Apparatus for performing an examination of an object by means of x-ray radiation

Abstract

The invention relates to a device for performing an examination of an object by means of X-ray radiation, wherein the device has a functional element which is movably arranged in a radiation region in a movement direction and a position sensor, the functional element having an electrically and / or magnetically conductive region, wherein the position sensor is an electric coil assembly for detecting the conductive region and for providing an overall voltage depending on the detection of the conductive region, wherein the coil assembly has an excitation coil for providing an alternating magnetic field and two series-connected detection coils for detecting at least a portion of the alternating magnetic field, wherein the detection coils and the excitation coil are arranged such that the overall voltage over the two detection coils is dependent on the position of the functional element relative to the position sensor, wherein the device is configured to derive a position signal dependent on the position of the functional element relative to the position sensor from the overall voltage.

Description

Technical Field

[0001] The present invention relates to an apparatus for performing inspection of an object by means of X-ray radiation, the apparatus comprising an X-ray source for outputting X-ray radiation, an X-ray detector for detecting at least a portion of the X-ray radiation output from the X-ray source, a radiation region constructed between the X-ray source and the X-ray detector, an object carrier for holding the object arranged in the radiation region for performing the inspection, an evaluation unit coupled to the X-ray detector for evaluating the radiation signal of the X-ray detector, particularly for inspecting the object, a functional element having an electrical and / or magnetic conduction region movably arranged in the radiation region along a direction of movement, and a position sensor, particularly for detecting the position of the functional element.

[0002] Furthermore, the present invention relates to a method for performing inspection on an object using X-ray radiation, wherein an X-ray source outputs at least a portion of X-ray radiation to a radiation region constructed between the X-ray source and an X-ray detector, wherein the X-ray detector detects at least a portion of the X-ray radiation output by the X-ray source and outputs a radiation signal based on the detected X-ray radiation, wherein the object is held by an object carrier arranged in the radiation region for performing the inspection, wherein the radiation signal from the X-ray detector is evaluated by means of an evaluation unit coupled to the X-ray detector, wherein a functional element having an electrical and / or magnetic conduction region moves in a direction of motion within the radiation region, wherein, in particular, a position signal is obtained, which is related to the position of the functional element relative to a position sensor. Background Technology

[0003] The type of equipment and methods used for examining objects using X-ray radiation are well-known in the prior art and therefore do not require separate literature verification in principle. This type of equipment, such as computed tomography (CT) machines and X-ray devices, is used to perform examinations on objects in order to at least partially determine their structure. Such examinations are commonly used in materials testing and also in the field of medical diagnostics, for example, for establishing diagnostics in biological materials, biology, etc. Therefore, the object can be, for example, the subject of an industrial manufacturing process, but can also be a decomposition product from mining, the body of a living organism, etc.

[0004] Furthermore, tomography is an imaging method that can provide, for example, a layered diagram of an object. Within the scope of tomography, the internal spatial structure of the object can be determined, and slice images can be created, for example. In particular, computed tomography is an imaging method in radiology. X-ray radiation is frequently used for this purpose. For example, X-ray radiation is directed at the object from different directions and detected using an X-ray detector. By evaluating the radiation signal, for example, the absorption value of the object to the X-ray radiation can be determined, and the structure of the object can be determined. The evaluation unit can be constructed as part of the device, or it can be connected to the device as a separate unit. As a result of the evaluation, imaging related to the object's structure can be set, for example.

[0005] Functional elements can be used to influence the function of the equipment, especially during the execution of an investigation. Therefore, functional elements can be, for example, collimators, to influence X-ray radiation in the radiation area. However, functional elements can also be used to detect inspection parameters, such as the temperature of the object, scattered radiation, etc., during the inspection. Typically, the functional element is at least partially exposed to X-ray radiation in the radiation area during the inspection. To adjust the effect of the functional element as needed, it can be moved along a direction of motion, preferably longitudinally. For this purpose, a separate drive can be provided, which can be controlled appropriately by means of the equipment's control unit, so that the functional element can be moved to the desired position.

[0006] To determine the position of a functional element, the device has a position sensor that detects the position of the functional element and transmits a corresponding position signal to the control unit. In many applications, this results in the position sensor also being at least partially exposed to X-ray radiation. Therefore, special requirements are placed on the design of the position sensor to achieve the highest possible accuracy in position detection, particularly in the face of high radiation resistance, especially with respect to X-ray radiation. In this case, DE 10 2022 206 622 A1 discloses, for example, a device for housing optical path components for X-ray radiation and a method for providing position information.

[0007] Especially when functional elements, such as filters and collimators, are present, their positioning within the radiation zone must be highly accurate to achieve the most precise possible inspection results. It is particularly crucial to monitor the corresponding current position of the functional elements so that unwanted changes or variations can be identified even in the absence of radiation. Therefore, driving functional elements to perform movement along the direction of motion is typically accomplished using one or more stepper motors (as drivers). The positioning of the stepper motors can be detected by proximity to one or more end stops and the resulting calibrable encoding. In stepper motors, end stop identification can be performed, for example, by sensing the motor current or by corresponding encoding devices, gratings, switches, etc. Common encoding devices operate, for example, using slotted disks and gratings, or also using disks and Hall sensors. However, such position sensors have proven to have limited tolerance to X-ray radiation and are also generally sensitive to mechanical tolerances, which can arise, for example, through rotation in a computed tomography (CT) scanner or during manufacturing, installation, or adjustment. Furthermore, the use of electronic circuit components, particularly program-controlled computing units, has proven to be limited in terms of reliability and expected lifespan restricted by X-ray radiation. Therefore, in the prior art, position sensors are typically shielded from X-ray radiation, as disclosed, for example, in DE 10 2022 206 622 A1.

