Device for measuring emission current of x-ray tube

Abstract

The invention relates to a device for determining the emission current of an X-ray tube (100), and to an X-ray tube and an X-ray system comprising such a device. The apparatus comprises: a sensor (110) configured for determining an emission current (107, 108) of the X-ray tube (100); and a first X-ray tube wire (111) and a second X-ray tube wire (112) configured for operating the X-ray tube (100). The sensor (110) is arranged at a first X-ray tube wire (111) and at a second X-ray tube wire (112) on the high voltage potential side of the X-ray tube. The sensor (110) is configured and arranged for measuring a resultant magnetic field generated by a magnetic field superimposed at the sensor (110). The apparatus is configured for determining an emission current (107, 108) of the X-ray tube (100) based on the resultant magnetic field. The invention also relates to the use of a Hall sensor for measuring the emission current of an X-ray tube.

Description

Technical Field

[0001] The present invention relates to the field of X-ray tubes, in particular to the field of emission current sensing of X-ray tubes. In addition, the present invention relates to detecting the emission current of the high voltage potential side of the X-ray tube. More specifically, the present invention relates to a device for detecting the emission current of an X-ray tube, an X-ray tube comprising such a device, an X-ray system comprising such a device, a method for detecting the emission current of an X-ray tube, and the use of a Hall sensor for detecting the emission current of an X-ray tube. Background Art

[0002] In practice, the emission current of each X-ray tube depends on the heating current and the pick-up voltage in a different way, also for tubes of the same type. For example, after a long operation of an X-ray tube, it may happen that some parts of the surface of the heating filament are evaporated, so that the heating filament becomes thinner. Then, the same value of the heating current may lead to a larger emission current than before the parts of the surface of the heating filament were evaporated. This may lead to a relatively large deviation of the current through the X-ray tube from the acquisition current value desired at the start of the acquisition.

[0003] Typically, the temperature of the filament of an X-ray tube (ie, the heating current through the filament) is controlled in order to regulate the emission current, ie, the emission current from the filament to the anode target.

[0004] X-ray tube based emission current measurements are an essential characteristic of the functionality of an X-ray tube. For example, filament failure due to tungsten wear (which can be the primary failure mode for some X-ray tubes) can be predicted from the heating current required to achieve a given emission current.

[0005] To ensure patient safety (e.g. with regard to X-ray dose), to avoid tube overload (that means to avoid excessive temperatures on the anode), to comply with regulatory aspects, to enable dose modulation and to enable tube temperature monitoring, the emission current of the X-ray tube needs to be regulated.

[0006] Measuring the emission current may therefore be an improved feature for X-ray tube monitoring.Therefore, there is a need for direct, fast and accurate measurement of the emission current, and for fast and accurate regulation of the emission current of an X-ray tube. Summary of the invention

[0007] There is a need for an improved measurement process of the emission current, which in turn would lead to improved patient safety (e.g. in terms of X-ray dose), for monitoring tube overload (which means avoiding excessive temperatures on the anode), for regulatory compliance, for enabling dose modulation and for improved tube temperature supervision.

[0008] The inventors of the present invention have observed that measurement of the emission current on the high voltage potential side of an X-ray tube allows for a fast, direct emission current measurement without having to derive the emission current from other X-ray tube measurements (eg from the heating current).

[0009] It is an object of the present invention to provide an emission current measurement of an X-ray tube, wherein the emission current can be measured quickly and directly.

[0010] The invention is defined by the independent claims, wherein further embodiments are defined by the dependent claims.

[0011] According to a first aspect of the present invention, a device for determining an emission current of an X-ray tube includes a sensor configured to determine the emission current of the X-ray tube, and includes a first X-ray tube wire and a second X-ray tube wire configured to operate the X-ray tube. The sensor is arranged at the first X-ray tube wire and the second X-ray tube wire, wherein the sensor is arranged at the high voltage potential side of the X-ray tube. In addition, the sensor is configured and arranged at the first X-ray tube wire and the second X-ray tube wire in such a way that a first magnetic field generated by a heating current of the X-ray tube in the first X-ray tube wire, a second magnetic field generated by an emission current of the X-ray tube in the first X-ray tube wire, a third magnetic field generated by a heating current of the X-ray tube in the second X-ray tube wire, and a fourth magnetic field generated by an emission current of the X-ray tube in the second X-ray tube wire are superimposed at the sensor. The sensor is configured to measure a composite magnetic field generated by the magnetic fields superimposed at the sensor. The device is configured to determine the emission current of the X-ray tube based on the composite magnetic field.

[0012] In the context of the present invention, the term "X-ray tube leads" should be understood to describe leads for operating an X-ray tube, wherein the X-ray tube leads are configured for providing a connection to a power supply of the X-ray tube.

[0013] In the context of the present invention, the term "high voltage potential side" is to be understood as describing a voltage side of the X-ray tube which has a different potential than the ground potential side, e.g. a higher potential. Components for operating the X-ray tube, e.g. a generator, are connected to ground potential, and the power generated by the generator for operating the X-ray tube generates a higher voltage potential, referred to as the high voltage potential side. The determination of the emission current must be performed at a high voltage potential (e.g. up to 150 kV is required for X-ray tube operation), whereas the measurement results are required and provided to the components at ground potential. Therefore, standard external probes cannot be used. Devices, components and / or elements designed for the ground potential side cannot be operated on the high voltage potential side. Therefore, special requirements are placed on devices, components, etc. in order to be able to operate on the high voltage side.

[0014] In the context of the present invention, the term "resulting magnetic field" should be understood to describe a magnetic field that may consist of a superposition of more than one magnetic field. For example, the resulting magnetic field may be a main magnetic field that includes or contains a superimposed first magnetic field, a second magnetic field, a third magnetic field, and a fourth magnetic field, or a portion thereof. It may include a reduced magnetic field of the first magnetic field and the third magnetic field and a non-reduced second magnetic field and the fourth magnetic field.

