS detector / correlator

[0136] 1006 controller

[0137] 1008 neural network

[0138] 1010 gradient amplifier

[0139] 1014 PNS monitor DETAILED DESCRIPTION

[0140] Like numbered elements in these figures have equivalent functionality. Where the function is equivalent there is no need to discuss the already discussed element in subsequent figures.

[0141] Figure 1 An example of an X-ray system is illustrated. In this example, the X-ray system is a computed tomography system or CT system. However, Figure 1 This system depicted in the middle can also be a system for acquiring two-dimensional X-ray images, such as a conventional X-ray system or a fluoroscope, for example. The X-ray system 100 further comprises a computed tomography gantry 101 having a bore 103. Within the bore is shown a subject 102 resting on a subject support 104. The computed tomography gantry 101 has an imaging zone 105 in which medical imaging data can be acquired.

[0142] The x-ray system 100 is shown as having a pilot tone system 106. The pilot tone system 106 includes a radio frequency system 108 having at least one transmit channel 110 and at least one receive channel 112. The at least one transmit channel 110 is connected to at least one transmit coil 114. The at least one receive channel 112 is connected to at least one receive coil 116. In this example, the at least one transmit coil 114 and the at least one receive coil 116 are built into the object support 104. In other examples, the coils 114, 116 can be placed in alternative locations, such as around a support for the object 102, or even in some cases adjacent to or on the object.

[0143] The x-ray system 100 is shown as also including a computer 120. The computer 120 includes a processor 122. The processor 122 is intended to represent one or more processors or processing cores. The processor 122 can also be distributed across multiple computer systems 120. The processor 122 is shown as connected to a hardware interface 124. The hardware interface 124 enables the processor 122 to send and receive commands and data to and from other components of the x-ray system 100. In some cases, the hardware interface 124 can be, for example, a network interface, and enable the processor 122 to exchange data with other computer systems. The processor 122 is also shown as connected to a user interface 126 and a memory 128.

[0144] The memory 128 can be any combination of memory accessible to the processor 122. This can include things such as main memory, cache memory, and non-volatile memory such as flash RAM, hard drives or other storage devices. In some examples, the memory 128 can be considered a non-transitory computer readable medium.

[0145] The memory 128 is shown as having machine executable instructions 130. The machine executable instructions 130 enable the processor 122 to control the operation and functionality of the x-ray system. The memory 128 is shown as containing control commands 132. The control commands can be, for example, specific commands for a specific imaging protocol to acquire medical imaging data 134. The memory 128 is shown as containing medical imaging data 134 acquired by controlling the x-ray system with the control commands 132. In some examples, the control commands 132 can be incorporated into the machine executable instructions 130. The memory 128 is also shown as containing pilot tone signals 136 that can be transmitted using the at least one transmit channel 110.

[0146] The memory 128 is also shown to contain pilot tone data 138 received in at least one receiving channel 112 in response to the transmission of pilot tone signal 136. In some examples, the pilot tone signal 136 may be a plurality of unique pilot tone signals 136, which may be encoded, for example, in a manner different from those previously disclosed. The pilot tone data 138 may also be multi-channel pilot tone data. The memory 128 is also shown to contain motion state 140 derived from at least the pilot tone data 138. The memory 128 may, for example, contain motion state model 142.

[0147] Motion state model 142 can, for example, acquire pilot tone 138 and optionally pilot tone signal 136 as input to determine motion state 140. Motion state model 142 can be implemented in various ways. In one example, it can be, for example, a recurrent neural network, a convolutional neural network, a filter, or various other models. Memory 128 is also shown to contain medical image 144. Medical image 144 is reconstructed from medical imaging data 134.

[0148] Figure 2 The illustrated operation is shown. Figure 1 A flowchart of a method for using an X-ray system 100 is provided. First, in step 200, the X-ray system is controlled to acquire medical imaging data 134. While performing step 200, steps 202, 204, and 206 are also performed. In step 202, at least one pilot tone signal 136 is transmitted by controlling at least one transmit channel 110. Next, in step 204, pilot tone data 138 is acquired by controlling at least one receive channel 112. Finally, in step 206, the motion state 140 of the object 102 is determined using the pilot tone data 138.

