Patient positioning device with a motorized coil displacement unit

Abstract

Patient positioning device, the patient positioning device includes a patient table, the patient table includes a high-frequency coil for receiving magnetic resonance signals, wherein the patient positioning device includes a coil displacement unit, wherein the coil-shifting unit comprises a coil-shifting motor and a coil-shifting chain, wherein the coil displacement chain is coupled to the high-frequency coil at a coil-side coupling point, wherein the coil shifting chain is coupled to the coil shifting motor at a motor-side coupling point, wherein the coil displacement unit is configured to transmit a force from the coil displacement motor to the high-frequency coil via the coil displacement chain in order to displace the high-frequency coil along a displacement axis and / or to hold it in a predetermined position.

Description

[0001] The invention relates to a patient positioning device and a magnetic resonance device.

[0002] In medical technology, magnetic resonance imaging (MRI), also known as magnetic resonance tomography (MRI), is characterized by high soft tissue contrast. A patient is positioned on a patient table within a patient acquisition area of ​​a magnetic resonance scanner, where a main magnet generates a magnetic field. During a magnetic resonance scan, radiofrequency (RF) pulses are emitted into the scan area using one or more radio frequency coils according to a magnetic resonance sequence. These pulses generate an alternating magnetic field, thereby exciting nuclear spins in the patient. This excitation triggers magnetic resonance signals within the patient, which are received by one or more radio frequency coils. These magnetic resonance signals can then be used to reconstruct magnetic resonance images.

[0003] One possible embodiment of high-frequency coils is a spine coil, sometimes also called a back coil. Magnetic resonance devices are known in which the spine coil is placed in a designated recess on the top of the patient table. The length of the spine coil determines the measuring range, so the spine coil should be as long as possible to cover a large measuring range. However, manufacturing a long spine coil also incurs high costs.

[0004] The object of the present invention can be considered to be to provide a patient positioning device for efficiently moving a high-frequency coil along a displacement axis and / or holding it in a predetermined position. For example, this should enable a large measuring range. This object is achieved by the features of the independent claims. Advantageous embodiments are described in the dependent claims.

[0005] Accordingly, a patient positioning device for positioning a patient is proposed, comprising a patient table. The patient table includes a high-frequency coil for receiving magnetic resonance signals. The patient positioning device includes a coil displacement unit with a coil displacement motor and a coil displacement chain. The coil displacement chain is coupled, in particular connected, to the high-frequency coil at a coil-side coupling point and to the coil displacement motor at a motor-side coupling point. The coil displacement unit is configured to transmit a force from the coil displacement motor to the high-frequency coil via the coil displacement chain in order to displace the high-frequency coil along a displacement axis and / or to hold it in a predetermined position.

[0006] Preferably, the high-frequency coil is also configured for transmitting high-frequency signals. In particular, the high-frequency coil can be configured for transmitting excitation pulses of a magnetic resonance sequence and / or for receiving the resulting magnetic resonance signals. The high-frequency coil can, in particular, comprise one or more coil elements. A coil element can, for example, comprise a loop-shaped high-frequency antenna. The high-frequency coil can, in particular, be a spine coil. The high-frequency coil can, in particular, have the shape of a flat, especially rectangular, plate. The high-frequency coil can, in particular, have a length (parallel to the axis of displacement), a width (perpendicular to the axis of displacement), and a thickness (perpendicular to the axis of displacement), wherein the length and the width are significantly greater, in particular more than five times, and in particular more than ten times, than the thickness.

[0007] Often, the entire length of a spinal coil in a conventional setup is not utilized for a single MRI scan. Advantageously, the patient's body part being measured is located at the isocenter of the magnetic resonance device, as the homogeneity of the main magnetic field is particularly high there. Advantageously, the high-frequency coil, especially the spinal coil, of the proposed magnetic resonance device is only as large as necessary, and in particular, no larger than the area usable for receiving magnetic resonance signals. A smaller coil is advantageously less expensive to manufacture than a larger one.

