PATIENT COUCH WITH FLEXIBLE RF TRANSMITTING POWER DISTRIBUTION FOR A MAGNETIC RESONANCE TOMOGRAPHY SYSTEM

Abstract

A patient couch for a magnetic resonance tomography system and a magnetic resonance tomography system are provided. The patient couch includes a feed facility for radiofrequency energy having a plurality of conduction paths for feeding radiofrequency energy. The patient couch also includes a plurality of plug-in connectors for local coils having a transmit coil, and a distribution structure for the distribution of radiofrequency energy from the feed facility to the plug-in connectors.

Claims

1. A patient couch for a magnetic resonance tomography system, the patient couch comprising: a feed facility for radiofrequency energy, wherein the feed facility has a plurality of conduction paths for feeding radiofrequency energy; a plurality of plug-in connectors for local coils having a transmit coil and a first distribution structure for distribution of radiofrequency energy from the feed facility to the plurality of plug-in connectors, wherein at least one plug-in connector of the plurality of plug-in connectors is arranged in a movable fashion on the patient couch; and a position generator configured to determine a relative position of the at least one movable plug-in connector with respect to the patient couch.

2. The patient couch of claim 1, wherein the first distribution structure connects at least two conduction paths of the plurality of conduction paths of the feed facility electrically to a plug-in connector of the plurality of plug-in connectors for local coils.

3. The patient couch of claim 2, wherein the first distribution structure includes a power coupler configured to combine signals of the at least two conduction paths to form one signal on one signal line.

4. The patient couch of claim 2, wherein the first distribution structure has a plurality of flexible signal lines.

5. (canceled)

6. (canceled)

7. (canceled)

8. The patient couch of claim 1, wherein the feed facility is a first feed facility, and wherein the patient couch further comprises a second feed facility for radiofrequency energy, the second feed facility having a plurality of parallel conduction paths and a second distribution structure for the distribution of radiofrequency energy from the second feed facility to the plurality of plug-in connectors.

9. The patient couch of claim 3, wherein the feed facility is a first feed facility, and wherein the patient couch further comprises a second feed facility for radiofrequency energy, the second feed facility having a plurality of parallel conduction paths and a second distribution structure for the distribution of radiofrequency energy from the second feed facility to the plurality of plug-in connectors.

10. A magnetic resonance tomography system comprising: a patient couch comprising: a feed facility for radiofrequency energy, wherein the feed facility has a plurality of conduction paths for feeding radiofrequency energy; a plurality of plug-in connectors for local coils having a transmit coil and a first distribution structure for distribution of radiofrequency energy from the feed facility to the plurality of plug-in connectors, wherein at least one plug-in connector of the plurality of plug-in connectors is arranged in a movable fashion on the patient couch; and a position generator configured to determine a relative position of the at least one movable plug-in connector with respect to the patient couch; and a plurality of transmitting power outputs, wherein each transmitting power output of the plurality of transmitting power outputs has an electrical connection to a conduction path of the plurality of conduction paths of the feed facility for transmission of radiofrequency energy.

11. The magnetic resonance tomography system of claim 10, wherein the first distribution structure connects at least two conduction paths of the plurality of conduction paths of the feed facility electrically to a plug-in connector of the plurality of plug-in connectors for local coils, wherein the first distribution structure includes a power coupler configured to combine signals of the at least two conduction paths to form one signal on one signal line, and wherein the magnetic resonance tomography system further comprises a local coil having a transmit coil, the power coupler being provided in a housing of the local coil.

12. The magnetic resonance tomography system of claim 10, further comprising a local coil having a transmit coil, wherein the local coil includes a housing that is arranged in a predetermined position relative to a local coil connector.

13. The magnetic resonance tomography system of claim 12, wherein the magnetic resonance tomography system further comprises a controller, the controller being configured to control a transmitter pulse via the transmit coil of the local coil depending on the position of the at least one movable plug-in connector, captured by the position generator, relative to the patient couch.

14. The magnetic resonance tomography system of claim 10, wherein a plurality of electrical connections on the feed facility are configured in releasable fashion.

15. The magnetic resonance tomography system of claim 13, wherein a plurality of electrical connections on the feed facility are configured in releasable fashion.