[0149] Figure 3 The operation is illustrated. Figure 1 Alternative methods for the X-ray system 100. Figure 3 The method shown is similar to Figure 2 The method shown includes several additional steps. Steps 200, 202, 204, and 206 are performed as before. In this example, step 206 can be performed after steps 200, 202, and 204 have been fully executed. Next, in step 300, medical image 144 is reconstructed using medical imaging data 134. Finally, in step 302, motion state 140 is used to correct the reconstruction of medical image 144. This can be performed, for example, in different ways.

[0150] For example, if the motion state 140 is monitoring a heart or respiratory phase, the motion state 140 can separate the medical imaging data 134 into different bins and produce different images 144. In other examples, if the motion state 140 is more detailed, individual portions of the medical imaging data 134 can be corrected and used during the reconstruction of the medical images 144. Figure 3 The method in is an example of using the motion state 140 to perform retrospective correction of the medical images 144.

[0151] Figure 4 Fig. illustrates a further example of a method of operating Figure 1 the X-ray system 100. Figure 4 The method in is also similar to the method shown in Figure 2 Steps 200, 202, 204, 206 are performed as before. In the example of Figure 4 the motion state determination is done during the acquisition of the medical imaging data 134. In step 400, the medical imaging data is used to modify the acquisition of the medical imaging data. This can for example be used to change the alignment or the region imaged and to gate the acquisition of the medical imaging data.

[0152] A motion detection method is disclosed that can use different frequency, multi-frequency or wideband signal sources for X-ray or computed tomography (CT) scanners to correct for motion and use multiple RF reference signals to synchronize the scanner for cardiac imaging. The proposed method is able to replace ECG triggering, or additional data for improving the reconstruction, reducing the radiation dose and improving the workflow for autonomous imaging.

[0153] CT scans can use multiple input parameters and appropriate scan preparation. Depending on the body size, weight, patient position and anatomy to be scanned, the protocol is selected and modified to fit the patient. Usually, these data have to be entered manually. Specialized sensors are often used to measure physiological parameters (e.g. necessary to trigger a scan or to gate). It has recently been shown that relevant parameters can be derived from live video streams of cameras observing the patient during a scan. During a CT procedure, the patient is covered by clothing. Therefore, the camera images have limited use.

[0154] The pilot tone is a non-contact electromagnetic navigator that provides motion monitoring independent of MR or CT acquisition. The generation and acquisition of the pilot tone signal can be done using already existing system integration parts such as MR local coils that would be used for magnetic resonance imaging.

[0155] Potential benefits and / or applications can include one or more of the following:

[0156] - ECG-free detection of heartbeats and respiration

[0157] - Separation and quantification of head-body motion

[0158] - Derivation of triggers for cardiac and respiratory motion

[0159] - Application of MR LINAC radiotherapy

[0160] - Pilot tone / RF reference can be useful for accelerating patient preparation in order to increase quality and improve cost-effectiveness.

[0161] - Provide a replacement for ECG electrodes

[0162] - Reduce additional workflow

[0163] - Reduce X-ray dose

[0164] - Correct or compensate for motion due to uncooperative subjects

[0165] - Provide feedback to the patient

[0166] - Track subject motion through overlays and clothing.

[0167] Examples can use the pilot tone signal for X-ray or CT scanners. In one example, a digital pilot tone signal antenna is positioned / integrated in the patient table.

[0168] For autonomous imaging using X-rays, the system can continuously monitor the 3D position. When no motion / movement is detected or expected, the X-radiation / imaging is triggered. The system allows for body positioning or replacement of a certain position during imaging or between imaging sequences.

[0169] For CT, the X-ray beam is turned off during motion and the system detects the displacement from the original position, resulting in less dose.

[0170] In one example, the pilot tone signal can be monitored for active patient feedback. The patient / subject can reposition themselves, or the patient can use motion / position feedback monitors / sensors to align their position.

[0171] In another example, 3D / 4D information from the pilot tone data can be included in the reconstruction.

[0172] In another example, separate transmitting and receiving antennas and digital transmitters and receivers are used to allow for conversion of motion into complex 4D data sets.

[0173] In another example, the data can also feed a convolutional or recurrent neural network.

[0174] In another example, the pilot tone system is used with one or more additional motion detection systems, such as optical cameras, radar, or ultrasound acoustic detection.

