Data transmission system for computed tomography scanners with a waveguide

Abstract

Device for transmitting data between a rotor (102) and a stator (103) wherein the rotor (102) has at least one data source (4), and wherein the stator (103) comprises at least one data sink (9) for evaluating the data, wherein at least one transmitter (7) and a waveguide (101) fed by the rotor (102) is provided and the transmitter (7) is designed to receive data from the data source (4) and to convert this data into an electromagnetic signal in the split waveguide (101); wherein at least one receiver (8) is provided on the side of the stator (103) which is designed to receive the electromagnetic signal from the split waveguide (101); wherein the receiver (8) is designed to convert the electromagnetic signal for transmission to the data sink (9); and wherein the split waveguide (101) is divided into two parts which are arranged at a small distance from each other around a central axis of rotation and which in cross-section has at least one web (105) extending along the longitudinal direction of the waveguide (101) and parallel to the axis of rotation.

Description

Technical field

[0001] The invention relates to a data transmission system for transmitting data between a rotating part and the stationary part of a rotary transmitter, for example for a computed tomography scanner, by means of a split hollow conductor. State of the art

[0002] A device for data transmission in computed tomography scanners is known from US Patent 6,433,631 B2. A stripline in the rotating part is supplied with the transmitter signal. A tap is provided on the stationary part, which is located at a short distance of approximately 1 mm from the stripline.

[0003] The transmission systems known from the state of the art are limited to data rates of max. 10 Gbit / s.

[0004] Other devices based on traditional waveguide systems used for transmitting high-frequency signals have significant limitations, especially when used in rotating systems. Existing solutions such as slotted waveguides offer limited bandwidth and high insertion loss, which impairs transmission quality.

[0005] The publication FR 2 522 884 A1 discloses a rotary high-frequency joint for signal transmission between two parts rotating relative to each other. It consists of a slotted, annular waveguide and a coupling element that extends through the slot into the waveguide to transmit signals without contact. The structure serves as a direct replacement for conventional slip ring transmitters.

[0006] German patent application DE 100 07 601 A1 describes a device for contactless data transmission in a computed tomography scanner. The transmission takes place between a rotating and a stationary part by means of an antenna arrangement. This arrangement includes a stripline on the rotating part and a capacitively coupled receiving antenna on the stationary part, which are positioned close to each other.

[0007] German patent application DE 20 2014 011 153 U1 discloses a slotted waveguide having two outer sections and a narrower central section connecting them, essentially corresponding to a slotted double-web waveguide. This arrangement is intended for data transmission along a linear path, for example to track-guided vehicles. Description of the invention

[0008] The object of the invention is to present a data transmission system which allows data transmission rates of up to several hundred Gbit / s and can be integrated into, for example, computed tomography scanners with minimal mechanical effort.

[0009] A solution to this problem according to the invention is specified in the independent claims. Further developments of the invention are the subject of the dependent claims.

[0010] A device according to the invention for transmitting data between the rotating part and the stationary part of a computed tomography scanner comprises at least one data source on the rotating part and at least one data sink on the stationary part. A data source can be, for example, an X-ray detector or the data acquisition system (data processing system), or a control unit or computer. A data sink can be a computer for evaluating and processing the data, but also another control unit or FPGA, etc.

[0011] Furthermore, the rotating part incorporates at least one transmitter and a first circular waveguide with a specific structure and optimized dimensions, fed by this transmitter. This waveguide enables low-loss transmission of high-frequency signals and reduces the dispersion effects caused by the rotation. The waveguide is designed to allow mechanical movement between the rotor and stator while efficiently transmitting electromagnetic power. Such a first transmitter receives data from the data source and converts it into a corresponding electromagnetic signal for transmission or coupling to the first waveguide. The stationary part also includes at least one receiver that receives the signal from the waveguide and extracts it. The receiver then converts the signals for transmission to the data sink.

[0012] The signal transmission from the rotating to the stationary part takes place via a signal line in the waveguide.