16. The magnetic resonance tomography system of claim 10, wherein the patient couch is arranged in a patient tunnel of a field magnet of the magnetic resonance tomography system, wherein the first distribution structure is arranged in the vicinity of a conducting surface such that a reaction from an alternating electromagnetic field that is emitted by a local coil connected to a plug-in connector of the plurality of plug-in connectors is reduced.

17. The magnetic resonance tomography system of claim 10, further comprising a plurality of power sensors and a monitoring unit, wherein the plurality of power sensors are configured to monitor a radiofrequency energy flow through a plurality of electrical connections between the plurality of transmitting power outputs and the feed facility, and the monitoring unit is configured to monitor observance of SAR limit values by values captured by the plurality of power sensors.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG. 1 shows a schematic diagram of an embodiment of a magnetic resonance tomography system;

[0039] FIG. 2 shows a schematic diagram of an embodiment of a patient couch;

[0040] FIG. 3 shows a schematic of one embodiment of a power coupler for a patient couch;

[0041] FIG. 4 shows a schematic of one embodiment of a power coupler for a patient couch;

[0042] FIG. 5 shows a cross-section through a patient tunnel with an embodiment of a patient couch; and

[0043] FIG. 6 shows a schematic diagram of an embodiment of a control unit of a magnetic resonance tomography system.

DETAILED DESCRIPTION

[0044] FIG. 1 shows a schematic diagram of an embodiment of a magnetic resonance tomography system 1 including a patient couch 30.

[0045] The magnet unit 10 has a field magnet 11 that generates a static magnetic field B0 to align nuclear spins of samples or in a body of a patient 40 in an acquisition area. The acquisition area is arranged in a patient tunnel 16 that extends in a longitudinal direction 2 through the magnet unit 10. The field magnet 11 in question may be a superconducting magnet that may provide magnetic fields having a magnetic flux density of up to 3 T, or even higher, in the latest devices. For lower field strengths, however, permanent magnets or electromagnets with normal-conducting coils may also be used.

[0046] The magnet unit 10 has gradient coils 12 that are configured to overlay the magnetic field B0 with variable magnetic fields in three spatial directions for the spatial differentiation of the captured imaging regions in the sample volume. The gradient coils 12 are normally coils made of normal-conducting wires that may generate fields orthogonal to one another in the sample volume.

[0047] The magnet unit 10 also has a body coil 14 that is configured to give off a radiofrequency signal fed via a signal line into the sample volume, and to receive resonance signals emitted by the patient 40 and deliver the resonance signals via a signal line. The magnetic resonance tomography system according to one or more of the present embodiments has one or more local coils 50 that are arranged in the patient tunnel 16 close to the patient 40.

[0048] A control unit 20 supplies the magnet unit 10 with the various signals for the gradient coils 12 and the body coil 14 and evaluates the signals received.

[0049] Thus, the control unit 20 has a gradient control 21 configured to provide the gradient coils 12 with variable currents via feed lines. The variable currents provide the desired gradient fields in the sample volume on a temporally coordinated basis.

[0050] The control unit 20 has a radiofrequency unit 22 that is configured to generate a radiofrequency pulse with a predetermined time characteristic, amplitude, and spectral power distribution to excite a magnetic resonance of the nuclear spins in the patient 40. In this case, pulse powers in the kilowatt range may be achieved. The individual units are connected to one another via a signal bus 25.

[0051] The radiofrequency signal generated by the radiofrequency unit 22 is provided at a plurality of transmitting power outputs and fed to the patient couch 30 via a plurality of conduction paths 70 and distributed via a distribution structure 60 not visible in FIG. 1 to one or more local coils 50 and emitted into the body of the patient in order to excite the nuclear spins there.

[0052] The local coil 50 may then receive a magnetic resonance signal from the body of the patient 40; this is because the signal-to-noise ratio (SNR) of the local coil 50 is better on account of the small distance than in the case of being received by the body coil 14. The MR signal received by the local coil 50 is processed in the local coil 50 and forwarded to the radiofrequency unit 22 of the magnetic resonance tomography system 1 for evaluation and image acquisition. By preference, the distribution structure 60 and the conduction paths 70 are again utilized for this purpose, but separate signal connections or wireless transmission may also be provided. In one embodiment, special local coils or other antennas are provided for receiving.