[0175] Figure 5 An example of multi-channel pilot tone data 500 is illustrated. The shown pilot tone data 500 shows a number of plots of individual pilot tone signals that are measured. The cardiac signal and respiratory motion are well detected, but strongly depend on the individual antenna channel.

[0176] In an example, the local antennas (at least one receiving coil 116) receive a narrowband signal (pilot tone signal). Each antenna feeds an individual software defined receiver to a preamplifier. The complex signal is processed and motion appears differently in the individual signals as a change in amplitude or phase. The data is further processed and 3D / 4D information is converted to motion parameters.

[0177] The data (pilot tone data) can also feed a convolutional or recurrent neural network. A recurrent neural network (RNN) is a class of artificial neural network where connections between nodes form a directed graph along a sequence. This allows it to display dynamic temporal behavior to time series. Unlike feed-forward neural networks, RNNs can use their internal state (memory) to process sequences of inputs (here, different frequencies). This makes them suitable for tasks such as unsegmented, connected motion recognition or camera motion recognition.

[0178] Figure 6 A functional diagram of an X-ray system 600 is illustrated. In this example, the X-ray system 600 includes a CT or X-ray tube 602. Adjacent to the head of the subject 102 is a plurality of pilot reference receivers or a plurality of receiving channels 116. Further away from the subject 102 is a single pilot reference transmitter, which is a single transmitting channel 110 or at least one transmitting coil 114. There can also be a plurality of transmitting coils 114. There is a supplementary motion feedback monitor 604. The motion feedback monitor 604 can be used to display the current motion state to the subject 102 and can help the subject 102 to remain still. The X-ray system includes RF and SDR transceivers and feedback control including the pilot tone system 106. This pilot tone system provides data to a feedback patient monitor 606. The feedback patient monitor 606 provides images that are plotted by the motion feedback monitor 604. The pilot tone system 106 also provides data to an ECG trigger and respiratory trigger 608. The pilot tone system 106 also provides information to a reconstruction algorithm 610. An artificial or machine learning module 612 can be used to assist during reconstruction 610, as well as to train with data received via the pilot tone system 106.

[0179] Figure 7 An example of motion states 140 that can be derived from the multi-channel pilot tone data 500 is illustrated. Figure 7 Several position measurements are shown that are used with the multi-channel pilot tone data 500. In Figure 7In the illustrated example, a simple model is used to determine the distance of the subject's head from the plurality of receive coils 116. Plot 700 shows the position of the subject's head using this model. Plot 702 shows the orientation of the subject's nose from the data in plot 700. Likewise, plot 700' also shows the head position measured using the plurality of receive coils. Plot 702' shows the change in orientation of the subject's nose.

[0180] Figure 7 A simple example of how head motion can be detected using a collection of pilot tone transmitters and receivers is illustrated. Images 702 and 702' show a very simple head model in vector form pointing from the back of the head to the tip of the nose in a real coordinate system. The origin of the coordinate system represents the isocenter of the CT scanner. It is assumed that the back of the head is fixed to the patient table and cannot move.

[0181] Images 700 and 700' show a wireframe model of a 15 node pilot tone system. The positions of the nodes are derived from the spatial distribution of pilot tone transmitters and receivers around the subject's head.

[0182] Once the patient is placed on the patient table, the coordinate system in these images is zeroed. Any movement will now affect the signal strength and phase between different pilot tone transmitters and receivers. In the given model, the signal increase is mapped to the wireframe model by increasing the distance of the corresponding wireframe node from the (virtual) origin.

[0183] The wireframe is therefore distorted. This distortion is characteristic of head movement, for example, shaking the head will cause the signal to increase for some pilot tone transmitter and receiver combinations and decrease for others. This insight is used for the simplified head model. The position of the tip of the nose is calculated by a spatially weighted average of the signals of the 15 pilot tone nodes. In the given example, the volunteer turns his head to the right (negative y) from the neutral position (700, 702). In the wireframe model (700', 702'), this causes a tilt-like distortion. The head vector model therefore moves its tip to negative y.

[0184] Figure 8 An example of a magnetic resonance imaging system 800 is illustrated. Reference numbers that are repeated in this figure represent features or components that are equivalent to previously described features or components. Previously described components can not necessarily be described again.

