Rotatable X-ray tube

Description

[0001] The invention relates to an X-ray source with a rotatable X-ray tube, an X-ray device, a method for controlling an X-ray source and an associated computer program product.

[0002] Imaging in a medical environment and / or for materials testing typically requires high rotational speeds, particularly a high rotational speed of an anode relative to an electron emitter. Due to the high rotational speeds, a conventional mechanically mounted X-ray tube, particularly a conventional mechanically mounted anode, is maintenance-intensive, as the mechanical bearing is typically subjected to heavy loads. Typically, the higher the rotational speed, the greater the load on the mechanical bearing. This load is usually caused by heat generation due to friction, lack of lubrication, and / or centrifugal force. The mechanical bearing can, for example, comprise a ball and / or a plain bearing.

[0003] Traditionally, the rotational speed is in the range of 50 to 200 Hz. Due to increasing demands in imaging, the power density on the anode should preferably increase, for example, through an increased electron current and / or a smaller focal spot. These requirements would lead to an increased lifting temperature on the anode. However, the maximum lifting temperature on the anode is limited by the respective anode material. The lifting temperature is typically the temperature difference between the maximum temperature in a focal spot and the temperature of an annular focal track, which temperature the focal track has, in particular, immediately before the electrons arrive at the focal spot.

[0004] It is known that higher speeds can be achieved by using magnetic bearings as a replacement for mechanical bearings.

[0005] EP 0 201 406 A1 describes an X-ray tube device comprising a shell containing the X-ray tube, the X-ray tube comprising a rotating anode mechanically coupled to a rotor driven by a driving stator, the rotor being arranged along a longitudinal axis and its suspension being provided by the magnetic bearings.

[0006] A comparable basic structure is also disclosed in WO 2010 / 136 325 A2, US 6,327,340 B1, US 6,198,803 B1, US 2017 / 0 148 606 A1 and DE 3 615 148 A.

[0007] From DE 696 18 283 T2, an X-ray source is known comprising: (a) a housing forming a vacuum enclosure, the entirety of the housing being rotatable about an axis, a part of the housing being an anode; (b) means for rotating the housing about the axis; (c) cathode means mounted within the housing for generating electrons and focusing the electrons onto an anode region remote from the axis; and (d) magnetic field means for holding the cathode within the housing, wherein the magnetic field means comprises a combination of active magnetic feedback and passive magnetic feedback using magnetic fields for restricting cathode movement in at least two angular or rectilinear directions, and wherein the cathode holding means comprises a magnetic field means as the sole means for holding the cathode within the rotatable vacuum enclosure.

[0008] Such an X-ray tube, which comprises a vacuum envelope, an anode which is formed at least along an annular surface within the envelope, a cathode assembly which is rotatably mounted in the envelope so as to enable relative rotational movement between the envelope and the cathode assembly, a capacitive coupling device which transmits an electrical alternating current energy from outside the envelope to the interior of the envelope, wherein the capacitive coupling device is connected to the cathode assembly, is described in DE 692 21 280 T2.

[0009] Due to the high heat generation, cooling requirements are typically correspondingly high. Other technical fields, for example, use of convective cooling, film cooling, and / or impingement cooling is known (see DE 10 2017 / 208 680 A1).

[0010] The invention is based on the object of specifying an X-ray tube with a rotatable X-ray tube, an X-ray device, a method for controlling an X-ray tube and an associated computer program product with a higher speed.

[0011] The problem is solved by the features of the independent claims. Advantageous embodiments are described in the subclaims.

[0012] A rotatable X-ray tube has an X-ray emission device with an anode for generating X-rays by means of incident electrons and a vacuum housing with an X-ray exit window for the X-rays to exit from the vacuum, wherein a rotor of a magnetic bearing is arranged in a rotationally fixed manner on an outer side or an inner side of the vacuum housing for contactless mounting of the rotatable X-ray tube within an X-ray source, wherein a contactless power receiver is arranged in a rotationally fixed manner on the outside or the inside of the vacuum housing for contactlessly receiving electrical power from a contactless power transformer of the X-ray emitter, wherein the X-ray emitting device is arranged in a rotationally fixed manner on the inside of the vacuum housing, wherein a supply circuit is connected between the contactless power receiver and the X-ray emitting device, and wherein the supply circuit supplies the X-ray emitting device with the electrical power.

