X-ray rotating anode analysis system

Abstract

The present invention relates to an X-ray rotating anode analysis system for analyzing a used X-ray rotating anode having a revolving focal track on a surface section. The X-ray rotating anode analysis system includes a positioning device for the X-ray rotating anode, an image acquisition unit, and a data processing unit coupled to the image acquisition unit. The positioning device and the image acquisition unit are configured to position the X-ray rotating anode as an individual component at a predetermined position relative to the image acquisition unit. The image acquisition unit and the data processing unit are configured such that the image acquisition unit and the data processing unit can detect a three-dimensional height profile of the surface section of the X-ray rotating anode in the region of the focal track, and the data processing unit can determine a predicted radiation output or characteristic value of the X-ray rotating anode from the detected three-dimensional height profile or a portion thereof.

Description

Technical Field

[0001] The present invention relates to an X-ray rotating anode analysis system for analyzing a used X-ray rotating anode having a circumferential focus orbit on its surface portion. Further, the present invention relates to a method for analyzing such a used X-ray rotating anode.

[0002] The X-ray rotating anode is incorporated in an X-ray tube, and this X-ray tube is integrated into a corresponding X-ray apparatus. The X-ray rotating anode is used to generate X-rays as follows: During use, electrons are emitted from the cathode of the X-ray tube, accelerated in the form of a focused electron beam, and reach the X-ray rotating anode. Due to the rotational movement of the X-ray rotating anode, the electron beam scans an annular orbit, i.e., the focus orbit. Most of the energy of the electron beam is converted into heat at the X-ray rotating anode, while a small portion is emitted as X-rays. The locally emitted amount of heat strongly heats the X-ray rotating anode. The rotation of the X-ray rotating anode prevents overheating of the anode material.

[0003] Especially in the high-power field, a high radiation output of the emitted X-rays is required, which particularly applies to medical imaging applications such as computed tomography. Each time the material of the focus orbit moves under the electron beam due to rotation, the focus spot region on the surface of the focus orbit first undergoes a high temperature rise and thermally induced stress, and then the temperature decreases. As a result, the focus orbit deteriorates over time, which appears particularly as roughening of the surface, formation of cracks, generation of particles, and / or local melting.

[0004] The aging deterioration of the focal track results in a decrease in the emitted radiation output and a decrease in the stability of the operation of the X-ray tube. However, other effects such as the aging deterioration of the cathode (emitter), wear in the area of the bearing parts, and / or distortion of the X-ray rotating anode also lead to such reduction and / or deterioration. Therefore, it is a challenging task to evaluate what causes this. If the X-ray rotating anode is presumed or identified as the (common) cause, it is a problem to continue using it. As options, if the X-ray rotating anode is still functional, it can be continued to be used as it is; if the functionality can be restored, it can be readjusted (also called "reprocessing"; for example, reprocessing of the focal track, deletion and new establishment of the focal track, mechanical reprocessing in the area of the bearing parts, etc.), or otherwise, the X-ray rotating anode can be recycled, etc. This decision is often made subjectively by individuals through visual inspection of the X-ray rotating anode. From the perspectives of ecology, sustainability, and cost, it is desirable to process the X-ray rotating anode that can be continued to be used or readjusted in this way. In this case, the state of the focal track is an essential influencing factor regarding the continued use of the X-ray rotating anode.

[0005] An X-ray rotating anode test stand for evaluating a plurality of X-ray rotating anodes is known from Patent Document 1. Here, the X-ray rotating anode to be inspected is brought into the vacuum chamber of the test stand, rotated, and the area of its focal track is brought to the operating temperature by an electron beam. This test stand also has a temperature sensor for detecting the temperature of the X-ray rotating anode and a control device for evaluating the state of the X-ray rotating anode particularly according to the supplied heat and the detected temperature.