[0185] The magnetic resonance imaging system 800 includes a magnet 804. The magnet 804 is a superconducting cylindrical magnet with a bore 806 through it. Use of different types of magnets is also possible, for example, use of both split cylindrical magnets and so-called open magnets is possible. A split cylindrical magnet is similar to a standard cylindrical magnet except that the cryostat has been split into two parts to allow access to the isoplanar plane of the magnet, such magnets can for example be used in conjunction with charged particle beam therapy. An open magnet has two magnet parts, one above the other, with a space between them large enough to receive a subject: the arrangement of the two parts is similar to that of a Helmholtz coil. Open magnets are popular because the subject is less constrained. Inside the cryostat of the cylindrical magnet is a collection of superconducting coils.

[0186] Within the bore 806 of the cylindrical magnet 804, there is an imaging zone 808 in which the magnetic field is strong and uniform enough to perform magnetic resonance imaging. A region of interest 809 is shown within the imaging zone 808. Magnetic resonance data is typically acquired for the region of interest. The subject 102 is shown supported by a subject support 104 so that at least a portion of the subject 102 is at least partially within the imaging zone 808 and the region of interest 809.

[0187] Also within the bore 806 of the magnet is a collection of magnetic field gradient coils 810 which are used to acquire preliminary magnetic resonance data to spatially encode magnetic spins within the imaging zone 808 of the magnet 804. The magnetic field gradient coils 810 are connected to a magnetic field gradient coil power supply 812. The magnetic field gradient coils 810 are intended to be representative. Typically, the magnetic field gradient coils 810 contain three separate sets of coils for spatially encoding in three orthogonal spatial directions. A magnetic field gradient power supply supplies current to the magnetic field gradient coils. The current supplied to the magnetic field gradient coils 810 is controlled as a function of time and can be ramped or pulsed.

[0188] Within the bore 806 of the magnet 804 is a magnetic resonance imaging antenna 814. The magnetic resonance imaging antenna 814 is shown to include a plurality of transmit coils 114 and a plurality of receive coils 116. The magnetic resonance imaging antenna 814 also includes a plurality of radio frequency coils 816 for performing magnetic resonance imaging. The radio frequency system 108 is also connected to the radio frequency coils 816. Figure 8 The arrangement shown enables acquisition of magnetic resonance imaging data while using a pilot tone system. In other examples, the radio frequency coils 816 can also be used as a plurality of transceiver coils 114 and / or a plurality of receive coils 116.

[0189] The radio frequency coil 816 can also be referred to as a channel or an antenna. The magnetic resonance antenna 814 is connected to the radio frequency system 108. The magnetic resonance antenna 814 and the radio frequency system 108 can be replaced by separate transmit and receive coils and separate transmitters and receivers. It is to be understood that the magnetic resonance antenna 814 and the radio frequency system 108 are representative. The magnetic resonance antenna 814 is also intended to represent a dedicated transmit antenna and a dedicated receive antenna. Likewise, the system 816 can also represent separate transmitters and receivers. The magnetic resonance antenna 814 can also have multiple receive / transmit elements and the radio frequency system 108 can have multiple receive / transmit channels. For example, if a parallel imaging technique such as SENSE is performed, the radio frequency system 108 can have multiple coil elements.

[0190] The radio frequency system 816 and the gradient controller 812 are shown as being connected to the hardware interface 124 of the computer system 128.

[0191] The memory 128 is shown as containing machine executable instructions 820. The machine executable instructions 820 enable the processor to control the magnetic resonance imaging system 800 as well as perform various data processing and image processing tasks. The memory 128 is also shown as containing pulse sequence commands 830 instead of control commands. The pulse sequence commands 830 are commands or data that can be converted into such commands for controlling the operation of the magnetic resonance imaging system 800. The memory 128 is also shown as containing magnetic resonance imaging data 832 that was acquired by controlling the magnetic resonance imaging system with the pulse sequence commands 830.

[0192] The memory 128 is also shown as containing magnetic resonance images 834 that were reconstructed from the magnetic resonance imaging data 832. The motion state 140 can be used in different ways. For example, the motion state 140 can be used to gate the acquisition of the magnetic resonance imaging data 832 as well as in the reconstruction of the magnetic resonance images 834.