[0015] In this embodiment, a first X-ray tube wire and a second X-ray tube wire are configured to provide a connection between a generator configured to drive an X-ray tube and a cathode of the X-ray tube. The cathode may include a filament, so the wire may provide a connection between the generator and the filament of the X-ray tube. Specifically, one wire may be an input wire and the other wire may be an output wire. The sensor is arranged at the high voltage potential side of the X-ray tube, at the X-ray tube wire, which provides a current from the generator of the X-ray tube to the cathode of the X-ray tube, and vice versa, wherein the (X-ray tube) wire connecting the generator and the cathode of the X-ray tube is arranged in such a way that the magnetic field caused by the heating current in each wire is reduced. In other words, the X-ray tube wire entering the cathode, filament from the generator and exiting the cathode, filament should be oriented so that the magnetic field caused by the heating current is reduced or canceled. This reduction in the magnetic field is due to the specific arrangement of the sensor at the X-ray tube wire and the way the magnetic field is generated at the X-ray tube wire and the way the sensor detects the magnetic field. Depending on the selected sensor arrangement and / or sensor elements, the heating current through the X-ray tube wires may flow in the same direction or the heating current through the X-ray tube wires may flow in opposite directions. The superposition of the different magnetic fields results in the effect that the magnetic field associated with the heating current will be reduced or will be cancelled at the sensor, so that only the magnetic field of interest, i.e. the magnetic field of the emission current, remains measurable for the sensor. As described above, the net contribution of the heating current will be practically zero, while the magnetic field caused by the emission current will result in a measurable result.

[0016] Magnetic field compensation is used in order to distinguish between heating current and emission current, both of which flow on the high voltage potential side of the X-ray tube. Therefore, due to the specific arrangement of the sensor at the X-ray tube wire, the magnetic field of the heating current can be reduced or preferably offset by superposition of magnetic fields at the sensor. In particular, by superposition of the magnetic fields caused by the heating currents (i.e. the input heating current into the X-ray tube and the output heating current from the heating tube), this will be explained in the following figures. Since the heating current into the cathode, the filament is equal to the heating current from the cathode, the filament, the net magnetic field of the heating current is reduced or offset if the geometry of the arrangement of the device of the present embodiment is selected accordingly. The residual magnetic field of the emission current leads to a measurable signal on the sensor, which does not contain any residual heating current contribution or at least only contains some heating current residues, which can be filtered out at a later stage. Therefore, due to the reduction of the heating current magnetic field, the dynamic range requirements of the sensor can be reduced, which enables a clean emission current measurement. Therefore, the sensor measures the residual magnetic field of the emission current, which is related to the emission current flowing through the X-ray tube wire. In addition to determining the emission current, the sensor may be configured to generate an emission current signal, which may include the value of the determined emission current, and which may be provided to other components of the X-ray tube or other components of an embodiment of the present invention, as will be described below.

[0017] Determining the emission current on the high voltage potential side of the X-ray tube allows a direct and rapid determination of this current, so that external probes can be omitted and there is no need to derive the emission current from other measured values ​​(e.g. the heating current). Furthermore, it is advantageous that the high voltage potential side of the X-ray tube can be equipped with such a device, so that a direct and / or internal emission current measurement is possible.

[0018] The emission current may be in the range of 10 mA to 1500 mA, which may be covered by a larger heating current (e.g. up to 15 A during ramp-up). This would therefore require any sensor to have a large noise-free dynamic range. When using the apparatus described herein, the larger heating current may be reduced so that the sensor can measure the remaining emission current. The solution as described above may be completely autonomous. The limited power requirement may be met by using some of the power of the heating current source. Thus, the apparatus for determining the emission current may be located self-contained within the X-ray tube or within the high voltage generator arrangement driving the X-ray tube.

[0019] According to an exemplary embodiment of the present invention, the sensor is arranged relative to the first X-ray tube wire and the second X-ray tube wire so that the heating current flowing through the first X-ray tube wire flows in a current direction opposite to the heating current flowing through the second X-ray tube wire. In other words, the X-ray tube wires entering the cathode, the filament from the generator and exiting the cathode, the filament should be oriented so that the magnetic field caused by the heating current is reduced or cancelled. This reduction in the magnetic field results from the heating current flowing in the X-ray tube wire in the opposite current direction. The superposition of the different magnetic fields results in the effect that the magnetic field related to the heating current will be reduced or cancelled at the sensor, so that only the magnetic field of interest (i.e., the magnetic field of the emission current) is still measurable for the sensor. As described above, the net contribution of the heating current will be virtually zero, while the magnetic field caused by the emission current will result in a measurable result.

[0020] According to an exemplary embodiment of the present invention, the sensor is further configured to generate a voltage signal based on the measured composite magnetic field, wherein the device is configured to determine the emission current of the X-ray tube based on the generated voltage signal of the sensor. The generated voltage signal includes a common ratio with the measured magnetic field, so that the emission current can be determined using the generated voltage signal. The ratio between the voltage signal, the magnetic field and / or the emission current may depend on the characteristics of the selected sensor.

[0021] According to an exemplary embodiment of the present invention, the composite magnetic field is the sum of the second magnetic field generated at the sensor and the fourth magnetic field generated. In other words, the composite magnetic field is the sum of the residual magnetic field of the transmission current at the sensor. The composite magnetic field may depend on the arrangement position of the sensor. In addition, the composite magnetic field may include external magnetic fields, which are also superimposed at the sensor.