[0006] Furthermore, Non-Patent Document 1 describes a geometrical computational model that can determine the effect of surface morphology on the radiation output emitted from a medical X-ray tube. In this publication, multiple fixed X-ray anodes were exposed to a pulsed electron beam so that the surface morphology of their focal spot became that of an aged fixed X-ray anode, and the three-dimensional height profile of this surface was detected using laser scanning confocal microscopy (LSCM). Using the geometrical computational model, the reduction in radiation output due to the surface structure included in the three-dimensional height profile was determined compared to a smooth surface. Furthermore, the geometrical computational model was validated with experimentally compared values. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Chinese Patent Application Publication CN114428099A [Non-patent literature]

[0008] [Non-Patent Document 1] Siller, Maximilian, et al. "Geometrical model for calculating the effect of surface morphology on to total X-ray output of medical x-ray tubes." Medical Physics 48.4(2021):1546-1556 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] Therefore, the object of the present invention is to provide an analysis system for used X-ray rotating anodes removed from each X-ray tube, which can reliably and objectively evaluate the state of each X-ray rotating anode within its focal orbit range. [Means for solving the problem]

[0010] This problem is solved by the X-ray rotating anode analysis system described in claim 1 and the method for analyzing a spent X-ray rotating anode described in claim 14. Advantageous further embodiments of the present invention can be found in several dependent claims, which can be freely combined with one another.

[0011] The present invention provides an X-ray rotating anode analysis system for analyzing a spent X-ray rotating anode having a circumferential focal orbit on a surface section. This X-ray rotating anode analysis system comprises a positioning device for the X-ray rotating anode, an imaging unit, and a data processing unit coupled to the imaging unit. The positioning device and imaging unit are configured to position the X-ray rotating anode as a separate component (i.e., detached from the X-ray tube) relative to the imaging unit. The imaging unit and data processing unit are configured to detect a three-dimensional height profile of the surface section of the X-ray rotating anode in the region of its focal orbit, and to determine the predicted radiant power or characteristic value of the X-ray rotating anode from or a portion of the detected three-dimensional height profile.

[0012] The predicted radiation output determined via a three-dimensional height profile is generally an important criterion for the predicted power performance of an X-ray rotating anode and, in particular, the state of its focal orbit. The surface morphology of the focal orbit is a significant influencing factor to the emitted radiation output, because non-smoothness results in local absorption effects of emitted X-rays. Therefore, this determined predicted radiation output is important for decisions regarding the continued use of the X-ray rotating anode in question. Further advantageous analyses are also possible based on this three-dimensional height profile, which will be described with reference to further embodiments. The automated determination of the predicted radiation output by this X-ray rotating anode analysis system is inherently advantageous because it is particularly objective compared to visual assessment of an X-ray rotating anode by an individual and allows for the inclusion of significantly more data and detail. Compared to evaluation methods performed on an X-ray rotating anode in an X-ray tube, such as direct measurement of emitted radiation output and / or evaluation of backscattered electrons, the X-ray rotating anode analysis system according to the present invention has the advantage that the state of the focal orbit is directly detected and the results of the analysis are not adversely affected by other influencing factors (e.g., aging of the cathode, filters, etc. used). This X-ray rotating anode analysis system is a separate system from the X-ray apparatus or X-ray tube, and in particular, it does not have a vacuum valve or a unit for accelerating the electron beam toward the X-ray rotating anode. Finally, the present invention advantageously utilizes multiple automated calculation options that enable the processing of large amounts of data by using a properly configured data processing unit. At the same time, by using an image acquisition unit and positioning device, it is not necessary to use expensive components that are used in other evaluation methods (e.g., when generating an electron beam, when detecting the spectrum of backscattered electrons, etc.).