[0193] The memory 128 can also contain time dependent gradient pulse frequencies 836 that were determined from the pulse sequence commands 830. The motion state 140 can be compared to the time dependent gradient pulse frequencies 836 to determine if peripheral nerve stimulation exists in the subject 102. A generated peripheral nerve stimulation warning signal 838 can exist if the motion state is above a certain level or above a certain amplitude related in the same frequency range as the detected motion.

[0194] Figure 9 A flow chart of a method of operating the magnetic resonance imaging system 800 is shown. First, in step 900, the magnetic resonance imaging system 800 is controlled with the pulse sequence commands 832 to acquire the magnetic resonance imaging data 834. When step 900 is performed, steps 902, 904, and 906 are also performed. Figure 8 A flow chart of a method of operating the magnetic resonance imaging system 800 is shown. First, in step 900, the magnetic resonance imaging system 800 is controlled with the pulse sequence commands 832 to acquire the magnetic resonance imaging data 834. When step 900 is performed, steps 902, 904, and 906 are also performed.

[0195] Next, in step 902, at least one pilot tone signal 136 is transmitted by controlling at least a portion of the plurality of transmission channels 110. Next, in step 904, pilot tone data 138 is acquired by controlling at least one reception channel 112.

[0196] Then, in step 906, the motion state 140 of the subject 102 is determined using the pilot tone data 138. This can be performed, for example, using a recurrent neural network. In a recurrent neural network, both the pilot tone data 138 and the pilot tone signal 136 can be input. In other cases, the motion state 140 can be determined from the multi-channel pilot tone data 138 alone. For example, periodic breathing or cardiac motion of the subject 102 can cause the pilot tone data 138 to have a frequency component equal to or approximately equal to the heart rate and / or the breathing rate. Thus, cardiac and / or breathing motion can be determined from the pilot tone data 138 alone.

[0197] In step 908, the time-dependent gradient pulse frequency 810 is determined using the pulse sequence commands 830. Next, in step 910, the motion state 140 is used to detect subject motion that is periodic within a predetermined range or correlation of the time-dependent gradient pulse frequency. For example, the motion state can be compared to the time-dependent gradient pulse frequency 810, or there can be a correlation that is calculated, for example, on the fly. Finally, in step 912, a peripheral nerve stimulation warning signal 812 is generated if subject motion is detected.

[0198] Another application is the detection of peripheral nerve stimulation during magnetic resonance imaging. It is possible to use the pilot tone signal acquired using the receive coil array and correlate it with the gradient waveform signal to detect and trigger for PNS detection. The whole matrix of receive coils is measured and correlated with the gradient waveform to detect PNS.

[0199] If certain thresholds are reached, the MR sequence is adapted to reduce PNS. The sequence is automatically adapted to patient comfort parameters. Measures: change of readout direction, change of sequence, gradient strength, repositioning of the patient. The data (multi-channel pilot tone data) can also be fed into a convolutional or recurrent neural network.

[0200] Strong gradients applied during an MRI examination can trigger peripheral nerve stimulation, causing movement of muscle fibers or entire muscles.

[0201] PNS

[0202] Uncomfortable for the patient

[0203] Horizontal is individual for the patient

[0204] Limitations are globally set, not considering individual susceptibility to PNS

[0205] Cannot communicate with disabled or sedated patients. No quantitative feedback to the operator.

[0206] Cannot be detected by camera-based methods

[0207] May cause MR artifacts due to motion

[0208] May cause accidental scans when the patient calls the operator.

[0209] Can be detected by using pilot tone signals acquired by the receive coil array used for PNS detection.

[0210] In general, the impact on the pilot tone signals caused by PNS is expected to be lower than the impact of e.g. breathing. Due to this, and in order to distinguish from other motions, the pilot tone signals acquired by the receive coil can be correlated with the gradient waveforms.

[0211] If certain thresholds are reached, the MR sequence is adapted to reduce PNS. The sequence is automatically adapted to patient comfort parameters. Possible measures are to change

[0212] the readout direction,

[0213] the sequence,

[0214] the gradient strength,

[0215] the patient's position / pose

[0216] Additional supplemental data, such as optical, camera, radar and ultrasound acoustic detection, can also be used.

[0217] For calibration purposes, the current MRI scanners feature a low-power transmit path independent of the body coil's transmit chain. Here, a small non-resonant coil is attached to the RF shield of the body coil. The transmit power for this coil is adjusted so that the RF signal is in the same order of magnitude as the RF signal originating from the spin system. Standard MRI coils are used for reception.