[0013] The signals can be modulated and / or encoded by the transmitting device according to the state of the art.

[0014] To avoid multipath propagation, mode-selective signal injection ensures that the transmitted signal remains clear and consistent. This technique minimizes the effects of the Doppler effect caused by the rotation of the rotary transformer and improves signal quality.

[0015] Mode-selective feed is achieved through optimized T-waveguide connections, with dimensions optimized for a better standing wave ratio (VSWR).

[0016] To minimize the channel impulse response and avoid multipath propagation, a single-mode wave is preferably used. Multimode propagation would lead to a high impulse response due to differing propagation speeds.

[0017] In the invention, the waveguide is slotted along its longitudinal axis. Both parts of the waveguide created by the slotting are arranged to be movable around a central axis of rotation at a small distance from each other. This is referred to as a waveguide system.

[0018] Depending on the required transmission characteristics, the waveguide can have a round, butterfly-shaped, T-shaped, double-T-shaped, or rectangular cross-section, with the rectangular cross-section being preferred. The profiles can also deviate from the basic shape by incorporating radii or similar features.

[0019] To minimize leakage losses at the waveguide slots, one or more ribs are incorporated into the waveguide's cross-section. These ribs concentrate the electromagnetic fields and reduce insertion loss. The rib structure optimizes mode propagation and minimizes losses by focusing the electromagnetic field in the center of the waveguide.

[0020] The bridges can be designed as single, double, or quadruple bridges. The shape and dimensions of the bridges must be optimized to reduce insertion loss and suppress unwanted modes.

[0021] One embodiment of the invention provides for at least one transmitting device in the stationary part and at least one receiving device in the rotating part. This embodiment also enables communication from the stationary part to the rotating part.

[0022] Another embodiment of the invention provides for several transmitting devices and several receiving devices, which are either each arranged on one of several parallel waveguides or on a waveguide divided into several segments.

[0023] Waveguide termination may be required for certain applications. This depends on the configuration and number of receivers and transmitters. Termination is achieved using pyramid-shaped microwave absorber material positioned within the waveguide.

[0024] A further embodiment of the invention provides a waveguide which transmits one or more signals from the rotating to the stationary part and / or from the stationary to the rotating part. The signals can use different carrier frequencies and / or be modulated differently and / or be encoded differently.

[0025] The modulation can be, for example, amplitude or frequency modulation, or a mixture of both such as QAM or similar.

[0026] In the case of simultaneous transmission of several signals in a waveguide, a signal / frequency crossover or similar device must be provided in both the transmitting and receiving equipment, which ensures decoupling between the signals and transmission directions through suitable measures such as frequency, phase selection or direction selection.

[0027] In a further embodiment of the invention, the transmitted signal is adjusted based on one or more selection parameters. These selection parameters can include, for example, signal strength, signal quality (such as noise), amplitude, jitter, etc.

[0028] In another embodiment, the invention is implemented as an array. Such an array comprises several waveguides which are fed with signals that are in a defined relationship to one another in order to obtain a specific radiation pattern as a whole. Such an array can be implemented with fixed phase relationships between the individual radiators or with variable phase ratios.

[0029] In one embodiment, a control unit is provided which, if present, adjusts or selects individual waveguide segments and their associated transmitting and receiving units according to predefined parameters. These predefined parameters for adjustment, selection, or choice include, for example, signal level, signal-to-noise ratio, bit error rate, propagation time, and / or phase shift relative to a reference signal or a position signal.

[0030] The waveguides are constructed from conductive material, such as metal, or from a substrate material coated with conductive material, such as plastic.

[0031] A further embodiment of the invention consists in the provision of an additional control unit for controlling bidirectional communication based on time windows, which specifies the time frame for each direction of communication.

[0032] A further embodiment of the invention consists in the provision of at least one circuit for frame and / or data recovery.