[0008] Preferably, the distance, particularly the horizontal distance, between the coil-side coupling point and the motor-side coupling point changes along the displacement axis when the coil-displacement motor rotates. Preferably, when the coil-displacement motor rotates, the coil-displacement chain unwinds around a rotation axis of the coil-displacement motor.

[0009] Preferably, the patient positioning device comprises a support structure on which the patient table is movably mounted. Preferably, the predetermined position is a predetermined position relative to the support structure of the patient positioning device and / or to a magnetic resonance device encompassing the patient positioning device.

[0010] The supporting structure can be designed, in particular, as a substructure, frame, and / or base for the patient positioning device. Preferably, the patient positioning device includes a motor, particularly an electric one, to perform the movement, especially the displacement, of the patient table along the axis of displacement. Preferably, the displacement, particularly the motorized displacement, can be performed by an operator of the magnetic resonance imaging (MRI) device.

[0011] The specified position is preferably a measurement position in which a body part of the patient to be measured is located during a magnetic resonance imaging (MRI) scan. The specified position is preferably a position suitable for performing an MRI scan using the high-frequency coil arranged in the specified position. In the specified position, the high-frequency coil is preferably located in a measurement field where the main magnetic field of the MRI device exhibits sufficiently high homogeneity. The specified position is preferably a position of the high-frequency coil suitable for transmitting and / or receiving high-frequency signals for an MRI scan. Advantageously, in the specified position, the high-frequency coil covers a reception area for receiving MRI signals.

[0012] Preferably, the predetermined position is located near a patient's body part to be measured and / or within the field of view (FOV), optionally near a field of view, a magnetic resonance imaging (MRI) measurement, and / or near the isocenter of the MRI scanner. Advantageously, the distance between the field of view and the high-frequency coil and / or between the isocenter and the high-frequency coil is minimal when the high-frequency coil is located in the predetermined position along the displacement axis. For example, the predetermined position along the displacement axis is centered on a magnet unit of the MRI scanner. Advantageously, high-signal-to-noise ratio MRI signals can be acquired with the high-frequency coil when the high-frequency coil is located in the predetermined position.

[0013] By holding the counterpart in the receiving unit, the high-frequency coil is advantageously held in the predetermined position relative to the magnet unit, in particular temporarily fixed. By holding the counterpart in the receiving unit, the high-frequency coil is advantageously in the predetermined position relative to the magnet unit. Advantageously, by holding the high-frequency coil in the predetermined position, movement of the high-frequency coil relative to the magnet unit is prevented. By holding the high-frequency coil in the predetermined position, the high-frequency coil is preferably held relative to the magnet unit, in particular temporarily fixed.

[0014] The coil-shifting motor can, in particular, comprise an electric motor. An electric motor is typically a machine that converts electrical energy into mechanical energy. Preferably, it generates the force that is transmitted via the coil-shifting chain to the high-frequency coil. In converting the electrical energy into mechanical energy, the motor typically generates a rotary motion through the interaction of electric current and magnetic fields, which can be achieved by shifting the high-frequency coil. Electric motors are advantageously characterized by their high efficiency, reliability, and versatility.

[0015] The coil-shifting chain preferably comprises several interconnected chain links. The coil-shifting chain is preferably mechanically coupled to the high-frequency coil at the coil-side coupling point. The coil-shifting chain is preferably mechanically coupled to the coil-shifting motor at the motor-side coupling point.

[0016] Preferably, the patient table has a patient positioning surface for positioning the patient, wherein the axis of movement is aligned parallel to the patient positioning surface. Preferably, the axis of movement is horizontally aligned. Preferably, the axis of movement is aligned parallel to a movement axis of the patient table. Preferably, the coil displacement motor has a rotation axis that is aligned perpendicular to the axis of movement.