[0022] According to an exemplary embodiment of the invention, the sensor is arranged at a first X-ray tube conductor and at a second X-ray tube conductor inside the X-ray tube, or the sensor is arranged at a first X-ray tube conductor and at a second X-ray tube conductor on the high voltage potential side of the generator driving the X-ray tube. Thus, the sensor can be arranged on the high voltage potential side of the X-ray tube, both inside the X-ray tube and outside the X-ray tube, for example on the generator side, but still on the high voltage potential side. It is also possible to arrange, for example, two sensors, both of which are arranged on the high voltage potential side of the X-ray tube. One sensor can be arranged inside the X-ray tube and the other sensor can be arranged outside the X-ray tube, as described above. Thus, the device can include more than one sensor for measuring and determining the emission current of the X-ray tube. According to this embodiment, differences and changes in the emission current during operation of the X-ray tube can be determined quickly and directly at each single sensor and / or at two sensors.

[0023] According to an exemplary embodiment of the present invention, the device further comprises a substrate, wherein the sensor is arranged on the substrate, wherein the substrate is in particular a printed circuit board (PCB). An advantage of the magnetic field effect cancellation method is that it allows the arrangement of the sensor and the X-ray tube wires in a very compact size, which can be easily manufactured on the PCB. The X-ray tube wires can be arranged on and / or inside the PCB in order to correctly align with the sensor and ensure sufficient superposition of the magnetic field to be measured. The sensor-X-ray tube wire arrangement structure can be referred to as a planar sensor arrangement structure, because the X-ray tube wires are arranged on different planes from each other.

[0024] According to an exemplary embodiment of the invention, the device further comprises a housing surrounding the sensor and at least partially surrounding the first X-ray tube wire and the second X-ray tube wire, wherein the housing is configured for shielding the sensor from further magnetic fields. Furthermore, the housing may also surround a PCB on which the sensor may be located. Thus, the entire sensor arrangement, i.e. the device itself, is arranged inside the housing and may be shielded from external magnetic fields which may interfere with the sensor and / or may affect the measured magnetic field or the superposition of magnetic fields to be measured.

[0025] According to an exemplary embodiment of the present invention, at least two X-ray tube wires are arranged below the sensor, wherein the at least two X-ray tube wires are a first X-ray tube wire and a second X-ray tube wire arranged below the sensor.

[0026] The X-ray tube wires below the sensor may be arranged to overlap each other, thereby providing a stacked arrangement structure of the X-ray tube wires below the sensor and / or the X-ray tube wires below the sensor are arranged adjacent to each other in the same plane below the sensor. In other words, the X-ray tube wires transmitting opposite currents may be placed to overlap each other and / or the X-ray tube wires transmitting opposite currents may be placed adjacent to each other.

[0027] According to another exemplary embodiment, the first X-ray tube wire includes a plurality of sub-X-ray tube wires, and the second X-ray tube wire includes a plurality of sub-X-ray tube wires. These sub-wires may also be arranged below the sensor. In addition, the sub-wires may also be arranged in a stacked arrangement structure as described above. Specifically, the sensor may be configured and arranged at the sub-X-ray tube wire of the first X-ray tube wire and at the sub-X-ray tube wire of the second X-ray tube wire in such a manner that the magnetic field generated by the heating current of the X-ray tube in the sub-X-ray tube wire of the first X-ray tube wire, the magnetic field generated by the emission current of the X-ray tube in the sub-X-ray tube wire of the first X-ray tube wire, the magnetic field generated by the heating current of the X-ray tube in the sub-X-ray tube wire of the second X-ray tube wire, and the magnetic field generated by the emission current of the X-ray tube in the sub-X-ray tube wire of the second X-ray tube wire may be superimposed at the sensor.

[0028] In other words, the X-ray tube wires can be further subdivided into multiple individual smaller wires connected in parallel or in series (in order to amplify the magnetic field). For example: two X-ray tube wires transmit the input heating current I_in, and two X-ray tube wires transmit the output heating current I_out. The subdivided X-ray tube wires can then be oriented in various configurations (two currents I_in on the top layer, two I_out on the bottom layer, or I_in is located to the left of I_out on the top layer and I_out is located to the left of I_in on the bottom layer). There is a virtually infinite set of configurations. The X-ray tube wires can be distributed on one or more PCB layers. In addition, the X-ray tube wires can be surrounded by a potentially grounded copper layer on the top / bottom layer of the PCB.

[0029] According to an exemplary embodiment of the present invention, the device further comprises a magnetic core, wherein the sensor is arranged inside a gap of the magnetic core, wherein the magnetic core is in particular a toroidal magnetic core, wherein the first X-ray tube wire and the second X-ray tube wire extend through the magnetic core or are wound around the magnetic core. Specifically, the magnetic core can be a slotted toroidal magnetic core, wherein the sensor (i.e., the Hall sensor) can be arranged in the gap of the toroidal magnetic core. The X-ray tube wires transmitting the heating current and the emission current can be wound around the magnetic core (which can increase the magnetic field strength) or fed through the magnetic core. Due to appropriate cable connections, the heating currents (I_in and I_out) flowing through the wires from the inside and outside directions flow in opposite directions, and a field effect similar to a planar X-ray tube wire arrangement structure can occur.

[0030] According to an exemplary embodiment of the invention, the sensor comprises at least one Hall sensor for measuring a magnetic field.

[0031] One Hall sensor is sufficient to measure the magnetic field generated by the emission current and heating current flowing through the X-ray tube wires. When using the device according to an embodiment of the present invention, no active or passive components are required in the direct path of the arc discharge direction on the high voltage potential side of the X-ray tube and / or generator. The arc discharge direction is the direction in which the X-ray tube may have an arc, which means a very fast discharge event. If such an event can occur, a voltage discharge of about 150kV is performed within a few μs. These events make it impossible to use simple settings (such as shunt resistors) to measure the emission current, because these settings will be damaged by the corresponding arc events. Therefore, when using a Hall sensor, a short current pulse due to the arc (which can be ~1000A) will result in a short magnetic field pulse measured by the Hall sensor, but the Hall sensor itself will not be damaged.