[0013] Here, “used X-ray rotating anode” is not part of the claimed X-ray rotating anode analysis system and is mentioned solely to describe the function and design of the X-ray rotating anode analysis system. The term “focal orbit” refers at least to the (annular) surface region of the X-ray rotating anode that is scanned by the electron beam when the X-ray rotating anode is in use. Often, the X-ray rotating anode has an annular layer (above the carrier body formed underneath) in this surface region and, possibly in a region directly adjacent thereto, which is specifically designed to generate X-rays. Suitable materials for this layer are those with a large atomic number, such as tungsten, tungsten alloys, and especially tungsten-rhenium alloys (e.g., with a rhenium content up to 26 wt%, preferably in the range of 5-15 wt%, actually typically in the range of 5-10 wt%). In the latter case, the term “focal orbit” refers to the annular layer of the X-ray rotating anode. In this case, the design of the X-ray rotating anode defines axial directions (along or parallel to the axis of rotation to which the X-ray rotating anode is substantially rotationally symmetric; also called the z-direction), circumferential directions (orbiting around the axis of rotation in a plane perpendicular to the axis of rotation), and multiple radial directions extending away from the axis of rotation in a plane perpendicular to the axis of rotation (in this case, the main extending surface of the X-ray rotating anode ultimately extends). The x and y directions also run in this plane, with the y direction corresponding to the X-ray emission direction. The surface section from which the three-dimensional height profile is detected can extend over or cover the entire orbiting focal orbit. However, it can also include only one or more sub-regions thereof, in particular the region actually scanned by the electron beam in the radial direction (especially in the case of a focal orbit layer formed more radially than horizontally), and / or at least one sector or another (e.g., rectangular) portion in the circumferential direction. In this case, preferably, the at least one subregion contained therein is a region that represents the surface morphology of the focal orbit, or alternatively, it may be, for example, the most severely damaged region, which can be evaluated using a simple (e.g., only two-dimensional) overview image of the focal orbit created initially.Since the surface of the focal orbit is generally curved and inclined with respect to the principal extending plane (which generally corresponds to the shape of the frustum lateral surface), appropriate corrections using known methods must be made so that the height of individual image points in the 3D height profile accurately reproduces the ideal shape of the (theoretically assumed) smooth focal orbit (i.e., the frustum lateral surface).

[0014] When determining the "predicted radiant power," the entire relevant (wavelength) spectrum of the X-ray emission is included, as is the case when an X-ray rotating anode is actually used. Furthermore, preferably, filtering typical in an X-ray apparatus is also applied, depending on the operating conditions, particularly to reduce the long-wavelength radiation component. Preferably, the kinetic energy released into the air (KERMA: kinetic energy released into the material) is used as the reference physical quantity for radiant power. This is measured in the physical unit Gray (joules / kilogram) and indicates how much energy (joules) is released per kilogram of material (in this case, air), and in this case, the entire relevant radiation spectrum (i.e., over all wavelengths) is summed up. However, it is also possible to determine other effective physical quantities specific to radiant power. For example, the reduction of predicted radiant power due to the surface morphology of the focal orbit, the ratio of predicted radiant power to the reference radiant power of a smooth focal orbit surface, or different definitions / expressions of radiant power, and / or no filtering or application of different filtering.

[0015] This positioning device is designed to position the X-ray rotating anode as a “separate component,” i.e., detached from the X-ray tube. In particular, the positioning device can engage with or abut against a centrally mounted handle, circumferential portion, and / or the underside of the X-ray rotating anode opposite the axial focal orbit, for positioning in the central opening / bore. In addition to abutment and / or engagement, the positioning device can also be designed for fixation, and, in addition, to rotate the X-ray rotating anode around its axis of rotation, as needed.

[0016] In this case, the positioning device, image acquisition unit, and data processing unit can all be integrated into the same overall device. However, alternatively, they can be formed as multiple separate units; in this case, the important thing is that the positioning device can accurately position the X-ray rotating anode being inspected relative to the image acquisition unit (this can be achieved, for example, by properly holding the image acquisition unit relative to the positioning device). Furthermore, the integration of the data processing unit with the image acquisition unit is essential so that at least multiple data sets (multiple image data) can be transferred from the image acquisition unit to the data processing unit. In particular, they are in a state where they can communicate and exchange data with each other. The data processing unit itself can be fully integrated into the image acquisition unit, but all or part of it can also be separated into at least one other device.

[0017] The use of data processing units is a computer-supported method. Detection of the 3D height profile and determination of the predicted radiant output are performed according to at least one algorithm, which can be executed by one or more well-configured software modules. That is, both steps are software-supported. The 3D height profile contains height information for each image point (pixel) along the total area of ​​the detected surface section. This is particularly true for 3D height profiles created by high-resolution imaging. Work is performed in all three spatial directions, particularly at a resolution of ≤5 μm, preferably ≤4 μm. This resolution can be increased by special methods, particularly by capturing more individual images with an imaging unit and processing the resulting multiple image data accordingly. Achieving high resolution, especially in the height direction, is advantageous considering the shielding effect of raised surface structures (in fact, resolutions of ≤1 μm can be achieved in all three spatial directions). In this case, the predicted radiant output can be determined from the entire detected 3D height profile or from only partial information therefrom. As described below with reference to another embodiment of the present invention, for example, a surface profile covering only a portion of the detected surface section can be used as a basis, or one or more line profiles can be used as a basis.