[0017] The patient positioning surface can be designed, in particular, as a tabletop. Preferably, the patient positioning surface is designed to support a patient. Preferably, the high-frequency coil is arranged beneath the patient positioning surface. In particular, during a magnetic resonance measurement, the patient positioning surface is located between the patient and the high-frequency coil. Preferably, the high-frequency coil has a main surface that is aligned parallel to the patient positioning surface. Preferably, the extent of the main surface of the high-frequency coil is determined by the length and width of the high-frequency coil. Advantageously, the distance between the high-frequency coil and a patient lying on the patient positioning surface is as small as possible in order to achieve a high signal-to-noise ratio of the received magnetic resonance signals.Preferably, the high-frequency coil is integrated into the patient table and / or fixed (but movable within it) and / or permanently installed. Preferably, the patient table comprises a housing that surrounds the high-frequency coil.

[0018] One possible embodiment of the patient positioning device provides that the coil displacement unit is designed to displace a part of the coil displacement chain located between the coil-side coupling point and the motor-side coupling point along a first displacement direction parallel to the displacement axis when the coil displacement motor is rotated in a first direction of rotation, wherein the coil displacement unit is designed to displace a part of the coil displacement chain located between the coil-side coupling point and the motor-side coupling point along a second displacement direction parallel to the displacement axis in a second displacement direction opposite to the first displacement direction when the coil displacement motor is rotated in a second direction of rotation opposite to the first displacement direction.

[0019] Preferably, the horizontal extent of the portion of the coil-shifting chain located between the coil-side coupling point and the motor-side coupling point changes during rotation of the coil-shifting motor. This portion of the coil-shifting chain can comprise several chain links. The number of chain links between the coil-side coupling point and the motor-side coupling point preferably depends on the (instantaneous) distance between the coil-side coupling point and the motor-side coupling point.

[0020] Preferably, the coil-shifting motor actively rotates during rotation. In particular, electrical energy is supplied to the coil-shifting motor to enable its rotation. Specifically, the coil-shifting motor consumes electrical energy to enable its rotation.

[0021] Preferably, the force for the displacement of the high-frequency coil along the displacement axis is caused by the rotation of the coil displacement motor and transmitted to the high-frequency coil via the coil displacement chain.

[0022] Another possible embodiment of the patient positioning device provides that the coil displacement unit includes a driving unit configured to drive the high-frequency coil in a first section when the patient table is moved along the displacement axis, and the coil displacement unit is configured to transmit a blocking, in particular braking, force from the coil displacement motor to the high-frequency coil via the coil displacement chain in a second section when the patient table is moved along the displacement axis, in order to hold the high-frequency coil in the predetermined position along the displacement axis.

[0023] Preferably, during the movement of the patient table along the axis of displacement in the first section, the high-frequency coil is connected to the patient table by means of the driving unit in such a way that the high-frequency coil is driven, and in particular pulled, along with the patient table. Preferably, the driving unit is fixedly arranged on the patient table.

[0024] To guide the high-frequency coil through the first section, the high-frequency coil can, for example, be pressed against the patient table, so that the resulting static friction between the patient table and the high-frequency coil guides the high-frequency coil along.

[0025] To guide the high-frequency coil through the first section, it can, for example, be locked into the patient table by means of a locking mechanism, such as a spring-loaded locking mechanism. Preferably, the locking mechanism is designed to release when a predetermined force is applied. This advantageously prevents damage should parts of the locking mechanism become jammed.

[0026] Preferably, the blocking force for holding the high-frequency coil in the predetermined position is caused by the coil displacement motor coming to a standstill, in particular by not rotating, and is transmitted to the high-frequency coil via the coil displacement chain.

[0027] Preferably, during the first section of movement of the patient table along the axis of movement, the coil displacement motor is in an idle state. The idle state of the coil displacement motor is preferably an operating condition in which the motor performs no mechanical work, i.e., it does not drive any load. In this operating state, preferably no significant force is transmitted to any connected component, in particular the high-frequency coil.

[0028] Preferably, the patient positioning device comprises a support structure on which the patient table is movably arranged, wherein the coil displacement motor is fixedly arranged on the support structure, in particular installed therein.

[0029] Preferably, the coil displacement chain is used to transmit a tensile force, particularly horizontal, and / or a compressive force, particularly horizontal, from the coil displacement motor to the high-frequency coil. Preferably, the tensile force and the compressive force act in opposite directions. Preferably, the coil displacement chain is designed as a drag chain and / or push chain.