[0008] It has also proven to be a disadvantage that, in existing technologies, the absolute or reference position of a position sensor cannot be directly detected, and potential deviations can lead to complex errors in the inspection results, which may only be painstakingly eliminated. Furthermore, the reliability of position sensors, especially regarding aging, is limited. Summary of the Invention

[0009] The objective of this invention is to improve a device and a method that can improve the radiation resistance of a position sensor and / or reduce radiation-induced aging of the position sensor.

[0010] As a solution, an apparatus and method according to the independent claims are proposed. Advantageous improvements arise from the features of the dependent claims.

[0011] In particular, it is recommended that the position sensor have an electrical coil assembly for detecting a conductive region and providing a position signal based on the detection of the conductive region, wherein the coil assembly has an excitation coil for providing an alternating magnetic field and two detection coils connected in series for detecting at least a portion of the alternating magnetic field, wherein the detection coils and the excitation coil are arranged such that the total voltage on the two detection coils is related to the position of the functional element relative to the position sensor, wherein the device is configured to obtain a position signal related to the position of the functional element relative to the position sensor based on the total voltage.

[0012] In particular, for this type of method, it is recommended to detect the conduction region using an electric coil assembly of a position sensor and to provide a total voltage based on the detection of the conduction region, wherein an alternating magnetic field is provided using an excitation coil of the coil assembly, wherein at least a portion of the alternating magnetic field is detected using two series-connected detection coils of the coil assembly, wherein the detection coils and the excitation coil are arranged such that the total voltage on the two detection coils is related to the position of the functional element relative to the position sensor, wherein a position signal related to the position of the functional element relative to the position sensor is obtained based on the total voltage.

[0013] This solution is also based on the concept that position detection can be reliably achieved using a position sensor, which does not need to have any moving parts. This has the advantage that mechanical wear on the position sensor is essentially negligible during normal operation over the predicted operating duration. Furthermore, using a position sensor with a coil assembly has proven advantageous, as the coil assembly can be implemented in a simple and particularly radiation-resistant manner.

[0014] Simultaneously, using a magnetic field as the medium for position detection allows for physical decoupling from X-ray radiation, enabling position detection results that are substantially unaffected by X-ray radiation. By using a coil assembly, the position sensor can be designed so that only the coil assembly needs to be placed within the radiation region, allowing all other components of the position sensor (those needed for the operation of the coil assembly and for position determination) to be placed substantially outside the radiation region. The separate, costly shielding of these components of the position sensor can therefore be reduced or completely eliminated.

[0015] Simultaneously, the coil assembly enables reliable detection of the functional element's position. This is because the total voltage is related to the position of the functional element, particularly the electrical and / or magnetic conduction region. Therefore, mechanical contact between the functional element and the position sensor is unnecessary. Furthermore, proximity to the end stop is also unnecessary, as the current position of the functional element can be reliably determined from the total voltage. The conduction region influences the geometry of the alternating magnetic field, which is detected by the detection coil. Therefore, a precise relationship can be established between the total voltage, which depends on the voltage induced by the detection coil, and the position of the functional element.

[0016] Preferably, the detection coils are arranged side-by-side along the direction of motion. The detection coils are preferably constructed to be substantially identical in their geometry. The detection coils are preferably constructed as flat coils and have corresponding windings having at least one, preferably multiple, turns. Particularly preferably, the windings of the detection coils have the same number of turns. For example, the detection coils can be constructed substantially as Archimedean coils. The cross-section of the detection coils and / or the excitation coils can be substantially circular or polygonal. The coils can be constructed as cylindrical coils, flat coils, Archimedean coils, etc. In particular, the excitation coils can have a different geometry than the detection coils.

[0017] A position sensor may have a single coil assembly. However, it is also possible, depending on the design of the device, for a position sensor to have multiple coil assemblies. It can be specified that the coil assemblies are arranged substantially adjacent to each other along the direction of movement of the functional element. In this way, it is also possible to detect particularly large movement paths using a position sensor.

[0018] The conductive region can be formed from conductive materials, such as metals or metal alloys. Alternatively or additionally, the conductive region can also be made from magnetizable materials, such as ferrites, magnetizable metals, or magnetizable alloys. The conductive region is preferably connected to the functional element as a separate component. However, the conductive region can also be constructed together with the functional element. The conductive region is preferably arranged in the device such that it can be loaded with an alternating magnetic field output from the excitation coil. Accordingly, the detection coil can detect the alternating magnetic field of the excitation coil. For this purpose, the excitation coil is loaded with a substantially constant alternating voltage or a substantially constant alternating current, so that the excitation coil correspondingly provides an alternating magnetic field.