[0033] A further embodiment of the invention comprises a signal processor or FPGA in the transmitting unit, which divides the data onto several waveguides or waveguide segments, and an electronic circuit, e.g., also based on a signal processor or FPGA in the receiving unit, which combines the data back into a data stream.

[0034] A further embodiment of the invention comprises an amplifier directly at the signal coupling (feed-in point) and / or at the signal coupling (receiving point) in front of the receiving unit, wherein the gain of the amplifier is variable and the gain is adjusted based on measured or predetermined parameters.

[0035] A further embodiment of the invention comprises a discrete or integrated evaluation circuit which, based on various quality criteria such as the error rate, selects the receiving unit for forwarding the signal that best meets the quality criteria when several receiving units are involved.

[0036] For the sake of simplicity, this document refers to a transmission from the rotating part to the stationary part of a computed tomography scanner. Naturally, a device according to the invention can also be used in the reverse direction of transmission. Likewise, a device according to the invention can also be used in other applications for rotary transmission and also for linear transmission between two units moving relative to each other.

[0037] The transmission direction according to claim 1 was chosen from the rotor to the stator, as this corresponds to the most common application. However, transmission in the opposite direction or bidirectionally is also possible. Description of the drawings

[0038] The invention is described below by way of example, without limiting the general concept of the invention, with reference to the drawings. Fig. Figure 1 schematically shows a waveguide arrangement consisting of a stator and a rotor with a bridge and where b is greater than a. Fig. Figure 2 schematically shows a waveguide arrangement consisting of a stator and a rotor with a bridge and where a is greater than b. Fig. Figure 3 schematically shows a waveguide arrangement consisting of a stator and a rotor with several webs, where a is greater than b. Fig. Figure 4 schematically shows a waveguide arrangement consisting of a stator and a rotor with an absorber for terminating the RF signal. Fig. Figure 5 schematically shows a waveguide arrangement consisting of a stator and a rotor with a web and a bone-shaped waveguide cross-section. Fig. Figure 6 schematically shows a waveguide arrangement consisting of a stator and a rotor with a web and a circular waveguide cross-section. Fig. Figure 7 schematically shows a waveguide arrangement consisting of a stator and a rotor with several webs and a circular waveguide cross-section. Fig. Figure 8 schematically shows a waveguide arrangement consisting of a stator and a rotor with a web and a trapezoidal rounded waveguide cross-section. Fig. Figure 9 schematically shows a waveguide arrangement consisting of a stator and a rotor with several webs and a trapezoidal rounded waveguide cross-section. Fig. Figure 10 schematically shows an application of the waveguide transmission system in a computed tomography scanner. Reference symbol list 1 Gantry 2 Waveguide transmission system 3 X-ray tubes 4 X-ray detector 5 patients 6 columns 7 Transmitter 8 Receiver 9 computers 101 Waveguides 102 Rotor 103 Stator 104 gap 105 Bridge 112 Scheduling a wide stator inside b Distance rotor to stator c Width of bridge d Distance stator to bridge e distance between bridges