[0030] A cable carrier, also known as an energy chain or cable drag chain, is preferably a mechanical guide element that can be used, in particular, to guide lines, cables and / or hoses safely and in an orderly manner along a movable axis. It protects the components guided within it from mechanical stress and at the same time allows their flexible movement.

[0031] A push chain is preferably a mechanical guide element designed to transmit forces in the direction of the displacement axis (longitudinal direction). Preferably, a push chain has chain links that interlock and / or stiffen under pressure. Preferably, the coil displacement chain is designed such that when the coil displacement chain moves from the motor-side coupling point to the coil-side coupling point, it stiffens (shear rigidity). Advantageously, a push chain is thus able to both pull and push.

[0032] Advantageously, a push chain enables linear movements with high stability and power transmission. Advantageously, the push chain is designed to absorb thrust forces. This allows the high-frequency coil to be positioned and / or held precisely.

[0033] Preferably, the coil-shifting chain comprises several chain links, each of which comprises several recesses, in particular grooves and / or openings, the coil-shifting motor having an axis of rotation and comprising a gear arranged coaxially to the axis of rotation, the gear comprising several teeth designed to engage in the recesses of the several chain links.

[0034] A gear is preferably a mechanical component consisting of a round disc with regularly arranged teeth. These teeth advantageously engage in corresponding recesses of the coil displacement chain to efficiently transmit rotary movements and forces.

[0035] Preferably, the coil displacement unit comprises a spring designed to compensate for any mechanical play between the coil displacement chain and the gear caused by switching between two directions of rotation, in particular between the first direction of rotation and the second direction of rotation.

[0036] Preferably, the spring mechanism cushions the engagement of the gear of the coil-shifting motor with the chain links of the coil-shifting chain. The spring mechanism can, for example, include a tension spring to cushion the engagement of the gear of the coil-shifting motor with the chain links of the coil-shifting chain.

[0037] Furthermore, a magnetic resonance device is proposed comprising a previously described patient positioning device with a patient table having a patient positioning surface and a magnetic unit, wherein the magnetic unit surrounds a patient acquisition area of ​​the magnetic resonance device. The patient positioning device is configured to move the high-frequency coil and the patient positioning surface together in a first section along the displacement axis, in particular by means of the coil displacement unit, wherein the coil displacement unit is configured to hold the high-frequency coil in the predetermined position relative to the magnetic unit when the patient positioning surface is moved along the displacement axis in a second section.

[0038] The magnetic unit can, in particular, comprise a main magnet (for generating a main magnetic field), especially a superconducting one, and / or a gradient coil unit (for generating magnetic field gradients). The main magnetic field can, for example, have a strength between 0.5 and 12 Tesla. Furthermore, the magnetic unit can, in particular, comprise a body coil (for transmitting and / or receiving high-frequency signals). Preferably, the main magnet and / or the gradient coil unit and / or the body coil are fixedly installed in the magnetic unit.

[0039] The patient reception area can be configured, in particular, as a bore in the magnetic unit. The patient reception area can also be configured, in particular, as a cavity in the magnetic unit. The patient reception area can be, in particular, cylindrical, i.e., have the shape of a cylinder, especially a circular cylinder. The central axis of such a cylinder can be, in particular, aligned parallel to the axis of displacement. The patient reception area can be bounded, in particular, in a circumferential direction by a housing wall of the magnetic unit. The patient reception area can be bounded, in particular, in a longitudinal direction by openings of a bore in the magnetic unit that characterizes the patient reception area. Advantageously, the patient can be brought into the patient reception area through these openings.

[0040] Preferably, holding the high-frequency coil in the predetermined position keeps it within the field of view, optionally close to the field of view, and / or close to the isocenter of the magnetic resonance device. Preferably, in the first movement phase, the high-frequency coil is moved along the displacement axis to the height of a field of view of a magnetic resonance measurement and / or an isocenter of the magnetic resonance device and then held there. Advantageously, by holding the high-frequency coil in the predetermined position with a relatively short high-frequency coil, a relatively large, particularly posterior (located below the patient), measurement range along the displacement axis can be covered; the size of the measurement range then depends in particular on the length of the second movement phase, in which the high-frequency coil is held in the predetermined position.