[0013] An X-ray source according to the invention has the rotatable X-ray tube, the stator of the magnetic bearing for contactless mounting of the rotatable X-ray tube within the X-ray tube and the contactless power transformer for contactless transmission of electrical power to the contactless power receiver of the rotatable X-ray tube.

[0014] Advantageously, the rotatable X-ray tube enables comparatively high rotational speeds, particularly due to the contactless power receiver. The rotational speeds are in particular higher than 50 Hz, preferably higher than 200 Hz, and particularly advantageously higher than 300 Hz or 500 Hz. A further advantage can be that the rotatable X-ray tube enables safe continuous operation of the anode, particularly because a maximum stroke temperature can be maintained through the rotation of the rotatable X-ray tube. Compared to a conventional X-ray tube with a magnetic bearing, heat generation is particularly reduced because the electrical power is transmitted without contact. Typically, wear on the rotatable X-ray tube is lower because the electrical power is transmitted without contact.Due to the rotationally fixed arrangement of the components of the rotatable X-ray tube on the inside or outside of the vacuum housing, the X-ray emission device, in particular, is free of an anode mounted rotatably relative to the vacuum housing. In other words, an additional mechanical rotary bearing within the vacuum housing is advantageously eliminated compared to a conventional rotating anode X-ray tube, preferably reducing the mechanical complexity of the rotatable X-ray tube. The magnetic bearing and / or the elimination of the additional mechanical rotary bearing and / or the contactless power receiver enable advantages in particular with regard to lubrication and / or the operating life of the rotatable X-ray tube, in particular because no mechanical friction occurs. In a particularly advantageous example, the rotatable X-ray tube is completely contactless during operation.Due to regulatory requirements, the rotating X-ray tube may be required to have a galvanic contact with the X-ray tube assembly for protective grounding of the rotating X-ray tube. Alternatively or additionally, the X-ray tube assembly may have a protective grounding connection.

[0015] A rotatable X-ray tube is an X-ray tube that rotates during operation. Typically, the X-ray tube does not rotate before or after operation. The rotatable X-ray tube can be used in particular for imaging, such as medical imaging, or for image-based material testing. The rotatable X-ray tube, in particular the X-ray emission device and the vacuum housing, typically rotates completely, for example, due to its non-rotatable arrangement.

[0016] The rotationally fixed arrangement enables, in particular, a rotational speed of the rotatable X-ray tube to be equal to a rotational speed of the X-ray emission device and / or to a rotational speed of the vacuum housing and / or to a rotational speed of the rotor of the magnetic bearing and / or to a rotational speed of the contactless power receiver and / or to a rotational speed of the anode. The rotationally fixed arrangement typically corresponds to a mechanical fixation. The rotationally fixed arrangement can be implemented, for example, by means of a screw, a bayonet lock, a solder joint, a weld seam, and / or an adhesive. It is conceivable for the rotatable X-ray tube to have multiple rotationally fixed arrangements that are designed differently, for example, a combination of the screw, the bayonet lock, the solder joint, the weld seam, and / or the adhesive.

[0017] The rotatable X-ray tube, in particular the vacuum housing, is preferably rotationally symmetrical. The rotatable X-ray tube can be cylindrical and / or conical, at least in sections. The rotatable X-ray tube can, in particular, have a diameter that varies along a rotation axis.

[0018] The rotatable X-ray tube has the rotor of the magnetic bearing. The rotatable X-ray tube can be designed as the rotor of the magnetic bearing. Contactless bearing support typically occurs during operation of the rotatable X-ray tube. While the rotatable X-ray tube rotates, the rotatable X-ray tube preferably hovers above the stator of the magnetic bearing. Before or after operation, the rotatable X-ray tube can rest in contact, for example, in a retaining bearing of the X-ray tube. The rotor of the magnetic bearing is typically arranged in a ring-shaped manner on the vacuum housing in a rotationally fixed manner. The magnetic bearing is typically an active magnetic bearing. The rotatable X-ray tube is typically mounted within the X-ray tube by means of the magnetic bearing. It is fundamentally conceivable for the rotatable X-ray tube to be mounted on a base plate of the X-ray tube by means of the magnetic bearing.