[0018] In a further embodiment, the imaging unit and data processing unit are configured to use electromagnetic radiation (particularly in the wavelength range of 10 to 3,000 nm; nm: nanometers) to create multiple separate images, each containing different depth information of the surface section of the X-ray rotating anode being analyzed, and from these separate images, the data processing unit can reconstruct a three-dimensional height profile of the surface section being analyzed. This is an efficient method for creating a three-dimensional height profile, and it can be implemented at a favorable cost, especially given the low cost of the computer performance and equipment available today. In this case, the electromagnetic radiation used may be a spectrum containing multiple wavelengths or it may be monochromatic. Furthermore, the electromagnetic radiation used may have a large wave coherence length (laser), in which case it is typically monochromatic radiation. Essentially, there are various possibilities known in the prior art for creating multiple separate images and then creating a three-dimensional height profile from them. In this case, the imaging unit preferably operates according to optical methods. For example, these individual images can be taken from multiple different angles and then combined to create a three-dimensional height profile (photogrammetry). Alternatively, for example, using a laser scanning confocal microscope (LSCM) inspection method, the focus of the optical system can be adjusted stepwise to multiple heights (e.g., perpendicular to the plane of the surface section being analyzed) (preferably in steps of ≤0.5 μm, e.g., 100 nm; modern instruments can adjust even significantly smaller step widths), and multiple sharply imaged subregions can be captured as multiple individual images, which can then be combined to create a three-dimensional height profile.

[0019] In a further embodiment, the image acquisition unit and data processing unit are configured to create multiple individual images of the surface section to be analyzed from multiple different angles, particularly using electromagnetic radiation in the wavelength range of 380 nm to 780 nm (which corresponds to the visible range of the human eye). By changing the shooting direction, corresponding multiple depth information (axial, i.e., in the z-direction) can be obtained. Furthermore, preferably, the illumination angle of the surface section is also changed together with the shooting direction or independently of each shooting direction, and the shadows projected by multiple surface structures of the surface section to be analyzed are also evaluated. In particular, it is possible to work with "white" light covering the spectrum across this wavelength range. In this way, the image acquisition unit (camera) can operate by (optical)optics techniques and can acquire multiple individual high-resolution images in an efficient and cost-effective manner. In particular, the image acquisition unit can acquire multiple individual images at a corresponding magnification (e.g., in the range of 5 to 20 times, particularly 10 times). A three-dimensional height profile can then be created from multiple individual images (number ≥ 2) taken from multiple different angles. The principle here is that increasing the number of individual images taken from multiple different angles of the surface section being analyzed can increase the resolution of the resulting three-dimensional height profile. Therefore, the number of individual images obtained from multiple different angles of the surface section being analyzed is preferably 20 or more, more preferably in the range of 50 to 100. This principle also applies to alternative modifications in which the focus is adjusted stepwise (preferably in steps of ≤0.5 μm, for example in steps of 100 nm) to different heights, and multiple sharply imaged subregions are taken as multiple individual images, in which case a number of individual images ≥200, particularly ≥500, is preferred. If a step width of 100 nm is set and a height range of, for example, 100 μm is covered, this corresponds to, for example, 1000 individual images.