[0019] X-ray detectors are particularly used to detect secondary X-ray radiation that is at least partially transmitted through the object, partially absorbed, and / or at least partially scattered by the object during an inspection, and to provide a detector signal as a radiation signal based on the detected secondary X-ray radiation. The detector signal can be evaluated by means of an evaluation unit so that the structure of the object can be at least partially determined. MHYaffe and HA Rowlands, for example, disclose X-ray detectors in X-ray Detectors for Digital Radiographie, Phys. Med. Biol. 42 (1997), pp. 1–39, which can be used, for example, in X-ray apparatuses and methods of this type.

[0020] This type of equipment, especially X-ray equipment, can have different designs. X-ray equipment suitable for X-ray tomography has proven particularly advantageous, in which digital slice images are obtained from the absorption values ​​of X-ray radiation passing through the object (which acts on the object, for example, from different directions), and the structure of the object can be seen from the digital slice images. Common in conventional X-ray methods is to apply X-ray radiation to the object to be examined, receive secondary X-ray radiation using an X-ray detector, and evaluate the radiation signal using an X-ray evaluation unit. The radiation signal is preferably an electrical signal, such as an analog or digital electrical signal. For evaluation, the evaluation unit can have electronic hardware circuitry and / or a program-controlled computing unit. The X-ray evaluation unit can also have an interface for providing the evaluation and / or output devices for outputting the evaluation.

[0021] Furthermore, in computed tomography, absorption profiles of an object can be established from multiple spatial directions, for example. The object's structure can also be determined from these profiles. With computer-aided image reduction, specific absorption levels can be determined for specific volumetric elements of the object, and the object's spatial structure can be determined in this way. X-ray tomography is an imaging method that can, for example, be used to visualize layers within an examined object.

[0022] Furthermore, it is suggested that the corresponding windings of the detection coils be selected such that the voltages induced by the series-connected detection coils cancel each other out in a preset reference position of the functional element relative to the position sensor. This can be achieved, for example, by having the winding directions of the detection coils be opposite to each other. Thus, when the detection coils are loaded with the same magnetic flux of an alternating magnetic field, the induced voltages can cancel each other out. This can be set in a specific position of the functional element. It is also stipulated in principle that complete cancellation of the induced voltages cannot be achieved. It is also possible that cancellation is determined by a local minimum of the total voltage. Therefore, preferably, the total voltage is substantially zero in the reference position. However, the total voltage can only have a local minimum in the region of the reference position.

[0023] Furthermore, it is suggested that the detection coils be arranged adjacent to each other in a plane parallel to the direction of motion. This method allows for particularly simple implementation of the position sensor function, as the two detection coils arranged side-by-side can be loaded with the same alternating magnetic field. Preferably, the excitation coils are also arranged in the same plane.

[0024] In principle, the excitation coil can also be constructed as a flat coil, wherein the excitation coil preferably surrounds the detection coil.

[0025] A particularly advantageous feature is that the series-connected detection coils are coupled to a capacitor on the detection side to form a resonant circuit on the detection side. It can be specified that the capacitor on the detection side is connected to the series circuit. However, it can also be specified that each detection coil is connected to a separate capacitor. In the multiple coil assemblies, the formed resonant circuit preferably has the same resonant frequency. This can significantly improve the sensitivity of the position sensor. The capacitor is preferably constructed as a ceramic capacitor, which has proven to be particularly resistant to X-ray radiation. However, in principle, the capacitor can also be formed by corresponding conductive surfaces that can be constructed opposite each other on the circuit carrier to provide corresponding capacitance.

[0026] Furthermore, it is suggested that the detection coil be arranged on a circuit carrier that provides a connection area located outside the radiation area, wherein the coil assembly is preferably at least partially located within the radiation area. This allows the detection coil to be implemented in a particularly simple manner. The circuit carrier can be, for example, a circuit board, or other plate-like insulating material on which the detection coil can be arranged. The detection coil can be constructed on the circuit carrier, for example, as a conductor track. The circuit carrier can be formed from, for example, a suitable material, such as plastic or ceramic, especially, for example, FR4. Particularly advantageously, the excitation coil is also arranged on the circuit carrier. In this way, the entire coil assembly can be provided as a single operable structural unit. The circuit carrier is preferably constructed such that the coil assembly can be arranged within the radiation area. Simultaneously, the circuit carrier provides a connection area, which is preferably located outside the radiation area. Therefore, additional components of the position sensor that should be connected to the coil assembly can be positioned outside the radiation area, thereby reducing or avoiding separate shielding against X-ray radiation.

[0027] Preferably, the excitation coil can also be connected to a capacitor on the exciter side, thereby forming a resonant circuit on the exciter side. The resonant frequency of the resonant circuit on the exciter side preferably corresponds to the resonant frequency of the resonant circuit formed by the detection coil and its capacitor.

[0028] Specifically, it can be specified that the detection coil is arranged planarly on a flat circuit carrier. The flat circuit carrier can be, for example, a circuit board.