[0041] Preferably, the second section connects directly to the first section. Preferably, the patient support surface and the high-frequency coil are configured to move together along the displacement axis within the patient acquisition area of ​​the magnetic resonance device in the first section. Preferably, the patient support surface and the high-frequency coil are configured such that, in the second section, the patient support surface continues to move along the displacement axis while the high-frequency coil remains stationary.

[0042] The first part of the movement of the patient positioning surface can, in particular, involve moving the patient table, and especially a patient lying on it, from the outside through a first opening into the patient reception area. The second part of the movement of the patient positioning surface can, in particular, involve moving the patient table, and especially the patient lying on it, beyond a predetermined point. Preferably, by this movement, the patient table can be moved out of the patient reception area again through an opening opposite the first opening along the axis of movement.

[0043] Advantageously, the high-frequency coil is moved into the predetermined position and held there. In particular, the high-frequency coil is housed within the patient table. Preferably, before the patient is moved into the table, the high-frequency coil is positioned in a forward position, particularly as far forward as possible. When the high-frequency coil reaches the predetermined position during the first movement phase, it advantageously remains there. During a further longitudinal movement of the patient support surface along the axis of displacement, the high-frequency coil remains stationary during the second movement phase. Thus, in this second movement phase, there is a relative movement between the patient support surface and the high-frequency coil.

[0044] Preferably, the high-frequency coil remains in this predetermined position, and only when the patient support surface reaches a maximum possible scan position of the high-frequency coil during extension, does the patient support surface, together with the high-frequency coil, leave the bore of the magnet again until it reaches, for example, a longitudinal end position, in particular a transfer position, of the patient table, especially on a frame of the patient support device.

[0045] Preferably, during the movement of the high-frequency coil and the patient support surface in the first section, the coil displacement motor is actively rotated, in particular by consuming externally supplied energy, for example electrical energy, to perform the rotation. Preferably, this active rotation generates a force that is transmitted via the coil displacement chain to the high-frequency coil in order to move the high-frequency coil along the displacement axis.

[0046] Preferably, the coil displacement motor does not rotate during the movement of the patient support surface in the second section, so that the high-frequency coil is held in the predetermined position relative to the magnet unit.

[0047] Another possibility involves the coil displacement motor being in idle mode during the movement of the high-frequency coil and the patient support surface in the first section, and the high-frequency coil being connected to the patient support surface (particularly by means of the drive unit) in such a way that the high-frequency coil is moved, or in particular pulled, along with it. Preferably, the coil displacement motor is blocked, or in particular braked, during the movement of the patient support surface in the second section, so that the high-frequency coil is held in the predetermined position relative to the magnet unit.

[0048] Further advantages, features, and details of the invention will become apparent from the exemplary embodiments described below and from the drawings. Corresponding parts are designated with the same reference numerals in all figures.

[0049] They show: Fig. 1-4 a magnetic resonance device with a patient positioning device in various operating states, Fig. 5 a section of a coil-shifting chain, Fig. 6 a coil-shifting motor with a gear coupled to a coil-shifting chain.

[0050] In Fig. Figure 1 schematically depicts a magnetic resonance imaging (MRI) device 10. The MRI device 10 comprises a magnetic unit 11, which includes a main magnet 12 for generating a strong and, in particular, time-constant main magnetic field. The MRI device 10 also includes a patient reception area 13 for receiving a patient. In the present embodiment, the patient reception area 13 is cylindrical and is cylindrically surrounded in one circumferential direction by the magnetic unit 11. The patient reception area 13 is formed as a bore in the magnetic unit. The MRI device 10 includes a patient positioning device 100 with a support structure 15 and a patient table 16 arranged thereon, onto which a patient can be placed.The patient table 16 can be moved into and out of the patient reception area 13 along a displacement axis parallel to the (horizontal) z-axis. Preferably, the part of the patient from which a magnetic resonance image is to be generated is placed in a measurement field 14. The measurement field 14 is typically located in the center of the magnet unit 11. The measurement field 14 is characterized by a particularly homogeneous main magnetic field. High homogeneity of the main magnetic field is particularly necessary to ensure high spatial resolution of the magnetic resonance signals. The field of view (FOV) of the magnetic resonance measurement is preferably located in the measurement field 14. Preferably, the measurement field includes the isocenter of the magnetic resonance device 10.