[0019] The X-ray emitting device has the anode. The X-ray emitting device typically consumes at least some of the electrical power to generate the X-rays. Emitted electrons at least partially impact the anode, generating the X-rays. While the rotatable X-ray tube rotates, the X-ray emitting device preferably emits the X-rays. The X-ray emitting device is preferably designed such that the X-rays impinge essentially stationary outside the vacuum housing despite the rotation during operation of the rotatable X-ray tube. In this case, the anode typically has an annular focal path with a focal spot that varies over time and space. The electrons typically impinge on the focal spot, generating the X-rays.

[0020] The anode is typically rotationally symmetrical and / or comprises tungsten, gold, and / or molybdenum. The anode can generally be connected to a heat sink. The heat sink can, for example, be formed as part of the vacuum housing. In particular, the heat sink can be part of the exterior of the vacuum housing. The heat sink can, for example, form a rear side of the anode, while the electrons impinge on a front side of the anode. The heat sink can, for example, be cooled by heat exchange on a surface of the heat sink due to the rotation of the rotatable X-ray tube. The heat sink can preferably cool the anode passively or actively, for example by means of a circulating cooling medium.

[0021] If the rotor of the magnetic bearing is arranged in a rotationally fixed manner on the outside of the vacuum housing, the rotor of the magnetic bearing is typically arranged in a rotationally fixed manner outside the vacuum housing. It is generally preferred if the rotor and / or the contactless power receiver are arranged on the outside of the vacuum housing. If the X-ray emission device is arranged in a rotationally fixed manner on the inside of the vacuum housing, the X-ray emission device is typically arranged in a rotationally fixed manner inside the vacuum housing. The vacuum is typically within the vacuum housing. The vacuum housing is typically evacuated and / or vacuum-tight. The vacuum is in particular a high vacuum. The X-ray emission device is at least partially in the vacuum. The vacuum housing typically comprises glass and / or metal and / or plastic. The X-ray exit window is typically integrated into the vacuum housing.The X-ray exit window can, in particular, be annular. The vacuum housing has the X-ray exit window. The metal and / or the plastic of the vacuum housing is preferably X-ray-opaque. The X-ray exit window is advantageously X-ray transparent and / or comprises glass. The vacuum housing is preferably heat-resistant. The vacuum housing can have at least one electrical contact between the outer and inner surfaces so that the supply circuit can supply the X-ray emission device with electrical power. The vacuum housing can have an inerting system, for example, according to DE 10 2008 032 995 A1.

[0022] The contactless power receiver and the contactless power transmitter together form a contactless power transmission system. The contactless power receiver receives the electrical power. The electrical power is preferably transmitted using electromagnetic fields. In principle, it is conceivable that, depending on an operating mode, the contactless power receiver and the contactless power transmitter can transmit the electrical power bidirectionally. The contactless power receiver and the contactless power transmitter each transmit or receive the electrical power. According to one embodiment, the contactless power receiver is an inductive or capacitive power receiver. In this case, the contactless power transmission system is typically an inductive contactless power transmission system or a capacitive contactless power transmission system.The contactless power receiver and / or the contactless power transmitter can, in particular, be arranged in a ring around the rotation axis of the rotatable X-ray tube. In principle, it is conceivable for the contactless power receiver and / or the contactless power transmitter to be arranged in a rotationally fixed manner on one end face of the vacuum housing.

[0023] One embodiment provides that an electron emitter of the X-ray emission device has an emission surface arranged centrally on a rotation axis of the X-ray tube. Alternatively or additionally, the electron emitter of the X-ray emission device has an emission surface arranged annularly around the rotation axis of the X-ray tube. The electron emitter can, in particular, be a thermionic emitter, for example, according to DE 10 2010 020 151 A1, and / or a field-effect emitter comprising carbon and / or silicon.