[0029] It is particularly advantageous to demonstrate that the detection coil is arranged on a first surface of the circuit carrier, and the excitation coil is arranged on a second surface of the circuit carrier, which is different from the first surface and opposite to the first surface. In this way, current separation can be achieved between the detection coil and the excitation coil. Reliable functionality regarding the application of an alternating magnetic field to the detection coil can also be achieved through the circuit carrier, especially when the circuit carrier is constructed very thin. Preferably, the inner diameter of the excitation coil is selected such that the detection coil can be positioned within the inner diameter.

[0030] Furthermore, it is suggested that the series-connected detection coil be coupled to a capacitor on the detection side to form a resonant circuit on the detection side. The excitation coil is loaded with alternating current and / or alternating voltage by a frequency generator coupled to the excitation coil, wherein the frequency of the alternating current or voltage substantially corresponds to the resonant frequency of the resonant circuit on the detection side. Therefore, exceptionally high sensitivity of the position sensor in detecting the position of functional elements can be achieved.

[0031] It has been particularly advantageous to select a frequency in the range of approximately 800 kHz to approximately 1.6 MHz as the resonant frequency. It has been confirmed that particularly little interference occurs within this frequency range, thereby allowing for further improvement in the functionality of the position sensor.

[0032] Furthermore, it is suggested that the position signal and a processing signal having a processing frequency, particularly greater than the resonant frequency, be mixed by means of a first mixing unit to provide an intermediate frequency (IF) signal. Providing an IF signal enables improved signal processing, especially in terms of the accuracy of detecting the position of functional elements. The processing frequency is a preset frequency, which can be fixed for a specific application, for example. It can also be specified that the preset processing frequency can be changed or varied according to specific events. Even when the processing frequency can theoretically be selected to be less than the resonant frequency, the processing frequency is preferably greater than the resonant frequency. Particularly preferably, the processing frequency can be preset according to the resonant frequency. This makes it possible to provide an IF signal with a substantially fixed frequency, allowing a subsequent signal evaluation unit to be specifically adapted to the IF signal. This improves signal evaluation. Upmixing and downmixing can be implemented.

[0033] Furthermore, it is suggested that an intermediate frequency (IF) signal be filtered using an IF bandpass filter to provide an IF-filtered signal. This can particularly advantageously filter out interference and undesirable effects, thereby further improving reliability and functionality, especially in terms of the accuracy of the position sensor. It has been particularly advantageously demonstrated that an IF signal with a substantially constant frequency can be provided. Therefore, the IF bandpass filter can be constructed specifically adapted to this frequency, thereby improving the desired filtering effect.

[0034] Furthermore, it is recommended that the intermediate frequency (IF) signal, IF filter signal, and / or total voltage be sampled discretely over time. Therefore, the IF signal, IF filter signal, or sensor signal can be fed into digital signal processing. Digital signal processing can be performed using a programmable computing unit, such as a digital signal processor (DSP), FPGA, or ASIC. If the sensor signal has already been sampled discretely over time, subsequent signal processing can be performed almost entirely digitally.

[0035] According to the proposed improvement scheme, an intermediate frequency (IF) signal or IF filter signal and a difference frequency signal are mixed by a second mixing unit to provide a baseband signal. The frequency of the difference frequency signal essentially corresponds to the frequency difference between the position signal and the processed signal. This method enables demodulation that provides a baseband signal, which can be used almost unchanged as the position signal. Of course, the position signal can be provided based on the baseband signal, with additional processing steps possible, depending on the equipment requirements and design or the execution of the method.

[0036] Furthermore, it is suggested that the difference frequency signal have a frequency range from approximately 8.5 kHz to approximately 50 kHz. This frequency range has proven to be particularly advantageous for signal processing within the range of position detection.

[0037] Furthermore, it is suggested that the baseband signal be filtered using a low-pass filter to provide the position signal. This would allow for further improvements in the accuracy and reliability of the position signal.

[0038] The advantages and effects described for the device according to the invention also apply to the method according to the invention, and vice versa. Therefore, in particular, method features can also be expressed as device features, and vice versa. Features, combinations of features described previously, as well as features and combinations of features mentioned in the subsequent description of embodiments and / or shown only in the drawings, can be used not only in the separately described combinations but also in other combinations. Therefore, embodiments not explicitly shown and illustrated in the drawings, but which are derived from the described embodiments by separate combinations of features, are also included or considered disclosed by the invention. Attached Figure Description

[0039] The features, functions, and / or effects illustrated in the embodiments can each represent various features, functions, and / or effects of the invention that are considered independent of each other, and each also independently improves the invention. Therefore, embodiments should also include combinations different from those described in the illustrated implementations. Furthermore, the described implementations can be supplemented by other already described features, functions, and / or effects of the invention. Wherein:

[0040] Figure 1 A schematic diagram of an X-ray device is shown.

[0041] Figure 2 It shows that according to Figure 1 A schematic cross-sectional view of a fragment of the first design scheme for the position sensor of the device.

[0042] Figure 3 A schematic top view shows the situation according to... Figure 1 A fragment of the second design scheme for the device's position sensor;

[0043] Figure 4 It shows that according to Figure 3 A schematic circuit diagram of a position sensor.