[0051] The magnet unit 11 further comprises a gradient coil unit 18 for generating magnetic field gradients, which are used for spatial encoding during imaging. The gradient coil unit 18 is controlled by a gradient control unit 19 of the magnetic resonance device 10. The magnet unit 11 also includes a whole-body coil 20, which is permanently integrated into the magnetic resonance device 10. The whole-body coil 20 is controlled by a high-frequency antenna control unit 21 of the magnetic resonance device 10 and transmits high-frequency magnetic resonance sequences into an examination space, which is essentially formed by the patient acquisition area 13, in particular the measurement field 14, of the magnetic resonance device 10. This excites atomic nuclei in the main magnetic field generated by the main magnet 12. Magnetic resonance signals are generated by the relaxation of the excited atomic nuclei.

[0052] The magnetic resonance device 10 further comprises a high-frequency coil 26, which is configured here as a spinal coil, for receiving the magnetic resonance signals. The high-frequency coil 26 is arranged in the patient table 16. It is located below a patient support surface 17 on which the patient is positioned. The patient support surface 17 can, in particular, be a surface of a tabletop of the patient table 16.

[0053] The high-frequency coil 26 has a thickness in the y-direction that is significantly smaller (in particular by at least a factor of 5 or at least a factor of 10) than its length in the z-direction. The width of the high-frequency coil 26 would then be its extent perpendicular to the y- and z-directions, i.e., in the viewing direction perpendicular to the plane of the drawing.

[0054] The magnetic resonance device 10 includes a system control unit 22 for controlling the main magnet 12, the gradient control unit 19, and the high-frequency antenna control unit 21. The system control unit 22 centrally controls the magnetic resonance device 10, for example, by performing a predetermined magnetic resonance sequence. The system control unit 22 also includes an evaluation unit (not shown) for evaluating the magnetic resonance signals acquired during the magnetic resonance examination.

[0055] Furthermore, the magnetic resonance device 10 includes a user interface 23, which is connected to the system control unit 22. Control information, such as imaging parameters, as well as reconstructed magnetic resonance images, can be displayed on a display unit 24, for example, on at least one monitor, of the user interface 23 for medical personnel. The user interface 23 also includes an input unit 25, by means of which information and / or parameters can be entered by the medical personnel during a measurement procedure.

[0056] Based on the Fig. Figures 1 to 4 show that the patient positioning surface 17 and the high-frequency coil 26 in the present example are configured to be moved together in a first section along a displacement axis within the patient acquisition area 13 of the magnetic resonance device 10, wherein the patient positioning device 100 comprises a coil displacement unit configured to transmit a force to the high-frequency coil 26 in order to displace the high-frequency coil along a displacement axis and / or to hold it in a predetermined position relative to the magnet unit 11 when the patient positioning surface 17 is moved in a second section along the displacement axis. The displacement axis is aligned parallel to the z-axis. For clarity, in Fig. 2 to 4 on the representation of some in Fig. 1 of the components shown has been omitted.

[0057] In Fig. In Figure 1, the patient table 16 is in a state where it is maximally retracted. In this state, a patient can be positioned particularly easily on the patient positioning surface 17. The depicted position of the patient table 16 can therefore also be referred to as the patient transfer position. In this position, the high-frequency coil 26 is located in its foremost position within the patient table 16. The distance between the high-frequency coil 26 and the end face of the patient table 16 closest to the magnet is minimal.