[0053] FIG. 2 shows a possible embodiment of a patient couch 30 in a schematic diagram.

[0054] For the sake of clarity, ground conductors or return conductors of signal connections are not illustrated separately in FIG. 2. In this situation, the individual lines that stand for signal connections represent both cores required for an electrical connection, whether it be the inner conductor and the shield of a coaxial cable, the two cores of a symmetrical line, or the signal conductor and the ground plane of a stripline.

[0055] The patient couch has a distribution structure 60 for high frequency, the elements whereof are grouped together logically in FIG. 2 by the dashed line. In the embodiment illustrated, the distribution structure 60 has a feed socket 61, via which the conduction paths 70 may be connected to the patient couch 30. In one embodiment, the conduction paths 70 are connected without a socket 61 (e.g., connected directly in non-releasable fashion to the distribution structure 60).

[0056] The distribution structure 60 has signal lines 62 that connect the feed socket 61 electrically to plug-in connectors 63 for local coils for transmitting radiofrequency energy. The signal lines 62 may, for example, as already mentioned, be coaxial lines, symmetrical lines, or striplines on a flexible circuit board. In one embodiment, the distribution structure 60 consists entirely or for the most part of a flexible or rigid printed circuit board.

[0057] In one embodiment, the plug-in connectors 63 may, in one embodiment, be arranged in a fixed position on the patient couch 30. In one embodiment, one or more of the plug-in connectors 63 are arranged in movable fashion in the patient couch 30 such that the plug-in connectors 63 are movable, for example, in the plane of the patient couch 30 illustrated in FIG. 2 in the direction of a longitudinal extension of the patient couch 30 and/or also transversely thereto. This may be implemented, for example, by routing the plug-in connectors 63 in cross-bars or grooves in the patient couch 30 and a flexible distribution structure 60 including, for example, thin coaxial cables or a flex board.

[0058] In one embodiment, the patient couch 30 includes one or more position generators configured to capture the relative position of one or more movable plug-in connectors 63 in relation to the patient couch 30. The position generators may, for example, be configured to scan optical markers on the patient couch 30 or the plug-in connector 63 and thus to capture a relative position. Mechanical coding that is captured by switches or light barriers, or an electrical capture of a variable resistance, capacitance, or inductance and also other electronic devices in order to capture a distance or a relative position may be provided. The position generator is configured to transmit captured information via a signal connection to the controller 23 of the magnetic resonance tomography system 1. The signal connection is, for example, an electrical cable, a fiber optic cable, or a wireless connection. If the local coil 50 has a fixed connection to the local coil connector 51 (e.g., by the local coil connector 51 being arranged in the housing of the local coil 50), the position of the local coil 50 on the patient couch 30 is thereby also known to the controller 23.

[0059] In one embodiment, the controller 23 may be configured to optimize transmitter pulses emitted via the local coil 50 by using the information relating to the position of the local coil 50 and the information relating to the position of the patient couch 30 and thereby depending on the relative position of the plug-in connector 63 (e.g., by increasing the power level when the local coil 50 is located above non-sensitive body parts such as extremities).

[0060] In this situation, the feed socket 61 and/or the local coil sockets 63 may have any desired releasable connection systems for radiofrequency signals (e.g., coaxial connectors, surface contacts, spring contacts and/or also pin contacts, but also contactless connections such as a capacitive or inductive coupling).

[0061] The connection system 60 may also include power couplers 64 that make it possible to combine the signals and thereby also the power level from one or more signal lines 62 at one output. In this manner, the radiofrequency energy may be distributed on the conduction paths 70 onto a plurality of conduction paths 70, and therefore, thinner and more flexible lines may be used. As required, the plurality of conduction paths 70 may be merged by combination, and a high power level may be fed to a single local coil 50. In one embodiment, the power coupler 64 is provided not in the patient couch 30 itself but in the local coil 50. In one embodiment, the power coupler 64 is provided in a local coil connector 51, by which the local coil 50 may be connected to the patient couch 30.

[0062] FIG. 3 and FIG. 4 show possible exemplary embodiments of a power coupler.