[0044] Figure 5 It shows that according to Figure 4 The total voltage of the two series-connected detection coils in the coil assembly depends on the voltage of the two detection coils connected in series. Figure 1 A schematic diagram showing the position of the collimator in the device.

[0045] Figure 6 It shows that according to Figure 3 A schematic circuit block diagram of a position sensor. Detailed Implementation

[0046] Figure 1 The diagram illustrates an X-ray device 10 as a means of performing examinations on objects using X-ray radiation. The X-ray device is currently configured as an X-ray computed tomography (CT) device. The X-ray device 10 is used, for example, to perform X-ray examinations on patients. However, the X-ray device 10 is not limited to patients and can, in principle, be used on any object, such as for material inspection.

[0047] The X-ray apparatus 10 includes a patient positioning device 46, which itself has a moving stage 48 and a patient bed 50 movable relative to the moving stage 48 in the longitudinal direction 52 as an object carrier for holding the object (the patient). With the aid of the patient positioning device 46, the patient 12, arranged on the patient bed 50, can be positioned in the longitudinal direction 52 within a through-hole of the frame 54. The frame 54 is an annular support structure with the through-hole tunnel-shaped structure, allowing the examination area 30 of the patient 12 to be guided into the through-hole for X-ray examination. With the aid of the moving stage 48, the patient can be positioned in the through-hole of the frame 54 in a preset manner, so that the examination area 30 can be well loaded with X-ray radiation 14 on the one hand, and secondary X-ray radiation 20 can be well detected by means of the X-ray detector 18 on the other hand.

[0048] An X-ray source 16 for outputting X-ray radiation 14 is arranged in the annular region surrounding the through hole of the frame 54.

[0049] X-ray detectors 18 are arranged radially opposite each other in the annular region. The function, arrangement, and structure of suitable X-ray detectors are described, for example, in DE 10 2008 050 838. Therefore, reference is made supplementarily to the embodiments therein in this regard.

[0050] As from Figure 1As can be seen, the X-ray device 10 also has a control unit 56 that provides control signals 58, which allow the patient bed 50 to be positioned in the gantry 54. Furthermore, the control unit 56 provides control signals 60, which are also used to control the X-ray source 16 and the X-ray detector 18 in the gantry 54.

[0051] The X-ray device 10 also has a user interface 62, which can be used for at least some of the preset control signals 58, 60. The user interface 62 may include, for example, a joystick, a computer mouse, a keyboard, or a combination thereof.

[0052] The examination area 30 of patient 12 is examined such that patient 12 is moved into gantry 54 longitudinally 52 by means of patient bed 50. During this movement, preferably, X-ray source 16 and X-ray detector 18 move synchronously around patient 12 in a circular motion. X-ray source 16 emits X-ray radiation 14 that penetrates the examination area 30 of patient 12. Here, X-ray radiation 14 is partially absorbed, scattered, and / or deflected in the examination area 30 of patient 12, so that secondary X-ray radiation 20 escapes on the opposite side of the examination area 30. Secondary X-ray radiation 20 can be detected by means of X-ray detector 18. X-ray detector 18 provides a corresponding detector signal 22 as a radiation signal, which is transmitted to X-ray evaluation unit 24 (as evaluation unit). X-ray evaluation unit performs a corresponding evaluation of detector signal 22 and transmits the evaluated data to control unit 56. This data can be further processed in control unit 56 to, for example, convert the projected image into image information 64. Image information 64 can be transmitted from control unit 56 to display unit 66, which can provide a graphic visual display for users of X-ray equipment 10.

[0053] A radiation region 36 is constructed between the X-ray detector 18 and the X-ray source 16. An inspection region 30 is arranged, for example, within the radiation region 36. Furthermore, a collimator 26 is arranged as a functional element within the radiation region 36, and this collimator is movable along a direction of motion 32. For this purpose, the collimator 26 is coupled to a linear actuator (not shown further), which can be controlled by a control unit 56. The collimator 26 can be moved to a desired position within the radiation region 36 using the linear actuator. The X-ray radiation within the radiation region 36 can be influenced using the collimator 26.

[0054] Because information about the position of the collimator 26 is important for performing an examination on the patient 12, the X-ray device 10 has a position sensor 28 that detects the position of the collimator 26 in the radiation area 36 and transmits a corresponding position signal 34 to the control unit 56.

[0055] Figure 2 A fragment of a first design for the position sensor 28 is shown in a schematic circuit diagram. From Figure 2 As can be seen, the position sensor 28 has an electrical coil assembly 40, which is used to detect the conductive region 38 of the collimator 26. The coil assembly 40 is also used to provide a total voltage 68 based on the detection of the conductive region 38.

[0056] In the current design, the collimator 26 is mechanically connected to the ferrite via an unmarked coupling rod, and the ferrite forms a conductive region 38. This, in particular, forms a magnetically conductive region. In alternative designs, for example, an electrically conductive region could be provided, or both electrically and magnetically conductive regions could be provided.

[0057] from Figure 2 It can also be seen that the coil assembly 40 has an excitation coil 42, which is currently constructed as a cylindrical coil and connected to the generator 70, such that the excitation coil 42 can be loaded with an alternating current during normal operation, the alternating current having a substantially constant amplitude and a constant frequency. The generator 70 can currently be controlled by the control unit 56, so that at least the amplitude or frequency of the alternating current can be adjusted. However, it is also possible to load a corresponding alternating voltage onto the excitation coil 42.