[0058] The patient positioning device 100 comprises a coil displacement unit, which includes a coil displacement chain 27 and a coil displacement motor 28. The coil displacement motor 28 can, in particular, be fixedly arranged on the support structure 15 and has an axis of rotation that is oriented perpendicular to the displacement axis. The coil displacement chain 27 is coupled, in particular connected, to the high-frequency coil 26 at a coil-side coupling point Sc and coupled, in particular connected, to the coil displacement motor 28 at a motor-side coupling point Sm. The coil displacement unit is configured to transmit a force from the coil displacement motor 28 to the high-frequency coil 26 via the coil displacement chain 27 in order to displace the high-frequency coil along the displacement axis and / or to hold it in a predetermined position.The coil-shifting unit further comprises a winding unit 29, which is configured to wind up the coil-shifting chain 27.

[0059] When the patient table 16 is moved through the right opening of the bore into the patient reception area 13, it reaches the point in the Fig. Position 2 shown. In this first section of the movement, the high-frequency coil 26 is moved together with the patient support surface 17 in the direction R along the displacement axis, i.e. the relative position of high-frequency coil 26 and patient support surface 17 does not change.

[0060] To ensure the joint movement of the high-frequency coil 26 and the patient support surface 17 along the displacement axis of the in Fig. 1 state shown in the in Fig. To carry out the state shown in section 2, two alternatives are particularly possible: According to a first alternative, the coil-shifting motor 28 drives the coil-shifting chain 27 and the patient positioning surface 17, which is moved, for example, by means of a belt drive, at the same speed until the high-frequency coil 26 reaches the point where it is located. Fig. The predetermined position shown in Figure 2 is reached. To achieve this, the coil-shifting motor 28 rotates in a first direction (counterclockwise in this view) to shift the coil-shifting chain 27 (specifically, the portion of the coil-shifting chain 27 located between the coil-side coupling point Sc and the motor-side coupling point Sm at any given time) together with the high-frequency coil 26 connected to the coil-shifting chain 27 in the positive z-direction. The coil-shifting motor 28 actively rotates during this process. The force required to shift the high-frequency coil 26 along the displacement axis is generated by the rotation of the coil-shifting motor 28 and transmitted to the high-frequency coil 26 via the coil-shifting chain 27.

[0061] According to a second alternative, the coil displacement unit comprises a carriage unit (not explicitly shown here), which is arranged, in particular, fixedly relative to the patient support surface 17, and is configured to carry the high-frequency coil 26 along the first section of the movement when the patient support surface 17 moves along the displacement axis. For this purpose, the high-frequency coil 26 can, for example, engage in the patient table 16, in particular in a tabletop of the patient table 16, to pull the high-frequency coil 26 along in the first section. During the movement of the patient support surface 17 along the displacement axis in the first section, the coil displacement motor 28 is in an idle position.

[0062] In Fig. Figure 2 shows the situation in which the high-frequency coil 26 is located in the specified position relative to the magnet unit 11, characterized here by the fact that the high-frequency coil 26 is located in the measuring field 14 of the magnetic resonance device 10. This position can, in particular, represent the beginning of the scan area of ​​the patient table 16.

[0063] For example, the patient is positioned on the patient positioning surface 17 such that his head is located in the front area of ​​the patient positioning surface 17, i.e., the high-frequency coil 26 is located in the Fig. The position shown in Figure 2 is directly below the patient's head. In this position, magnetic resonance signals can be acquired to generate an MR image of the patient's head. The high-frequency coil 26 is held in this position by means of the coil displacement unit.

[0064] If the patient support surface 17 (together with the patient) is moved further along the axis of displacement in direction R during this second section of the movement, the high-frequency coil 26 remains stationary relative to the magnet unit 11. To achieve this, the high-frequency coil 26 is held in the predetermined position. This can be done, in particular, according to the following alternatives: According to the first alternative, the coil shifting motor 28 stops, so that the coil shifting chain 27 and the high-frequency coil 26 also stop.

[0065] According to the second alternative, further movement of the high-frequency coil 26 along the patient support surface 17 is prevented by blocking or braking the coil displacement motor 28. The coil displacement unit is thus designed, when the patient table moves along the displacement axis in the second section, to transmit a blocking force from the coil displacement motor 28 to the high-frequency coil 26 via the coil displacement chain 27, in order to hold the high-frequency coil 26 in the predetermined position along the displacement axis.