[0218] The pilot tone measurements can be interleaved or merged with the MR sequence. Tests show that this setup allows to detect motions caused by breathing. Further tests are performed to increase the sensitivity of the setup.

[0219] The above Figure 5An example of a pilot tone amplitude signal is illustrated. When looking at the phase of the acquired signal simultaneously, additional information can be obtained. The ideal position of the non-resonant coil is determined in a test to provide the most sensitive results of breathing and cardiac motion. In a given experiment, the optimal setup is to place the coil on top of the patient's sternum. The acquisition of pilot tones using all available RX coils allows for (limited) spatial sensitivity. This insight can be used to distinguish between different motion types.

[0220] It is possible that for PNS detection another position is more suitable, e.g. close to the long muscles of the patient's back.

[0221] The data (multi-channel pilot tone data) can also be fed to a convolutional or recurrent neural network. A recurrent neural network (RNN) is a class of artificial neural network where connections between nodes form a directed graph along sequences. This allows it to display dynamic temporal behavior to time series. Unlike feed-forward neural networks, RNNs can use their internal state (memory) to process sequences of inputs (here, different frequencies). This makes them suitable for tasks such as unsegmented, connected motion recognition or camera motion recognition.

[0222] Figure 10 A software algorithm and functional building blocks of the system are illustrated, which can for example be incorporated into a medical system such as Figure 8 The magnetic resonance imaging system of the medical system 800 shown. Block 1000 represents the pilot tone system and the array of radio frequency reference coils. Block 1002 represents the gradient waveforms from the pulse sequence commands. Block 1004 represents the software components that are the peripheral nerve stimulation detector and / or correlator 1004. The detector or correlator 1004 is able to take information about the gradient waveforms 1002 and information from the pilot tone data 1000 to detect whether there is a peripheral nerve stimulation. This is then fed into a controller 1006.

[0223] The controller 1006 can for example be equivalent to the processor 122. This information can then be forwarded or processed from the controller and fed to a neural network 1008, which can for example be equivalent to the neural network. The controller 1006 can use the detection of peripheral nerve stimulation to for example modify the behavior of the gradient amplifiers 1010 and can even modify the behavior or change the pulse sequence commands 832. This data can also be provided to a peripheral nerve stimulation monitor 1014. This can for example be provided via the user interface 126.

[0224] Figure 10 The following scheme shown illustrates how the pilot tone data can be processed and used.

[0225] - In a first step, pilot tone data is correlated with the gradient waveform. Depending on the level of signal correlation, the controller decides: correlation below a first threshold = no low PNS: sequence runs as planned

[0226] correlation below a second threshold = significant PNS: adaptation sequence

[0227] correlation above a second threshold = PNS at pain limit or expected significant image artifact: terminate scan by gradient amplifier interlock.

[0228] While the application has been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered illustrative or exemplary and not restrictive; the application is not limited to the disclosed embodiments.

[0229] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed application, from a study of the drawings, the disclosure, and the claims. In the claims, the word "comprising" does not exclude other elements or steps and the word "a" or "an" does not exclude a plurality. A single processor or other unit can fulfill the functions of several items recited in the claims. A combination of

[0230] While the application has been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered illustrative or exemplary and not restrictive; the application is not limited to the disclosed embodiments.

[0231] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the claims. In the claims, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. A single processor or other unit can fulfill the functions of several items recited in the claims. A combination of different hardware items can fulfill the functions of one item recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. A computer program can be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state storage medium supplied together with or as part of other hardware, but can also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. An X-ray system (100, 700) configured to acquire medical imaging data (134) from an object (102) at least partially within an imaging region (105), wherein, The X-ray system includes: Memory (128) storing machine-executable instructions (130); Processor (122), configured to control the X-ray system; and A pilot tone system (106), wherein the pilot tone system includes a radio frequency system (108), the radio frequency system including a plurality of transmit channels (110) and a plurality of receive channels (112), wherein the plurality of transmit channels are configured to transmit pilot tone signals (136) via a plurality of transmit coils (114); wherein the plurality of receive channels are configured to receive pilot tone data (138) via a plurality of receive coils (116); The processor is responsible for executing the machine-executable instructions. The pilot tone signal (202) is transmitted by controlling the plurality of transmission channels; The pilot tone data (204) is acquired by controlling the plurality of receiving channels; and The pilot tone data is used to determine (206) the motion state of the object (140, 700, 700', 702, 702').