[0032] According to an exemplary embodiment of the present invention, the sensor includes a first Hall sensor arranged at a first X-ray tube wire and a second Hall sensor arranged at a second X-ray tube wire. At the first Hall sensor, the first magnetic field and the second magnetic field can be superimposed, and at the second Hall sensor, the third magnetic field and the fourth magnetic field can be superimposed. The first Hall sensor can measure the first synthetic magnetic field, and the second Hall sensor can measure the second synthetic magnetic field, wherein the device can be configured to determine the emission current of the X-ray tube based on the first synthetic magnetic field and the second synthetic magnetic field. Instead of one Hall sensor, one Hall sensor can also be used for each X-ray tube wire, wherein the Hall sensor on each X-ray tube wire measures the magnetic field generated at the X-ray tube wire to which the sensor is attached. Therefore, it is not necessary to measure all four magnetic fields by one Hall sensor. The device can determine the emission current from the two Hall sensors. Specifically, the device can determine the emission current based on the first voltage signal generated by the first Hall sensor and the second voltage signal generated by the second Hall sensor. The Hall sensor or two Hall sensors can generate an analog output voltage and include a sufficiently high bandwidth so as to be able to measure the magnetic field generated by the emission current and the magnetic field generated by the heating current. By arranging a Hall sensor at each X-ray tube lead, external interference (eg, external magnetic field) acting on each corresponding X-ray tube lead can be individually reduced or eliminated.

[0033] According to another embodiment of the present invention, the apparatus may further include an amplifier configured to combine a first voltage signal from the first Hall sensor and a second voltage signal from the second Hall sensor. The amplifier may combine the two voltage signals into a composite voltage signal, from which an emission current (e.g., a value thereof) may be determined. Depending on the current flow direction of the heating current through the first X-ray tube wire and the second X-ray tube wire, the amplifier is configured to combine the first voltage and the second voltage by adding them or subtracting them from each other to determine the emission current.

[0034] Specifically, if the current flow direction in the first X-ray tube wire and the second X-ray tube wire may be different, the combination of the two voltage signals includes adding the two voltage values. On the other hand, if the current flow direction through the first X-ray tube wire and the second X-ray tube wire is the same, the combination of the two voltage signals may include subtracting the analog voltages, wherein the resultant differential voltage at the output of the amplifier is the emission current. In both cases, the device can determine the emission current based on the resultant voltage output from the amplifier. Afterwards, the signal can be further cleaned up by filtering and conditioning.

[0035] The first Hall sensor and the second Hall sensor can be arranged adjacent to each other, wherein they are arranged adjacent to each other so that the sensitivity to external fields can be reduced. Conversely, it is also possible to arrange the first Hall sensor located at the first X-ray tube lead and the second Hall sensor located at the second X-ray tube lead apart. The arrangement used for the two Hall sensors relative to each other can depend on the high voltage potential side of the X-ray tube and / or the available space in the X-ray tube.

[0036] The arrangement of the first Hall sensor and the second Hall sensor may be combined with any other embodiment of the invention described herein. For example, each of the two Hall sensors may be arranged at a corresponding X-ray tube wire, which may include further sub-wires as described above. Furthermore, when two Hall sensors are used, each of them may be arranged inside a gap of a (ring-shaped) magnetic core, wherein the first X-ray tube wire and the second X-ray tube wire extend through different magnetic cores (or are wound around different magnetic cores).

[0037] According to an exemplary embodiment of the present invention, the device further comprises a communication unit configured to send data at least containing the determined emission current to at least one of an X-ray system, a generator of an X-ray tube and an external analysis unit. The communication unit may also be configured to receive at least one of a measurement time for measuring the emission current at a specific moment, a reference value for the emission current and a target value for the emission current. The expression of at least one of a measurement time for measuring the emission current at a specific moment, a reference value for the emission current and a target value for the emission current means that the communication unit may receive at least one, two or all of them. Specifically, it means a measurement time for measuring the emission current at a specific moment, a reference value for the emission current and / or a target value for the emission current, and it is sufficient if, for example, only a reference value for the emission current is present.

[0038] The communication unit may also be configured to transmit at least one or both of the potential gate signal and / or the X-ray tube identification signal to any other external unit or component of the X-ray system and / or the X-ray tube, which means to at least one of them, or also to all of them.

[0039] According to an exemplary embodiment, the communication unit is a communication interface connected to ground potential, wherein communication with sensors located on the high voltage potential side of the X-ray tube may be performed via an optical connection (e.g., optical fiber), wireless communication, or other electronic components suitable for communication between different voltage potentials. For example, the communication unit may use a digital bus that is connected to the generator, which may be used to unlock the full potential power rating of multiple X-ray tube components, which may be used to avoid tube overload.

[0040] According to an exemplary embodiment of the present invention, the device further comprises at least one filter for filtering the residual heating current of the first X-ray tube wire and / or the residual heating current of the second X-ray tube wire. The filter may be an analog filter and / or a digital filter. Furthermore, the bandwidth of the filter may be about 1 kHz. More than one filter may also be used. For example, for each X-ray tube wire, a corresponding filter is used to filter the magnetic field contributions of the heating current, which are not reduced and / or offset after superposition at the sensor. Typically, the heating current is an alternating current of about 20 kHz to avoid electronic focusing artifacts, while the emission current is a first approximation direct current, and then an analog or digital filter may be used to limit the residual contribution from the heating current. The filter bandwidth should be about 1 kHz to provide sufficient time resolution for the heating current regulation.

[0041] According to an exemplary embodiment of the present invention, an X-ray tube may include a device for measuring an emission current on the X-ray tube according to any of the above embodiments. The X-ray tube is operated via a first X-ray tube lead and a second X-ray tube lead of the X-ray tube. Specifically, the device is arranged at a high voltage potential side of the X-ray tube inside or outside the X-ray tube.

[0042] An advantage may be that the device as described above can be used for predictive maintenance of X-ray tubes, whereby usage parameters and important parameters that are related to or derivable from the emission current can be observed. For example, filament failure due to tungsten wear (the main failure mode of some X-ray tubes) can be predicted based on the heating current required to reach a given emission current. Thus, the determination of the emission current can allow conclusions to be drawn about the state of the filament.