[0066] While the high-frequency coil 26 is held in the predetermined position during the second part of the movement, the patient positioning surface 17 reaches the position indicated in Fig. Position 3 shown. This position can, in particular, represent the end of the scan area of ​​the patient table 16. Advantageously, a relatively large scan area can be covered with only a relatively short high-frequency coil 26, since the position of the patient on the patient support surface 17 relative to the high-frequency coil 26 is variable.

[0067] Even when the patient support surface 17 (together with the patient) is moved back along the displacement axis, but now in the opposite direction R, the high-frequency coil 26 remains stationary relative to the magnet unit 11. Only after the patient support surface 17 has moved back along the axis of displacement, but in the opposite direction R, does the high-frequency coil 26 remain stationary relative to the magnet unit 11. Fig. Once the position shown in section 4 has been reached, the high-frequency coil 26 is moved again and, after a further retraction of the patient table 16 together with the patient positioning surface 17, reaches the position shown in Fig. Position 1 shown. The movement of the high-frequency coil 26 back to this position can be carried out in particular according to the following alternatives: According to the first alternative, the coil displacement motor 28 switches on again at a certain point when the patient table 16 is retracted and pulls out the high-frequency coil 26 at the same speed as the patient support surface 17 itself. The coil displacement unit is thus designed, when the coil displacement motor 28 rotates in a second direction (clockwise in this view), to displace the part of the coil displacement chain 27 located between the coil-side coupling point Sc and the motor-side coupling point Sm in the negative z-direction.

[0068] According to the second alternative, at that certain point the brake of the coil displacement motor 28 is released and the high-frequency coil 26 is retracted by the driving unit, in particular by a detent in the table top.

[0069] Fig. Figure 5 shows a top view of a section of a coil-shifting chain 27 with four chain links 30. Each chain link has several recesses 31. The recesses 31 can be designed, for example, as grooves and / or openings.

[0070] Fig. Figure 6 shows a side view of a coil-shifting motor 28 and a coil-shifting chain 27. The coil-shifting motor 28 comprises a gear 33 with several teeth 34, in particular a pinion, and has a pivot axis 32 about which the gear 33 can rotate during operation.

[0071] The teeth 34 engage in the recesses 31 of the coil displacement chain 27, so that with a rotation of the coil displacement motor 28, the coil displacement chain 27 is moved to the left and right, depending on the direction of rotation. This makes it possible, in particular, to move the high-frequency coil 26.

[0072] Preferably, the engagement of the teeth 34 in the recesses 31 is (slightly) spring-loaded to compensate for and / or equalize any play that may occur between the gear 33 and the coil-shifting chain 27 during engagement. This can be implemented, for example, by a simple tension spring.

[0073] Advantageously, the use of an active drive via the coil displacement motor 28 enables fully automated displacement of the high-frequency coil 26. In particular, manual intervention by the operating personnel can be avoided when performing a magnetic resonance examination in which different nuclei are measured (Multinuclear Option, abbreviated: MNO).

[0074] Furthermore, the coil displacement chain 27 can also be used to route the cable of the high-frequency coil 26. In addition, the position of the high-frequency coil 26 can be determined at any time via software, which is advantageous for safety reasons, particularly for SAR calculations. Moreover, this solution requires very little installation space below the patient table 16 and can be implemented in such a way that it is not visually apparent that such a drive is installed in the patient positioning device 100. The minimal space requirements also facilitate integration into existing patient positioning device designs.

[0075] Finally, it should be noted once again that the patient positioning device and the magnetic resonance device described in detail above are merely exemplary embodiments which can be modified in various ways by those skilled in the art without departing from the scope of the invention. Furthermore, the use of the indefinite articles "a" or "an" does not preclude the possibility that the features in question may be present multiple times. Likewise, the term "unit" does not preclude the possibility that the components in question consist of several interacting sub-components, which may also be spatially distributed. Regardless of the grammatical gender of a particular term, persons of male, female, or other gender identities are included.

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