[0058] from Figure 2 It can also be seen that the corresponding detection coil 44 is arranged adjacent to the axial end of the excitation coil 42 in the axial direction. The detection coil 44 is also constructed as a cylindrical coil and has essentially the same inner diameter as the excitation coil 42. The detection coil 44 is positioned coaxially with the excitation coil 42. The detection coils 44 are electrically connected in series and currently have the same number of turns, but with relatively opposite winding directions. Thus, a total voltage 68 is generated on the two detection coils 44, the total voltage corresponding, in particular, in terms of amplitude, to the difference in voltage induced in each detection coil. Due to the application of an alternating current, the excitation coil 42 provides an alternating magnetic field, which in turn flows through the detection coils 44.

[0059] Based on the design and electrical connection of the detection coil 44, in the conduction region 38... Figure 2A total voltage 68 is generated at the position shown, which is essentially approximately zero. Therefore, the voltages induced in each detection coil 44 cancel each other out. Once the collimator 26 and the corresponding conduction region 38 move in the direction of motion 32, the coupling of the detection region 44 relative to the excitation coil 42 changes, causing the amplitudes of the voltages induced in each detection coil 44 to differ from each other, and thus providing a total voltage 68 that is significantly different from zero. The amplitude of the total voltage 68 and / or the phase relative to the alternating current of the generator 70 can be correlated with the position of the conduction region 38 and, consequently, the position of the collimator 26. It is thus possible that the position signal 34 (which is derived from the total voltage 68) contains precise positional information regarding the conduction region 38 and, consequently, the collimator 26.

[0060] Currently, the coil assembly 40 is arranged near the collimator 26, i.e., within the radiation region 36. A connection region 72 is also provided, on which the total voltage 68 is supplied. The connection region 72 is currently located outside the radiation region 36. Therefore, the corresponding circuit assembly 80 for processing the total voltage 36 can also be arranged outside the radiation region 36. The current design of the position sensor 28 has the advantage that it does not require a mechanically movable part to be located there. Furthermore, the design of the position sensor 28 has proven to be particularly radiation resistant. Simultaneously, the position of the collimator 26 can be detected with high accuracy.

[0061] Figure 3 A second design for position sensor 28 is shown, which can also, in principle, be arranged in place of position sensor 28 according to... Figure 1 In the X-ray device 10. Regarding this design, please refer to the previous design. The differences from the first design of the position sensor 28 will be explained thereafter.

[0062] As from Figure 3 As can be seen, two coil assemblies 40 are arranged adjacent to each other on the circuit board 76 in the direction of movement 32 of the conduction region 38. The coil assemblies 40 are currently constructed substantially identically. For this purpose, Figure 4 A schematic circuit diagram of the position sensor 28 is shown.

[0063] In the current design, coil assembly 40 is formed on conductor plate 76 via conductor traces. Therefore, coil assembly 40 can be implemented particularly flat, i.e., space-saving and inexpensive. Coils 42 and 44 are arranged substantially in the same plane defined by circuit board 76. Coil assembly 40 has excitation coil 42, with exciter-side capacitor 82 connected in parallel with this excitation coil. Therefore, excitation coil 42 and exciter-side capacitor 82 form an exciter-side resonant circuit, which currently has substantially the same resonant frequency, substantially corresponding to the frequency of the alternating current supplied by generator 70. Alternatively, in the current design, the excitation coil 42 and detection coil 44 of the respective coil assembly 40 can be constructed on different opposing surfaces of circuit board 76.

[0064] Such external influence Figure 4 As can be seen, the two detection coils 44 of the coil assembly 40 are connected in series, wherein the detection coils 44 have the same number of turns but opposite winding directions. The detection coils 44 are constructed within the inner diameter of the excitation coil 42. The detection coils are arranged adjacent to each other in the direction of movement 32. In the current design, all detection coils 44 and excitation coil 42 are arranged adjacent to each other parallel to the direction of movement 32.

[0065] The total voltage 68 drops across the two detection coils 44 of the coil assembly 40. The total voltage 68 can be delivered to the circuit assembly 80 of the position sensor 28 via the connection area 72 (which may optionally be constructed on the circuit board 76). The circuit assembly 80 evaluates the total voltage 68 and provides the position signal 34 accordingly.

[0066] In addition, generator 70 is also connected to excitation coil 42, so that excitation coil 42 can be loaded with alternating current. In this design, two excitation coils 42 are connected to generator 70 in parallel.

[0067] In this design, the conduction region 38 is located within one of the coil assemblies 40 along the direction of motion 32, such that the position of the conduction region 38 and consequently the position of the collimator 26 can be precisely determined from the total voltage 68 of the respective coil assembly 40. The adjacent arrangement of the coil assemblies 40 is determined by the direction of motion 32. The positions of the two ends of the collimator 26 can be detected, for example, along the direction of motion 32, using two position sensors 28 on the same circuit board 76.