[0043] According to an exemplary embodiment of the present invention, an X-ray system comprises an X-ray tube, a generator configured to drive the X-ray tube, and a device for measuring an emission current of the X-ray tube according to any of the above embodiments. The X-ray tube is operated by the generator via a first X-ray tube lead and a second X-ray tube lead of the X-ray tube, wherein the device can be configured to communicate with the X-ray system using a communication unit of the device.

[0044] According to a second aspect of the present invention, a method for measuring an emission current of an X-ray tube is described. The method comprises the following steps: operating an X-ray tube using a first X-ray tube wire and a second X-ray tube wire, arranging sensors at the first X-ray tube wire and at the second X-ray tube wire, in particular so that a heating current flowing through the first X-ray tube wire and a heating current flowing through the second X-ray tube wire can be detected by the sensors. The step of arranging the sensors comprises positioning the sensors on the high voltage potential side of the X-ray tube. Furthermore, the method comprises the following steps: due to the configuration and arrangement structure of the sensors, a first magnetic field generated by the heating current of the X-ray tube in the first X-ray tube wire, a second magnetic field generated by the emission current of the X-ray tube in the first X-ray tube wire, a third magnetic field generated by the heating current of the X-ray tube in the second X-ray tube wire, and a fourth magnetic field generated by the emission current of the X-ray tube in the second X-ray tube wire are superimposed. Furthermore, the method comprises the following steps: measuring a composite magnetic field formed by the superimposed magnetic fields at the sensor by the sensor, and determining the emission current of the X-ray tube based on the composite magnetic field formed by the superimposed magnetic fields at the sensor.

[0045] The arranging step may further include arranging sensors at the first X-ray tube wire and the second X-ray tube wire so that a heating current flowing through the first X-ray tube wire flows in a current direction opposite to a heating current flowing through the second X-ray tube wire.

[0046] If the sensor may include at least two Hall sensors, i.e., the first and second Hall sensors as described in the above embodiment, the step of arranging the sensors may further include arranging the first Hall sensor at the first X-ray tube lead and arranging the second Hall sensor at the second X-ray tube lead. The step of determining the emission current may further include determining a voltage generated by the measured synthetic magnetic field. Specifically, when two Hall sensors are used, the determining step may further include determining a first voltage at the first Hall sensor and determining a second voltage at the second Hall sensor. Thereafter, the first voltage and the second voltage values ​​are combined, for example, by an amplifier as described in the above embodiment, wherein the synthetic voltage value is used to determine the emission current of the X-ray tube.

[0047] According to a third aspect of the invention, a use of a Hall sensor for measuring an emission current of an X-ray tube is described, wherein the measurement is performed by superimposing a magnetic field generated by a heating current of the X-ray tube in a first X-ray tube conductor, a magnetic field generated by an emission current of the X-ray tube in a first X-ray tube conductor, a magnetic field generated by a heating current of the X-ray tube in a second X-ray tube conductor, and a magnetic field generated by an emission current of the X-ray tube in a second X-ray tube conductor, and determining the emission current of the X-ray tube based on a synthetic magnetic field generated by the superimposed magnetic fields at the Hall sensor. When the Hall sensor is used, the device can operate autonomously on the high voltage potential side of the X-ray tube. In addition, as described above, the Hall sensor is not damaged by possible arcing events of the X-ray tube. Depending on the position of the Hall sensor at one X-ray tube conductor or multiple X-ray tube conductors, the magnetic values ​​of the first magnetic field, the second magnetic field, the third magnetic field, and the fourth magnetic field may be different from each other, wherein not all magnetic fields may be superimposed at the sensor. Therefore, the magnetic values ​​of some magnetic fields from the first magnetic field, the second magnetic field, the third magnetic field, and / or the fourth magnetic field may be almost zero.

[0048] When at least two Hall sensors are used, not all four magnetic fields may be superimposed equally at each Hall sensor. For example, a first Hall sensor is used at a first X-ray tube lead, where the first magnetic field and the second magnetic field are superimposed at the first Hall sensor. Conversely, a second Hall sensor may be used at a second X-ray tube lead, where the third magnetic field and the fourth magnetic field are superimposed at the second Hall sensor. Thus, the first Hall sensor may measure the first composite magnetic field, while the second Hall sensor may measure the second composite magnetic field.

[0049] According to a fourth aspect of the present invention, a computer program unit for measuring an emission current of an X-ray tube is described. When the computer program unit is executed by a processor of an apparatus for measuring an emission current of an X-ray tube, the computer program unit is adapted to cause the apparatus to measure the emission current of the X-ray tube through at least one sensor, receive data from the at least one sensor through a data processing unit and analyze the received data, thereby evaluating whether the measured emission current is at least one of a target emission current and a threshold emission current based on the analyzed data, and controlling the at least one sensor and / or the X-ray tube based on the determined emission current.

[0050] The threshold emission current may be a threshold value which should not be exceeded. The threshold value may be used for critical component temperatures of the X-ray tube, or for individual components of the X-ray tube, such as the cathode, the filament, etc. The computer program unit may control at least one sensor, wherein the sensor may be controlled in such a way that the computer program unit may set a measurement time, or may control a measurement interval or a filtering of the measured values.

[0051] The computer program element may further be adapted to cause the arrangement to measure the emission current of the X-ray tube by means of a sensor comprising at least two Hall sensors.

[0052] It must be noted that embodiments of the present invention have been described with reference to different subject matters. In particular, some embodiments have been described with reference to device type claims, while other embodiments have been described with reference to method type claims. However, a person skilled in the art will know from the above and following description that, unless otherwise notified, any combination of features relating to different subject matters, in addition to any combination of features belonging to one subject type, any combination of features relating to different subject matters, in particular any combination of features of device type claims, features of method type claims and features of use type claims, is also considered to be disclosed with the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The aspects defined above and further aspects of the invention are apparent from the examples of embodiment to be described hereinafter and are explained with reference to the examples of embodiment. The invention will be described in more detail hereinafter with reference to examples of embodiment but to which the invention is not limited.