Claims

[1] Device for transmitting data between a rotor (102) and a stator (103) wherein the rotor (102) has at least one data source (4) and wherein the stator (103) comprises at least one data sink (9) for evaluating the data, wherein at least one transmitter (7) and a waveguide (101) fed by the rotor (102) is provided and the transmitter (7) is designed to receive data from the data source (4) and to convert this data into an electromagnetic signal in the split waveguide (101); wherein at least one receiver (8) is provided on the side of the stator (103) which is designed to receive the electromagnetic signal from the split waveguide (101); wherein the receiver (8) is designed to convert the electromagnetic signal for transmission to the data sink (9); and wherein the split waveguide (101) is divided into two parts which are arranged at a small distance from each other around a central axis of rotation and which in cross-section has at least one web (105) extending along the longitudinal direction of the waveguide (101) and parallel to the axis of rotation. [2] Device according to claim 1, wherein the waveguide (101) is formed with a single web (105) in the middle of the split waveguide (101) along a wide waveguide wall. [3] Device according to claim 1, wherein the split waveguide (101) is symmetrically designed with several webs (105). [4] Device according to one of the preceding claims, comprising at least one excitation point and at least one receiving point, each established by a T-waveguide connection, an electrical waveguide probe or a magnetic waveguide probe. [5] Device according to one of the preceding claims, wherein the device is configured such that the signals are modulated and / or encoded by the transmitter (7) and demodulated and / or decoded by the receiver (8). [6] Device according to one of the preceding claims, wherein the at least one split waveguide (101) acts as a transmitter, which is equipped at one end with the transmitter (7) and at the other end with at least one termination (112), wherein the at least one termination (112) is made of an absorbing material which is positioned inside the waveguide (101) and is able to attenuate microwaves. [7] Device according to claim 6, wherein the at least one termination (112) consists of a pyramid-shaped material that absorbs high-frequency electromagnetic waves. [8] Device according to one of the preceding claims, wherein the device is designed for propagation of a single-mode propagation which is due to the cross-sectional shape of the waveguide (101) and / or the excitation principle of the waveguide (101). [9] Device according to one of the preceding claims, wherein the at least one split waveguide (101) is connected to a receiver system, which preferably includes a coupling element and an electronic circuit. [10] Device according to one of the preceding claims, wherein the split waveguide (101) has a round, oval, butterfly-shaped, T-shaped, double T-shaped or square cross-section. [11] Device according to one of the preceding claims, wherein several transmitters (7) and several receivers (8) are provided, which are either each arranged on one of several parallel waveguides (101) or arranged on a waveguide (101) divided into several segments. [12] Device according to one of the preceding claims, wherein the waveguide (101) is configured to transmit one or more electromagnetic signals from the rotor (102) to the stator (103) and / or from the stator (103) to the rotor (102), wherein the electromagnetic signals use different carrier frequencies and / or are modulated differently and / or are encoded differently. [13] Device according to one of the preceding claims, wherein for the simultaneous transmission of several signals in the waveguide (101) both the transmitter (7) and the receiver (8) have a signal switch or similar, which is designed to provide decoupling between the electromagnetic signals and transmission directions, preferably by frequency, phase selection and / or direction selection. [14] Device according to one of the preceding claims, which is configured such that on the transmitter side (102) the electromagnetic signal is adjusted based on one or more selection parameters, preferably signal strength and / or signal quality. [15] Device according to one of the preceding claims, wherein a control unit is provided which is configured to adjust individual waveguide segments and the associated transmitters (7) and receivers (8) according to predetermined parameters, wherein the parameters for adjustment are preferably a signal level, a signal-to-noise ratio, a bit error rate, a propagation delay and / or a phase shift with respect to a reference signal or a position signal. [16] Device according to one of the preceding claims, wherein the waveguide (101) is made of an electrically conductive material, preferably metal, or of a carrier material coated with conductive material, preferably plastic. [17] Device according to one of the preceding claims, wherein at least one circuit for data or data frame recovery is provided. [18] Device according to one of the preceding claims, wherein several waveguide systems (2) are arranged side by side and preferably the transmitter (7) comprises a signal processor or FPGA configured to divide the data among several waveguide systems (2). [19] Device according to one of the preceding claims, wherein an amplifier is provided at the location of a signal coupling and / or a signal coupling upstream of the receiver (8), wherein the gain is variable and can be adjusted based on measured or predetermined parameters. [20] Device according to one of the preceding claims, wherein a discrete or integrated evaluation circuit is provided which, based on various quality criteria, preferably an error rate, selects the receiving unit for forwarding the electromagnetic signal which best meets the quality criteria when several receiving units are involved. [21] Device according to one of the preceding claims, wherein the device is designed for bidirectional communication between the rotor (102) and the stator (103), and a control unit is provided which specifies the time window for communication in the respective direction. [22] Computed tomography scanner comprising a device according to one of the preceding claims.

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