[0068] Furthermore, as can be seen from the second design of the position sensor 28, multiple coil assemblies can be selected according to the travel of the conduction region 38. Of course, the size of the coil assembly 40 itself can also be adapted as needed. The geometry of the corresponding coils 42 and 44 can also be varied as needed; for example, coils 42 and 44 can be constructed as circular, polygonal, or especially rectangular. The detection coil 44 can also be constructed as an Archimedean coil.

[0069] According to other design schemes, two opposing aperture jaw plates can be set, with the aperture gap for X-ray radiation 14 constructed between the aperture jaw plates. The aperture jaw plates can move relative to each other along the direction of motion 32 to adjust the width of the aperture gap. One of the two position sensors 28 arranged on the same circuit board 76 detects the position of one of the two aperture jaw plates, and the other position sensor of the two position sensors 28 arranged on the same circuit board 76 detects the position of the other aperture jaw plate.

[0070] from Figure 4 It can also be seen that the series circuit of the two detection coils 44 of the coil assembly 40 is connected in parallel with the capacitor 86 on the detection side. This creates a resonant circuit on the detection side, the resonant frequency of which is coordinated with the resonant frequencies of the excitation coil 42 and the capacitor 82. High sensitivity can be achieved through this arrangement.

[0071] The current design specifies that the frequency of the alternating current of the generator 70 is approximately 1 MHz. Although this frequency is relatively high, high sensitivity and resolution of the position can still be achieved using the position sensor shown.

[0072] Figure 5 The possible changes in the position signal 34, currently represented by voltage, are illustrated schematically as the conductive region 38 moves along the direction of motion 32. The voltage change process is shown in graph 84. If the conductive region 38 is outside the detection coil 44, then a voltage U2 is formed. Once the conductive region 38 reaches the region of the first detection coil of the corresponding coil assembly 40, the voltage drops to a value U3. At this point, the conductive region 38 has approximately reached the center point of the first detection coil 44. If the conductive region 38 moves further, the voltage increases until the conductive region 38 reaches the center point of the second detection coil 44 of the coil assembly 40. In this position, the voltage is U1. If the conductive region 38 moves further in addition, the voltage drops from value U1 to value U2, where the conductive region 38 again leaves the coil assembly 40.

[0073] The coil assembly 40 has proven to be particularly sensitive in the region 88 located between the two detection coils 44. In this region, the position of the conductive region 38 can be detected with exceptionally high precision.

[0074] Figure 6 The structure of the circuit component 80 connected to the connection area 72 is shown in a schematic circuit block diagram.

[0075] from Figure 6 As can be seen, generator 70 includes oscillator 90. Oscillator 90 provides an AC voltage, which is reduced to a desired sub-frequency by means of frequency divider 92. The desired frequency is adjusted by means of selection unit 94, which is currently about 1 MHz. However, the frequency can also be varied between 800 kHz and 1.5 MHz in steps of about 50 kHz when needed. A corresponding AC current is provided to excitation coil 42 in connection region 72 via amplifier 96.

[0076] The total voltage 68 is supplied to the first mixer 98 of the circuit assembly 80 via the connection region 72. The first mixer 98 mixes the total voltage 68 with the processing signal 100. The processing signal 100 is provided by the AC voltage of the oscillator 90 via the frequency divider 102 of the circuit assembly 80. The processing signal 100 has a frequency approximately 10 kHz higher than the frequency of the AC current of the generator 70. Therefore, an intermediate frequency signal 104 with a frequency of approximately 10 kHz is generated by mixing via the first mixer 98.

[0077] The intermediate frequency (IF) signal 104 is amplified by amplifier 106 of circuit assembly 80. Subsequently, the IF signal 104 is filtered by bandpass filter 108 of circuit assembly 80. Following bandpass filter 108 or the IF bandpass filter, there is an IF filter signal 122, which is sent to analog-to-digital converter 110 of circuit assembly 80. Currently, it is specified that the IF signal is sampled within the oversampling range of the analog-to-digital conversion. Further signal processing is performed digitally.

[0078] The signal digitized in this manner is downsampled in 112, and the signal generated in this manner is sent to the second mixer 114 of the circuit assembly 80.

[0079] Furthermore, a difference frequency signal 124 is supplied to the second mixer 114, which is generated from an AC voltage provided by the oscillator 90 by means of an additional frequency divider 116 and an operating time unit 118 of the circuit assembly 80. The frequency of the difference frequency signal 124 substantially corresponds to the difference between the frequency of the total voltage 68 and the frequency of the processed signal 100. Currently, the difference frequency signal 124 is specified to have a frequency of approximately 10 kHz. However, the frequency can also vary from approximately 8.5 kHz to 11.5 kHz as needed.

[0080] The second mixing unit 114 provides the baseband signal 126 as the result of mixing. Finally, the baseband signal 126 is filtered by the low-pass filter 120 of the circuit assembly 80 to provide the position signal 34.