[0054] Figure 1 The arrangement structure of an apparatus for detecting emission current in an X-ray tube according to an embodiment of the present invention is shown.

[0055] Figure 2 The arrangement structure of an apparatus for detecting emission current in an X-ray tube according to an embodiment of the present invention is shown.

[0056] Figure 3An example of magnetic field distribution in an apparatus for detecting emission current in an X-ray tube according to an embodiment of the present invention is shown.

[0057] Figure 4 The arrangement structure of an apparatus for detecting emission current in an X-ray tube according to an embodiment of the present invention is shown.

[0058] Figure 5 The arrangement structure of an apparatus for detecting emission current in an X-ray tube according to an embodiment of the present invention is shown.

[0059] Figure 6 An X-ray system comprising an apparatus for detecting an emission current in an X-ray tube according to an embodiment of the present invention is shown.

[0060] Figure 7 The figure shows an arrangement structure of a device including two Hall sensors according to an embodiment of the present invention. DETAILED DESCRIPTION

[0061] Figure 1 An arrangement is shown which comprises a device for determining an emission current 107 , 108 of an X-ray tube 100 . Figure 1 The arrangement structure of an X-ray tube 100 and a generator 101 is schematically shown, wherein X-ray tube wires 111 and 112 provide a connection between the X-ray tube 100 and the generator 101. Specifically, the X-ray tube 100 is operated by a filament driver 104, which is connected to a cathode and a filament 102 via X-ray tube wires 111, 112. The device includes a sensor 110 configured to determine an emission current 107, 108 of the X-ray tube 100, a first X-ray tube wire 111 and a second X-ray tube wire 112, which are configured to operate the X-ray tube 100. The sensor 110 is arranged at the first X-ray tube wire 111 and the second X-ray tube wire 112, or the sensor 110 is arranged near the X-ray tube wires 111, 112. As shown in Figure 1 As can be seen in FIG. 1 , the sensor 110 is arranged on the high voltage potential side of the X-ray tube 100, wherein Figure 1 The high voltage potential side in is the right side of the generator 101, where the high voltage 103 is connected to the X-ray tube wires 111, 112. On the left side of the generator 101, the generator 101 is connected to ground potential. The sensor 110 is arranged relative to the first X-ray tube wire 111 and the second X-ray tube wire 112, in particular so that the heating current 106 flowing through the first X-ray tube wire 111 flows in the opposite current direction to the heating current 105 flowing through the second X-ray tube wire 112. Figure 1, opposite current directions are indicated by arrows pointing to different sides (see 106 and 105). In addition, the sensor 110 is configured and arranged at the first X-ray tube wire 111 and the second X-ray tube wire 112 in such a manner that a first magnetic field 223 generated by the heating current 106 of the X-ray tube 100 in the first X-ray tube wire 111, a second magnetic field generated by the emission current 108 of the X-ray tube 100 in the first X-ray tube wire 111, a third magnetic field 224 generated by the heating current 105 of the X-ray tube 100 in the second X-ray tube wire 112, and a fourth magnetic field generated by the emission current 107 of the X-ray tube 100 in the second X-ray tube wire 112 are superimposed at the sensor 110. The sensor 110 is configured to measure a composite magnetic field generated by the superimposed magnetic fields at the sensor 110. In addition, the apparatus is configured to determine the emission currents 107, 108 of the X-ray tube 100 based on the composite magnetic field. The sensor 110 is further configured for generating a voltage signal based on the measured resultant magnetic field, wherein the arrangement is configured for determining an emission current 107 , 108 of the X-ray tube 100 based on the generated voltage signal of the sensor 110 .

[0062] Figure 1 The arrangement structure may also include a communication unit, which is not in Figure 1 The communication unit may be configured to send data at least including the determined emission current to at least one of the X-ray system, the generator 101, the X-ray tube 100 and / or an external analysis unit. The communication unit may be connected to the sensor 110 via an optical fiber, a digital bus and / or a wireless connection.

[0063] Figure 2 The arrangement details of the device 220, the sensor 110 located above the X-ray tube wires 111, 112, and the generated magnetic fields 223, 224 are shown. The sensor 110 is arranged above the X-ray tube wires 111 and 112, wherein in this embodiment, the wires 111, 112 are arranged adjacent to each other in the same plane. Due to the heating currents 221 and 222 flowing through the wires 111, 112, magnetic fields 223 and 224 are generated. Specifically, in the first X-ray tube wire 111, the heating current 221 generates a magnetic field 223, and the heating current 222 flowing through the second X-ray tube wire 112 in the opposite direction to the heating current 221 generates a magnetic field 224. The magnetic fields 223 and 224 and the magnetic field of the emission current not shown are superimposed at the sensor 110, wherein the magnetic fields 223 and 224 are reduced or offset. The first magnetic field is the magnetic field 223 shown, and the third magnetic field is the magnetic field 224 shown. The resultant magnetic field is the sum of the generated second magnetic field and the generated fourth magnetic field, and the apparatus is configured to determine the emission current of the X-ray tube according to the sum. Figure 2As can be seen in FIG. 1 , the sensor is arranged on a substrate 225 , wherein the substrate 225 is in particular a printed circuit board. The conductors 111 and 112 are arranged on the substrate 225 , and the conductors 111 and 112 may also be arranged in the substrate 225 . Figure 2 In the embodiment of the present invention, at least two X-ray tube wires 111, 112 are arranged below the sensor 110 (and on the substrate 225). The sensor 110 may be a Hall sensor for measuring a magnetic field.