2. The X-ray system according to claim 1, wherein, The radio frequency system is configured to encode each of the multichannel pilot tone signals using any of the following: frequency coding, phase coding, complex modulation, CDMA coding, and combinations thereof.

3. The X-ray system according to any one of claims 1-2, wherein, The state of motion is any one of the following: Object movement position (700, 700', 702, 702'); Motion vector; Object motion classification; Respiratory status; Cardiac function; A translation vector describing at least a portion of the object; Describing the rotation of at least a portion of the object; and Its combination.

4. The X-ray system according to any one of claims 1-2, wherein, The execution of the machine-executable instructions causes the processor to use any of the following to determine the motion state: A recurrent neural network is used, which is configured to receive the pilot tone data and the at least one pilot tone signal and to output the motion state. Detect the distance between each of the at least one receiving coil and the object; Use digital filtering; Use principal component analysis; and Its combination.

5. The X-ray system according to claim 1, in, The execution of the machine-executable instructions also causes the processor to control (200) the X-ray system to acquire the medical imaging data during the acquisition of the pilot tone data.

6. The X-ray system according to claim 1, wherein, The execution of the machine-executable instructions also causes the processor to: The medical imaging data is used to reconstruct (300) the medical image (144); and The motion state of the object is used to correct (302) the reconstruction of the medical image.

7. The X-ray system according to claim 5 or 6, wherein, The execution of the machine-executable instructions also causes the processor to use the motion state of the object to gate the acquisition of the medical imaging data (400).

8. The X-ray system according to claim 5 or 6, wherein, The execution of the machine-executable instructions also causes the processor to use the motion state of the object to modify (400) the acquisition of the medical imaging data.

9. The X-ray system according to any one of claims 1-2, wherein, The pilot tone system further includes at least one transmitting coil and / or at least one receiving coil.

10. The X-ray system according to claim 9, wherein, The X-ray system includes an object support (104) for supporting at least a portion of the object in the imaging region, wherein at least a portion of the at least one transmitting coil and at least a portion of the at least one receiving coil are integrated into the object support.

11. The X-ray system according to any one of claims 1-2, wherein, The X-ray system is an X-ray computed tomography system.

12. A computer program product comprising machine-executable instructions for execution by a processor (122), the processor being configured to control an X-ray system (100, 700), wherein, The X-ray system is configured to acquire medical imaging data (134) from an object (102) at least partially within an imaging region (105), wherein the X-ray system includes a pilot tone system (106), wherein the pilot tone system includes a radio frequency system (108), the radio frequency system including a plurality of transmit channels (110) and a plurality of receive channels (112), wherein the plurality of transmit channels are configured to transmit a plurality of pilot tone signals (136) via a plurality of transmit coils (114), wherein the plurality of receive channels are configured to receive pilot tone data (138) via a plurality of receive coils (116), wherein the execution of the machine-executable instructions instructs the processor to: The plurality of pilot tone signals are transmitted (202) by controlling the plurality of transmission channels; The pilot tone data is acquired (204) by controlling the multiple receiving channels to receive the pilot tone data; and The pilot tone data is used to determine (206) the motion state of the object (140, 700, 700', 702, 702').

13. A method of operating an X-ray system (100, 700), said X-ray system being configured to acquire medical imaging data (134) from an object (102) at least partially within an imaging region (105), wherein, The X-ray system includes a pilot tone system (106), wherein the pilot tone system includes a radio frequency system (108), the radio frequency system including a plurality of transmit channels (110) and a plurality of receive channels (112), wherein the plurality of transmit channels are configured to transmit a plurality of pilot tone signals via a plurality of transmit coils (114), wherein the plurality of receive channels are configured to receive pilot tone data via a plurality of receive coils (116), wherein the method includes: The plurality of pilot tone signals are transmitted (202) by controlling the plurality of transmission channels; The pilot tone data is acquired (204) by controlling the multiple receiving channels to receive the pilot tone data; and The pilot tone data is used to determine (206) the motion state of the object (140, 700, 700', 702, 702').

Images