[0024] One embodiment provides that the supply circuit supplies at least one of the following electrical consumers of the X-ray emission device with the electrical power: an electron emitter heater for heating an electron emitter, the electron emitter for emitting electrons, an electron barrier grid for blocking the emitted electrons, an electron deflector for deflecting the emitted electrons, an electron accelerating device for accelerating the emitted electrons between the electron emitter and the anode.

[0025] The electron emitter heating device is typically connected upstream of the electron emitter and, in particular, enables heating of the electron emitter to such an extent that electrons are emitted. Heating of the electron emitter can be achieved by bombarding the electron emitter with electrons emitted by the electron emitter heating device.

[0026] The electron emitter can emit electrons thermionically, for example, using electrical power. Alternatively, a gate voltage can be generated for the electron emitter using electrical power, especially if the electron emitter is a field-effect emitter.

[0027] The electrical power can preferably be used to switch on the electron barrier grid between the electron emitter and the anode in such a way that the electrons are discharged at the electron barrier grid and at least partially do not impinge on the anode.

[0028] The electron deflection device can be an inductive or capacitive electron deflection device that consumes electrical power to deflect the emitted electrons. Deflecting the emitted electrons can involve focusing.

[0029] The electron acceleration device preferably applies an acceleration voltage between the electron emitter and the anode using electrical power, thereby accelerating the electrons toward the anode. The acceleration voltage is typically less than 200 kV and / or greater than 10 kV, preferably between 50 and 140 kV.

[0030] One embodiment provides that the supply circuit supplies the rotor of the magnetic bearing with electrical power. This embodiment is particularly advantageous because the rotor of the magnetic bearing is also supplied with electrical power in a contactless manner.

[0031] Depending on which and how many electrical consumers the supply circuit supplies with electrical power, the supply circuit can have a parallel or series connection. The supply of electrical power can include forwarding the electrical power. In the simplest example, the supply circuit connects the contactless power receiver to the X-ray emission device, preferably with low resistance. The supply circuit is in particular an electrical intermediate circuit. It is conceivable that the supply circuit has a disconnect switch for electrically isolating the contactless power receiver from the X-ray emission device. The supply circuit can in particular have a fuse. The supply circuit can be electrically connected to the vacuum housing as a ground connection.

[0032] One embodiment provides that the supply circuit includes a rectifier. This embodiment is particularly advantageous when the electrical load requires direct current and the electrical power is applied to the contactless power receiver as alternating current. The rectifier can, in particular, be a full-bridge or half-bridge rectifier.

[0033] One embodiment provides that the supply circuit comprises a transformer. The transformer can be designed, in particular, as a high-voltage generator. The high-voltage generator can, for example, provide the acceleration voltage. Alternatively or additionally, the supply circuit can comprise a further transformer, which is designed, for example, as an isolation transformer for electrically isolating the X-ray emission device.

[0034] One embodiment provides that the rotatable X-ray tube further comprises a contactless control signal receiver for controlling the X-ray emission device, wherein the contactless control signal receiver is rotationally fixedly connected to the vacuum housing. The contactless control signal receiver can be arranged rotationally fixedly, in particular, on an inner or outer side of the vacuum housing.

[0035] Typically, the X-ray tube device has a contactless control signal transmitter for contactlessly transmitting control signals for controlling the X-ray emission device. The contactless control signal receiver and the contactless control signal transmitter typically form a contactless control signal transmission system. The contactless control signal transmission system is typically designed according to a contactless, in particular Bluetooth, wireless LAN, and / or mobile radio standard for transmitting the control signals.

[0036] The stator of the magnetic bearing can preferably support the rotor of the magnetic bearing, for example, drive it, in particular, set it in rotation. The X-ray tube can alternatively or additionally comprise a contactless electric motor for driving the rotor. The stator of the magnetic bearing, in particular, enables the rotor to levitate relative to the stator. The rotatable X-ray tube typically rotates relative to the stator. Typically, the stator and / or the contactless power transformer are stationary.