[0063] The embodiment shown in FIG. 3 utilizes an inductive coupling or a transformer in order to merge the signals of two signal lines. The power coupler shown in FIG. 3 is not restricted to a single frequency. If, however, a ferrite core is used in order to increase the inductance, then the use in a magnetic resonance tomography system 1 may be rendered more difficult.

[0064] FIG. 4 shows a possible embodiment that is also non-critical in a strong magnetic field. In this situation, the waveguides having a length that corresponds to a quarter of the effective wavelength on the waveguide of the signal to be transmitted act as transformers, which are, however, frequency dependent.

[0065] In addition to the variants shown in FIGS. 3 and 4, a multiplicity of more complex networks consisting of resistances, inductances, and capacitances that permit a low-loss combination of two or more signals for one or more frequencies may also be provided as power couplers 64 in a patient couch 30 according to one or more of the present embodiments.

[0066] FIG. 5 shows a cross-section through a magnet unit 10, in the patient tunnel 16 whereof an embodiment of the patient couch 30 is arranged.

[0067] In this situation, the patient tunnel 16 has a conducting surface 17 that is arranged directly beneath the patient couch 30. Such types of conducting surfaces 17 may also be arranged between a wall of the patient tunnel 16 and other components such as gradient coil 12 or field magnet 11. In one embodiment, the conducting surface 17 is arranged in the patient couch 30 in the immediate vicinity of the wall of the patient tunnel 16.

[0068] Conducting surfaces exhibit the characteristic that electrical fields in the immediate vicinity have no electrical components that are tangential to the conducting surface. Accordingly, no significant voltages parallel to the conducting surface 17 may be induced even in signal lines 62 routed in the vicinity by the radiofrequency field in the patient tunnel 16. With the distribution structure 60 therefore being arranged in the immediate vicinity of the conducting surface 17, measures for suppressing induced waves or sheath currents may either be dispensed with entirely or be implemented in considerably simpler and considerably more cost-effective fashion Immediate vicinity in this situation is considered to be a distance between distribution structure 60 and conducting surface 17 of less than 1 cm, 5 cm, or 10 cm. Alternatively, immediate vicinity may be expressed in relation to the wavelength is less than one hundredth, one fiftieth, or one twentieth of the wavelength of the transmitter pulses and/or of the received magnetic resonance signals. In this situation, the distribution structure 60 is arranged in the immediate vicinity of the conducting surface 17 over an entire extent (e.g., length, width, or area) as far as possible (e.g., over at least 50, 80 or 90 percent of the extent). In one embodiment, the distribution structure lies entirely or partially on the conducting surface (e.g., electrically insulated).

[0069] FIG. 6 shows a schematic diagram of a control unit 20 of an embodiment of a magnetic resonance tomography system 1. The same objects are identified by the same reference characters as in FIG. 1.

[0070] The control unit 20 shown in FIG. 6 has a power sensor 26 that in each case captures a transmit power level that is output at a plurality of transmitting power outputs of the radiofrequency unit 22 to the conduction paths 70, and forwards a signal containing information about the transmit power levels output to a monitoring unit 27.

[0071] The monitoring unit 27 may, as shown in FIG. 6, be provided as part of a controller 23, or, for example, also as part of the radiofrequency unit 22, or independently of both. The monitoring unit 27 is configured to capture and to process the transmit power levels, and to compare values thus ascertained with one or more predetermined limit values. If a limit value is exceeded, the monitoring unit may output an alarm or directly interrupt an output of transmit power to the transmitting power outputs.

[0072] It is, for example, possible to monitor whether the power level at individual transmitting power outputs does not exceed predetermined limit values or the sum of the transmit power levels of a plurality of or all transmitting power outputs. The interruption may, for example, then be effected by the controller 23 via the signal bus 25.

[0073] Although the invention has been illustrated and described in detail using exemplary embodiments, the invention is not restricted by the disclosed examples. Other variations may be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.

[0074] The elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present invention. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims may, alternatively, be made to depend in the alternative from any preceding or following claim, whether independent or dependent. Such new combinations are to be understood as forming a part of the present specification.

[0075] While the present invention has been described above by reference to various embodiments, it should be understood that many changes and modifications can be made to the described embodiments. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description.