Claims

1. An apparatus (10) for performing an inspection of an object (12) by means of X-ray radiation (14). in, The device (10) includes an X-ray source (16) for outputting X-ray radiation (14), an X-ray detector (18) for detecting at least a portion of the X-ray radiation (14) output by the X-ray source (16), a radiation region (36) constructed between the X-ray source (16) and the X-ray detector (18), an object carrier (50) arranged in the radiation region (36) for holding the object (12) in order to perform the inspection, an evaluation unit (24) coupled to the X-ray detector (18) for evaluating the radiation signal (22) of the X-ray detector (18), a functional element (26) having an electrical and / or magnetic conduction region (38) movably arranged in the radiation region (36) along the direction of motion (32), and a position sensor (28). The position sensor (28) has an electric coil assembly (40) for detecting the conductive region (38) and providing a total voltage (68) based on the detection of the conductive region (38). The coil assembly (40) includes an excitation coil (42) for providing an alternating magnetic field and two detection coils (44) connected in series for detecting at least a portion of the alternating magnetic field. The detection coils (44) and the excitation coil (42) are arranged such that the total voltage (68) across the two detection coils (44) is related to the position of the functional element (26) relative to the position sensor (28). The device (10) is configured to obtain a position signal (34) related to the position of the functional element (26) relative to the position sensor (28) based on the total voltage (68).

2. The device according to claim 1, in, The corresponding windings of the detection coils (44) are selected such that when the functional element (26) is located in a preset reference position relative to the position sensor (28), the voltages induced in each detection coil (44) cancel each other out.

3. The device according to claim 1 or 2, in, The detection coils (44) are arranged adjacent to each other in a plane parallel to the direction of motion (32).

4. The device according to any one of the preceding claims, in, The position sensor (28) has a capacitor (86) on the detection side. The detection coil (44) is coupled to the capacitor (86) on the detection side to form a resonant circuit on the detection side.

5. The device according to any one of the preceding claims, in, The device (10) has a connection area (72) which is electrically connected to the detection coil (44) and is designed to provide the total voltage (68) outside the radiation area (36). The coil assembly (40) is preferably arranged at least partially in the radiation region (36).

6. The device according to claim 5, in, The detection coil (44) is arranged planarly on a flat circuit carrier (76).

7. A method for performing an inspection on an object (12) by means of X-ray radiation (14), in, An X-ray source (16) outputs at least a portion of the X-ray radiation (14) to a radiation region (36) constructed between the X-ray source (16) and the X-ray detector (18), wherein the X-ray detector (18) detects at least a portion of the X-ray radiation (14) output by the X-ray source (16) and outputs a radiation signal (22) based on the detected X-ray radiation (14), wherein the object (12) is held by an object carrier (50) arranged in the radiation region (36) for performing an inspection, wherein the radiation signal (22) of the X-ray detector (18) is evaluated by means of an evaluation unit (24) coupled to the X-ray detector (18), wherein a functional element (26) having an electrical and / or magnetic conduction region (38) moves in the radiation region (36) along a direction of motion (32). The conductive region (38) is detected by means of the coil assembly (40) of the position sensor (28), and a total voltage (68) is provided based on the detection of the conductive region (38). The alternating magnetic field is provided by means of the excitation coil (42) of the coil assembly (40), wherein at least a portion of the alternating magnetic field is detected by means of two series-connected detection coils (44) of the coil assembly (40), wherein the detection coils (44) and the excitation coil (42) are arranged such that the total voltage (68) on the two detection coils (44) is related to the position of the functional element (26) relative to the position sensor (28). Among them, a position signal (34) related to the position of the functional element (26) relative to the position sensor (28) is obtained based on the total voltage (68).

8. The method according to claim 7, in, The detection coil (44) is coupled to the capacitor (86) on the detection side to form a resonant circuit on the detection side. The excitation coil (44) is loaded with AC current and / or AC voltage by a frequency generator (70) coupled to the excitation coil (42), and the frequency of the AC current and / or the AC voltage is coordinated with the resonant frequency of the resonant circuit on the detection side.

9. The method according to claim 7 or 8, in, The resonant frequency of the resonant circuit on the detection side is greater than 800kHz and / or less than 1.6MHz.

10. The method according to any one of claims 7 to 9, in, The total voltage (68) and the processed signal (100) are mixed by means of a first mixing unit (98) to provide an intermediate frequency signal (104). The processing signal (100) has a processing frequency, which is particularly greater than the resonant frequency of the resonant circuit on the detection side.

11. The method according to claim 10, in, The intermediate frequency signal (104) is filtered by an intermediate frequency bandpass filter (108) to provide an intermediate frequency filtered signal (122).

12. The method according to claim 10 or 11, in, At least the intermediate frequency signal (104), the intermediate frequency filter signal (122), and / or the total voltage (68) are sampled discretely in time.

13. The method according to any one of claims 10 to 12, in, On the one hand, the intermediate frequency signal (104) or the intermediate frequency filter signal (122) and on the other hand, the difference frequency signal (124) are mixed by means of a second mixing unit (114) to provide a baseband signal (126), wherein the frequency of the difference frequency signal (124) corresponds to the difference between the frequency of the total voltage (68) and the frequency of the processed signal (100).

14. The method according to claim 13, in, The frequency of the difference frequency signal (124) is greater than 8.5 kHz and / or less than 50 kHz.

15. The method according to claim 13 or 14, in, The baseband signal (126) is filtered by a low-pass filter (120) to provide the position signal (34).

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