[0064] Figure 3 A housing 330 is shown surrounding the sensor 110 and at least partially surrounding the first X-ray tube wire 111 and the second X-ray tube wire 112, wherein the housing 330 is configured to shield the sensor 110 from additional magnetic fields. Figure 3 The housing 330 in the embodiment includes a rectangular shape, wherein other shapes of the housing 330 are also possible. The shape of the housing 330 can be adapted to the geometry of the X-ray tube to which the device can be attached. The housing 330 is used to shield the device from external magnetic fields. Inside the housing 330, sensors and at least part of the X-ray tube wires 111, 112 can be arranged.

[0065] Figure 4 and Figure 5 Another embodiment of the present invention is shown, wherein the device 400, 500 comprises a magnetic core 440. The sensor 110 is arranged inside the gap d of the magnetic core 440, wherein the magnetic core 440 is in particular a toroidal magnetic core. The first X-ray tube wire 111 and the second X-ray tube wire 112 extend through the magnetic core 440, such as Figure 4 as shown, or wound around a magnetic core, as Figure 5 As shown. The heating currents flowing through the X-ray tube wires 111 and 112 are connected in such a way that the heating current flowing through the first X-ray tube wire 111 flows through the wire in the opposite direction to the heating current flowing through the second X-ray tube wire 112. The sensor 110 located in the gap d of the magnetic core measures the first magnetic field, the second magnetic field, the third magnetic field, and the fourth magnetic field, wherein due to the opposite flow directions of the heating currents, the heating currents are reduced and / or offset, so that the magnetic field contribution of the heating currents is almost zero. Therefore, the sensor 110 measures the residual magnetic field (the second magnetic field and the fourth magnetic field) of the emission current in the X-ray tube wires 111, 112.

[0066] Figure 6An X-ray system 660 is shown, which includes an X-ray tube 100 and a generator, at which a high voltage connector 661 is provided for connecting the X-ray tube wires 111, 112 and the cathode 662 of the X-ray tube 100. The cathode 662 can emit electrons and the anode 663 can collect electrons, so that a corresponding emission current is generated during the operation of the X-ray tube. The components of the X-ray tube 100 are arranged inside the housing 664, and according to this embodiment, the device including the sensor 110 is also arranged inside the housing of the X-ray tube. Therefore, the device is arranged inside the X-ray tube 100 and on the high voltage potential side. Specifically, the sensor 110 is arranged at the first X-ray tube wire and the second X-ray tube wire inside the X-ray tube 100. On the other hand, the sensor may be arranged at the first X-ray tube wire and the second X-ray tube wire on the high voltage potential side of the generator driving the X-ray tube 100. Figure 6 In the figure, the arrangement of the sensor 110 inside the X-ray tube is only schematically shown, because the specific arrangement depends on the corresponding X-ray tube in which the device is to be installed.

[0067] Figure 7An arrangement is shown in which at least two Hall sensors 110a and 110b are used to determine the emission current of an X-ray tube 100. The arrangement is shown only schematically. On the left, a generator 101 is arranged, from which X-ray tube wires 111 and 112 extend to the right, where the wires 111, 112 are connected to the X-ray tube 100. A first Hall sensor 110a is arranged at the first X-ray tube wire 111, and a second Hall sensor 110b is arranged at the second X-ray tube wire 112. The Hall sensors 110a, 110b can be arranged close to each other so that an external magnetic field does not have an influence. Alternatively, the Hall sensors 110a, 110b can be arranged spaced apart from each other. For example, the first Hall sensor 110a can be arranged on the high voltage potential side near the generator 101, or at the generator 101, while the second Hall sensor 110b can be arranged inside the X-ray tube (each arranged on the corresponding X-ray tube wire), or vice versa. The sensors 110a, 110b may be arranged in such a way that the heating current flowing through the first X-ray tube wire 111 flows along a current direction opposite to the heating current flowing through the second X-ray tube wire 112. On the other hand, the sensors 110a, 110b may be arranged so that the heating current flowing through the first X-ray tube wire and the second X-ray tube wire comprises the same current direction. Depending on the selected arrangement of the sensors 110a, 110b at the wires 111, 112, the amplifier 770 must perform a corresponding combination of the measured signals. For example, a subtraction or addition of the first voltage signal and the second voltage signal. The composite signal (or composite value in general) received at the output of the amplifier is the emission current signal 771, or the composite voltage signal at the output of the amplifier 770 is used to determine the emission current.

[0068] While the invention has been particularly illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

[0069] By studying the drawings, the present disclosure and the appended claims, those skilled in the art can understand and implement other variations to the disclosed embodiments when implementing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may perform multiple functions recited in multiple claims. Measures recited in mutually different dependent claims may be advantageously combined. Any reference signs in the claims should not be interpreted as limiting the scope.

[0070] List of reference numerals:

[0071] 100 X-ray tube

[0072] 101 Generator

[0073] 102 Filament

[0074] 103 High Voltage

[0075] 104 Filament Driver

[0076] 105, 221 Input heating current

[0077] 106, 222 Output heating current

[0078] 107 Emission current

[0079] 108 Emission current

[0080] 110 Sensors

[0081] 110a, 110b Hall sensor

[0082] 111 First X-ray tube wire

[0083] 112 Second X-ray tube wire

[0084] 200, 400, 500 units

[0085] 223 Magnetic field (output)

[0086] 224 Magnetic field (input)

[0087] 225 substrate

[0088] 330 Housing

[0089] 440 Core

[0090] 660 X-ray System

[0091] 661 High Voltage Connector

[0092] 662 cathode

[0093] 663 Anode

[0094] 664 Housing

[0095] 770 Amplifier

[0096] 771 Transmitting current signal

Claims

1. A device for determining an emission current of an X-ray tube (100), the device comprising: a sensor (110) configured to determine the emission current (107, 108) of the X-ray tube (100), a first X-ray tube lead (111) and a second X-ray tube lead (112) configured to operate the X-ray tube (100), The sensor (110) is arranged at the first X-ray tube wire and the second X-ray tube wire, wherein the sensor (110) is arranged on the high voltage potential side of the X-ray tube, wherein the sensor (110) is configured and arranged at the first X-ray tube wire and the second X-ray tube wire in such a manner that a first magnetic field generated by a heating current of the X-ray tube in the first X-ray tube wire, a second magnetic field generated by the emission current of the X-ray tube in the first X-ray tube wire, a third magnetic field generated by the heating current of the X-ray tube in the second X-ray tube wire, and a fourth magnetic field generated by the emission current of the X-ray tube in the second X-ray tube wire are superimposed at the sensor, wherein the sensor (110) is configured to measure a composite magnetic field generated by magnetic fields superimposed at the sensor, Therein, the apparatus is configured to determine the emission current of the X-ray tube based on the synthetic magnetic field.