[0037] The X-ray tube can further comprise a cooling medium outside the rotatable X-ray tube for cooling the X-ray tube. The cooling medium can comprise a gas and / or a liquid. The rotatable X-ray tube and / or the X-ray tube can be cooled by means of the cooling medium, preferably by convection cooling or impingement cooling. The vacuum housing can comprise a cooling fin, a cooling plate, and / or a cooling fin, which are preferably in contact with the heat sink of the anode. The vacuum housing can, in particular, comprise a metal with high heat storage capacity and / or a phase-change storage device, in particular as an intermediate thermal energy storage device.

[0038] An X-ray device according to the invention comprises the X-ray source and an X-ray detector. The X-ray detector typically detects attenuation profiles generated by the X-rays. Using the attenuation profiles, a reconstruction unit can, for example, provide an image, particularly a medical image. The X-ray device can be, for example, a conventional X-ray device, a C-arm X-ray device, and / or a computed tomography X-ray device.

[0039] It is conceivable that the X-ray tube further comprises a control device for controlling the magnetic bearing and the contactless power transformer such that the magnetic bearing, in particular the rotor and / or the stator, and the contactless power transformer are coordinated with one another. The coordination particularly comprises controlling the magnetic bearing and the contactless power transformer such that an operating parameter of the magnetic bearing and an operating parameter of the contactless power transformer are interdependent. The control device is part of the computing unit. This embodiment is particularly advantageous because the electromagnetic fields of the magnetic bearing and / or the electromagnetic fields of the contactless power transformer typically interact. This interaction can lead to destabilization of the rotatable X-ray tube during operation.The interaction can comprise amplifying and / or canceling the respective electromagnetic fields. The control device advantageously compensates for the interaction by tuning. In other words, the control device preferably compensates for the interaction of the electromagnetic fields. This preferably allows the X-ray tube to be operated particularly stably.

[0040] The control device enables, in particular, carrying out a method according to the invention for controlling an X-ray source with the following steps: Receiving an actual value of an operating parameter of the magnetic bearing in the control device of the X-ray tube, receiving an actual value of an operating parameter of the contactless power transformer in the control device, setting a target value of the operating parameter of the magnetic bearing and / or a target value of the operating parameter of the contactless power transmission by means of the control device depending on the received actual value of the operating parameter of the magnetic bearing and the received actual value of the operating parameter of the contactless power transformer, whereby the X-ray tube is controlled, in particular coordinated with one another.

[0041] The actual value can, in particular, be a previously set target value or an actual value measured during operation. The operating parameter can, for example, be a current, a voltage, a speed, and / or a magnitude of electrical power. The operating parameter typically influences the respective electromagnetic field.

[0042] Receiving the actual value may include reading an applied actual value and / or measuring the actual value. The actual value may preferably be retrieved from a storage unit.

[0043] Setting the target value can include transmitting the target value to the magnetic bearing and / or the contactless power transmitter. It is generally conceivable that the target value is alternatively or additionally transmitted to the contactless power receiver, for example, using the control signals. Setting can include determining the target value of the operating parameter of the magnetic bearing and / or the target value of the operating parameter of the contactless power transmitter. The determination can be performed using an algorithm that incorporates the received actual value of the operating parameter of the magnetic bearing and the received actual value of the operating parameter of the contactless power transmitter. The algorithm can be adapted according to a model of the electromagnetic fields.

[0044] A computer program product according to the invention, which can be loaded directly into a memory of a computing unit, has program code means for executing a method for controlling an X-ray source when the computer program product is executed in the computing unit.

[0045] The computer program product can be a computer program or comprise a computer program. The computer program product has the program code means that map the method steps according to the invention. This allows the method according to the invention to be carried out in a defined and repeatable manner, and control over the forwarding of the method according to the invention can be exercised. The computer program product is configured such that the computing unit can carry out the method steps according to the invention using the computer program product. The program code means can be loaded into a memory of the computing unit and typically executed by a processor of the computing unit with access to the memory. If the computer program product, in particular the program code means, is executed in the computing unit, all inventive embodiments of the described method can be carried out.The computer program product is, for example, stored on a physical, computer-readable medium and / or digitally stored as a data packet in a computer network. The computer program product can represent the physical, computer-readable medium and / or the data packet in the computer network. The invention can therefore also be based on the physical, computer-readable medium and / or the data packet in the computer network. The physical, computer-readable medium can usually be connected directly to the computing unit, for example by inserting the physical, computer-readable medium into a DVD drive or plugging it into a USB port, as a result of which the computing unit can access the physical, computer-readable medium, in particular for reading purposes. The data packet can preferably be retrieved from the computer network. The computer network can have the computing unit or can be connected to the computing unit by means of a wide area network (WAN) ora (wireless) local area network connection (WLAN or LAN) to the computing unit. For example, the computer program product can be stored digitally on a cloud server at a storage location of the computer network, transferred to the computing unit via the WAN over the Internet and / or via the WLAN or LAN, in particular by accessing a download link that points to the storage location of the computer program product.

[0046] Features, advantages, or alternative embodiments mentioned in the description of the device are also applicable to the method, and vice versa. In other words, claims to the method can be developed with features of the device, and vice versa. In particular, the device according to the invention is used in the method.

[0047] The invention is described and explained in more detail below with reference to the exemplary embodiments illustrated in the figures. In the following description of the figures, essentially identical structures and units are designated by the same reference numerals as when the respective structure or unit first appeared.

[0048] They show: Fig. 1 a rotatable X-ray tube 10, Fig. 2 a rotatable X-ray tube 10 in a block diagram, Fig. 3 an alternative design of the rotatable X-ray tube 10, Fig. 4 an X-ray tube 20, Fig. 5 an X-ray device 30 and Fig. 6 a method for controlling an X-ray tube 20.

[0049] Fig. 1 shows a rotatable X-ray tube 10 in a cross-section along a rotation axis. The rotatable X-ray tube 10 has an X-ray emitting device 11 and a vacuum housing 13. The X-ray emitting device 11 has an anode 12 for generating X-rays by means of impinging electrons. The vacuum housing 13 has an X-ray exit window 14 for the X-rays to exit from the vacuum. The X-ray exit window 14 is annular in this embodiment.

[0050] A rotor 15 of a magnetic bearing is arranged in a rotationally fixed manner on an outer side of the vacuum housing 13 for contactless mounting of the rotatable X-ray tube 10 within an X-ray tube 20. Alternatively, the rotor 15 can be arranged in a rotationally fixed manner on an inner side of the vacuum housing 13. In this embodiment, the rotor 15 is annular. In this embodiment, the rotor 15 is mounted on the vacuum housing 13. Alternatively, the vacuum housing can have a groove for receiving the rotor 15.

[0051] On the outside of the vacuum housing 13, a contactless power receiver 16 is arranged in a rotationally fixed manner for contactless reception of an electrical power from a non- Fig. 1 The contactless power transmitter 17 of the X-ray tube 20 shown in FIG. Alternatively, the contactless power receiver 16 can be arranged in a rotationally fixed manner on an inner side of the vacuum housing 13. The contactless power receiver 16 is annular in this embodiment. The contactless power receiver 16 is typically an inductive or capacitive power receiver. In this embodiment, the contactless power receiver 16 is inserted into a further groove of the vacuum housing 13. Alternatively, the contactless power receiver 16 can be placed on the vacuum housing 13.

[0052] The X-ray emission device 11 is arranged in a rotationally fixed manner on the inside of the vacuum housing 13. In this exemplary embodiment, an electron emitter of the X-ray emission device 11 has an emission surface 19 arranged centrally on the rotation axis of the X-ray tube 10. The vacuum of the vacuum housing 13 is located in particular between the emission surface 19 of the X-ray emission device 11 and the anode 12.