2. The device according to claim 1, in, The sensor (110) is arranged relative to the first X-ray tube wire and the second X-ray tube wire so that a heating current flowing through the first X-ray tube wire flows in a current direction opposite to a heating current flowing through the second X-ray tube wire.

3. The device according to claim 1 or 2, in, The sensor (110) is further configured to generate a voltage signal based on the measured synthetic magnetic field. The device is configured to determine the emission current of the X-ray tube based on the voltage signal generated by the sensor (110).

4. The device according to any one of the preceding claims, in, The sensor (110) is arranged at the first X-ray tube wire and the second X-ray tube wire inside the X-ray tube, or The sensor (110) is arranged at the first X-ray tube wire and the second X-ray tube wire located on the high voltage potential side of the generator driving the X-ray tube.

5. The device according to any one of the preceding claims, wherein The device also includes: a housing surrounding the sensor (110) and at least partially surrounding the first X-ray tube wire and the second X-ray tube wire, The housing is configured to shield the sensor (110) from being affected by additional magnetic fields.

6. The device according to any one of the preceding claims, in, At least two X-ray tube wires are arranged below the sensor (110), wherein the at least two X-ray tube wires are the first X-ray tube wire and the second X-ray tube wire arranged below the sensor.

7. The device according to any one of the preceding claims 1 to 5, wherein: The device also includes: Magnetic core, The sensor (110) is arranged inside a gap of the magnetic core, wherein the magnetic core is in particular a toroidal magnetic core. The first X-ray tube wire and / or the second X-ray tube wire extend through the magnetic core or are wound around the magnetic core.

8. The device according to any one of the preceding claims, in, The sensor (110) comprises at least one Hall sensor for measuring a magnetic field.

9. The device according to any one of the preceding claims 1 to 7, in, The sensor (110) includes a first Hall sensor arranged at the first X-ray tube lead, and a second Hall sensor arranged at the second X-ray tube lead, Wherein, at the first Hall sensor, the first magnetic field and the second magnetic field are superimposed, Wherein, at the second Hall sensor, the third magnetic field and the fourth magnetic field are superimposed, wherein the first Hall sensor measures a first synthetic magnetic field, and the second Hall sensor measures a second synthetic magnetic field, The device is configured to determine the emission current of the X-ray tube based on the first synthetic magnetic field and the second synthetic magnetic field.

10. The device according to any one of the preceding claims, wherein The device also includes: a communication unit configured to send data at least comprising the determined emission current to at least one of an X-ray system, a generator of the X-ray tube and an external analysis unit, The communication unit is further configured to receive at least one of a measurement time for measuring the transmission current at a specific moment, a reference value of the transmission current, and a target value of the transmission current.

11. The device according to any one of the preceding claims, wherein The device also includes: at least one filter for filtering a residual heating current of the first X-ray tube wire and / or a residual heating current of the second X-ray tube wire, Wherein, the filter is an analog filter and / or a digital filter, Wherein, the bandwidth of the filter is about 1 kHz.

12. An X-ray tube, comprising: The device for measuring the emission current of an X-ray tube according to any one of claims 1 to 11, Wherein, the X-ray tube is operated via the first X-ray tube wire and the second X-ray tube wire of the X-ray tube.

13. An X-ray system comprising: X-ray tube, a generator configured to drive the X-ray tube, The device for measuring the emission current of an X-ray tube according to any one of claims 1 to 11, wherein the X-ray tube is operated by the generator via the first X-ray tube wire and the second X-ray tube wire of the X-ray tube, Therein, the device is configured to communicate with the X-ray system using a communication unit of the device.

14. A method for measuring an emission current of an X-ray tube, the method comprising: operating the X-ray tube using a first X-ray tube lead and a second X-ray tube lead, Arranging sensors at the first X-ray tube wire and the second X-ray tube wire, The step of arranging the sensor includes positioning the sensor on the high voltage potential side of the X-ray tube, Due to the configuration and arrangement of the sensor, a first magnetic field generated in the first X-ray tube wire by the heating current of the X-ray tube, a second magnetic field generated in the first X-ray tube wire by the emission current of the X-ray tube, a third magnetic field generated in the second X-ray tube wire by the heating current of the X-ray tube, and a fourth magnetic field generated in the second X-ray tube wire by the emission current of the X-ray tube are superimposed. measuring, by means of the sensor, a resultant magnetic field formed by the magnetic fields superimposed at the sensor, The emission current of the X-ray tube is determined based on the resultant magnetic field formed by the magnetic fields superimposed at the sensor.

15. Use of a Hall sensor for measuring an emission current of an X-ray tube, wherein the measurement is performed by superimposing a magnetic field generated by a heating current of the X-ray tube in a first X-ray tube wire, a magnetic field generated by the emission current of the X-ray tube in the first X-ray tube wire, a magnetic field generated by the heating current of the X-ray tube in a second X-ray tube wire, and a magnetic field generated by the emission current of the X-ray tube in the second X-ray tube wire, and by determining the emission current of the X-ray tube based on a composite magnetic field generated by the superimposed magnetic fields at the Hall sensor.

Images