[0053] A supply circuit 18 is connected between the contactless power receiver 16 and the X-ray emitting device 11, as well as the rotor 15, to supply electrical power. The supply circuit 18 supplies the X-ray emitting device 11 with electrical power. Fig. 1 shows that the supply circuit 18 contacts the anode 12 at the back. Not shown in Fig. 1 is a possible electrical connection between the supply circuit 18 and the emission surface 19.

[0054] The rotatable X-ray tube 10 cannot Fig. 1 shown contactless control signal receiver for controlling the X-ray emission device 11, wherein the contactless control signal receiver is connected to the vacuum housing 13 in a rotationally fixed manner.

[0055] Fig. 2 shows the rotatable X-ray tube 10 in a block diagram. The supply circuit 18 is connected between the contactless power receiver 16 and the X-ray emitting device 11. The supply circuit 18 supplies the electrical power from the contactless power receiver 16 to the X-ray emitting device 11.

[0056] The contactless power receiver 16, the supply circuit 18 and the X-ray emitting device 11 preferably form a closed circuit.

[0057] The supply circuit 18 preferably supplies at least one of the following electrical consumers of the X-ray emission device 11 with the electrical power: an electron emitter heater for heating an electron emitter, the electron emitter for emitting electrons, an electron barrier grid for blocking the emitted electrons, an electron deflector for deflecting the emitted electrons, an electron accelerating device for accelerating the emitted electrons between the electron emitter and the anode 12.

[0058] The supply circuit 18 may comprise a rectifier and / or a transformer.

[0059] Alternatively or additionally, the supply circuit 18 can supply the Fig. 2 supply the electrical power to the rotor 15 of the magnetic bearing shown.

[0060] Fig. 3 shows a Fig. 1 alternative embodiment of the X-ray tube 10. In this embodiment, an electron emitter of the X-ray emission device 11 has an emission surface 19 arranged in a ring around a rotation axis of the X-ray tube 10, instead of the Fig. 1 shown embodiment, wherein an electron emitter of the X-ray emission device 11 has an emission surface 19 arranged centrally on the rotation axis of the X-ray tube 10.

[0061] Fig. 4 shows an X-ray source 20 in a cross section along the rotation axis with the rotatable X-ray tube of Fig. 1 .

[0062] The X-ray source 20 comprises the rotatable X-ray tube 10, a stator 21 of a magnetic bearing for contactless mounting of the rotatable X-ray tube 10 within the X-ray source 20, and a contactless power transmitter 17 for contactless transmission of electrical power to the contactless power receiver 16 of the rotatable X-ray tube 10.

[0063] In this embodiment, the X-ray tube 20 has a control device 22 for controlling the magnetic bearing and the contactless power transformer 17 such that the magnetic bearing and the contactless power transformer 17 are coordinated with one another. For this purpose, the magnetic bearing and the contactless power transformer 17 are connected to the control device. Fig. 4 an X-ray exit window of the X-ray source 20 is arranged depending on the X-ray exit window 14, but not shown.

[0064] Fig. 5 shows an X-ray device 30. The X-ray device 30 has an X-ray source 20 and an X-ray detector 31. Between the X-ray source 20 and the X-ray detector 31, a patient P is positioned on a patient couch 32 for X-raying the patient P.

[0065] Fig. 6 shows a method for controlling an X-ray source 20 in a flow chart.

[0066] Method step S100 denotes receiving an actual value of an operating parameter of the magnetic bearing in a control device 22 of an X-ray tube 20.

[0067] Method step S101 denotes receiving an actual value of an operating parameter of the contactless power transformer 17 in the control device 22.

[0068] Method step S102 denotes setting of a target value of the operating parameter of the magnetic bearing and / or a target value of the operating parameter of the contactless power transmitter 17 by means of the control device 22 as a function of the received actual value of the operating parameter of the magnetic bearing and the received actual value of the operating parameter of the contactless power transmitter 17, whereby the X-ray tube 20 is controlled.

[0069] Although the invention has been illustrated and described in detail by the preferred embodiments, the invention is nevertheless not limited by the disclosed examples and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims

1. X-ray emitter (20), having a rotatable x-ray tube (10), wherein the rotatable x-ray tube (10) - has an x-ray beam emission apparatus (11) with an anode (12) for a generation of x-ray beams by means of impacting electrons and - a vacuum housing (13) with an x-ray beam exit window (14) for an escape of x-ray beams from the vacuum, wherein a rotor (15) of a magnetic bearing is arranged in a torque-proof manner on an exterior or an interior of the vacuum housing (13) for a contactless support of the rotatable x-ray tube (10) within the x-ray emitter (20), wherein a contactless power receiver (16) is arranged in a torque-proof manner on the exterior or the interior of the vacuum housing (13) for a contactless receiving of an electrical power from a contactless power transmitter (17) of the x-ray emitter (20), wherein the x-ray beam emission apparatus (11) is arranged in a torque-proof manner on the interior of the vacuum housing (13), wherein a supply circuit (18) is connected between the contactless power receiver (16) and the x-ray beam emission apparatus (11) and wherein the supply circuit (18) supplies the x-ray beam emission apparatus (11) with the electrical power, wherein the x-ray emitter (20) further - has a stator (21) of the magnetic bearing for a contactless support of the rotatable x-ray tube (10) within the x-ray emitter (20) and - the contactless power transmitter (17) for the contactless transmission of the electrical power to the contactless power receiver (16) of the rotatable x-ray tube (10).

2. X-ray emitter (20) according to claim 1, wherein the supply circuit (18) supplies at least one of the following electrical consumers of the x-ray beam emission apparatus (11) with the electrical power: - an electron emitter heating apparatus for heating an electron emitter, - the electron emitter for emitting electrons, - an electron barrier grid for blocking the emitted electrons, - an electron deflection apparatus for deflecting the emitted electrons, - an electron acceleration apparatus for accelerating the emitted electrons between the electron emitter and the anode (12).

3. X-ray emitter (20) according to one of the preceding claims, wherein the supply circuit (18) supplies the rotor (15) of the magnetic bearing with the electrical power.

4. X-ray emitter (20) according to one of the preceding claims, wherein the supply circuit (18) has a rectifier.

5. X-ray emitter (20) according to one of the preceding claims, wherein the supply circuit (18) has a transformer.

6. X-ray emitter (20) according to one of the preceding claims, wherein the x-ray beam exit window (14) is ring-shaped.

7. X-ray emitter (20) according to one of the preceding claims, further having - a contactless control signal receiver for controlling the x-ray beam emission apparatus (11), wherein the contactless control signal receiver is connected to the vacuum housing (13) in a torque-proof manner.

8. X-ray emitter (20) according to one of the preceding claims, wherein the contactless power receiver is an inductive or capacitive power receiver.

9. X-ray emitter (20) according to one of the preceding claims, wherein an electron emitter of the x-ray beam emission apparatus (11) has an emission surface (19) arranged centrally on an axis of rotation of the x-ray tube (10).

10. X-ray emitter (20) according to one of the preceding claims, wherein an electron emitter of the x-ray beam emission apparatus (11) has an emission surface (19) arranged in a ring-shaped manner around an axis of rotation of the x-ray tube (10).

11. Method for controlling an x-ray emitter (20) according to one of the preceding claims, comprising the following steps: - receiving an actual value of an operating parameter of the magnetic bearing in a control apparatus (22) of the x-ray emitter (20), - receiving an actual value of an operating parameter of the contactless power transmitter (17) in the control apparatus (22), - adjusting a target value of the operating parameter of the magnetic bearing and / or a target value of the operating parameter of the contactless power transmitter (17) by means of the control apparatus (22) as a function of the received actual value of the operating parameter of the magnetic bearing and the received actual value of the operating parameter of the contactless power transmitter (17), as a result of which the x-ray emitter (20) is controlled.

12. Computer program product which can be loaded directly into a memory of a computing unit, having program code means, which cause the x-ray emitter according to one of claims 1 to 10 to execute the method steps according to claim 11, wherein the control apparatus is part of the computing unit, if the computer program product is executed in the computing unit.

13. X-ray facility (30) having - an x-ray emitter (20) according to one of claims 1 to 10 and - an x-ray detector (31).