[0020] According to a further embodiment, the data processing unit is configured to determine the predicted radiant output or characteristic value of the X-ray rotating anode, based on the automatically calculated absorption of X-rays along the X-ray emission direction according to the detected three-dimensional height profile, taking into account local absorption effects due to local surface changes or surface structures. An advantage of this further embodiment is the average roughness R a Or mean square roughness R q Not only are one or a few individual physical quantities characteristic of or describing the overall surface morphology used, but absorption at each (local) surface change (e.g., bulging, cracking, particle generation, local melting) present in the analyzed surface section is determined, and its effect on the predicted radiation output is taken into account. This also allows for additional analysis options, such as the confirmation of significant local damage (e.g., large cracks or particle generation) and / or the confirmation of predicted radiation output variations occurring in the circumferential direction, which may lead to a different evaluation of the X-ray rotating anode, even if the surface morphology of the surface region around the focal orbit as a whole is acceptable. This determination is performed using algorithms that can be executed by one or more appropriately equipped software modules, particularly with computer support (i.e., using a data processing unit). In this case, considering all local absorption effects (i.e., for example, per image point or pixel, or per coordinate of the surface section or line profile included) is possible with the computer capabilities available today. The so-called "X-ray emission direction" is determined by the shape of each X-ray rotating anode. Typically, the section of the rotating X-ray anode on which the focal orbit is formed corresponds to the side of a frustum of a cone, which is inclined by a certain angle (e.g., 10°) with respect to the radial direction (with respect to the axis of rotation). Since the X-ray emission direction in each X-ray apparatus generally extends precisely along the radial direction, it is inclined by an angle (e.g., 10°) with respect to its side and therefore to the surface of the focal orbit (which is locally approximated as a plane).

[0021] In a further embodiment, the data processing unit is configured to allow the use of at least one line profile for automatically calculating X-ray absorption, the at least one line profile extending in the X-ray emission direction over a predetermined minimum length along a detected surface section of the X-ray rotating anode and having local surface changes or surface structures according to a three-dimensional height profile. This further embodiment allows for a reduction in the required computer performance by selectively using one or more line profiles. Each line profile represents a height difference (height distribution) along a specified extension direction according to a three-dimensional height profile. In this case, each line profile extends in the X-ray emission direction along a detected surface section of the X-ray rotating anode over at least the extent of the focal spot in this direction. This minimum distance needs to be referenced because, as is known, the electron beam is not focused precisely to a point on the rotating X-ray anode but has a finite spread (i.e., a focal spot) on the focal orbital surface with a specific electron intensity distribution (see Rolf Behling, "Modern Diagnostic X-Ray Sources," 2nd edition, 2021, pp. 226-231). In this case, the focal spot can be the focal spot size specific to each X-ray tube in which the rotating X-ray anode is installed (if known), or a commonly used focal spot size, and the electron intensity distribution on the focal orbital surface (e.g., a range of 4-12 mm, especially a range of, for example, 10 mm, the maximum distance in at least one direction; however, in some cases, only the subregion with the highest electron intensity may be used). Furthermore, it should be explained that, due to the inclination angle typically formed on the focal trajectory (on the side surface of the frustum) with respect to the X-ray emission direction (typically corresponding precisely to the radial direction), this line profile is obtained from the projection (along the axial direction) of the X-ray emission direction onto the detected surface section, which is expressed by the summary above, "in the direction of X-ray emission over a predetermined minimum length along the detected surface section."As explained below regarding the simplification / approach section 2, the use of such multiple line profiles and approximating the focal spot as a linearly running and appropriately tuned intensity profile is particularly advantageous for X-ray rotating anodes, as they are rotated at high speed during use.

[0022] In a further embodiment, the data processing unit is configured to allow the use of at least one surface profile for the automatic calculation of X-ray absorption, the at least one surface profile extending in the direction of X-ray emission over a predetermined minimum length along the detected surface section and over a predetermined minimum width substantially perpendicular thereto, and having local surface variations according to a three-dimensional height profile. Including at least one surface profile has the advantage that all surface variations on the included surface are included in the calculation. In this case, each surface profile reproduces the height distribution according to the three-dimensional height profile of each pixel in the included surface. The above description of the length and distribution of line profiles also applies to its minimum length and distribution. As for its width, the included plane can be particularly sector-shaped (i.e., the inner and outer sides extend circumferentially, with the inner extension being smaller than the outer extension). However, the surface profile can also be of other shapes.

[0023] In both the linear profile-related unfolded form and the surface profile-related embodiment, only a single (e.g., representative) linear or surface profile, which extracts only the linear or surface section of the focal trajectory, can be used for determination. In particular, multiple linear or surface profiles preferably evenly distributed circumferentially across the circumferential focal trajectory can be used. Furthermore, they may cover or include the entire circumferential focal trajectory.

[0024] According to a further embodiment, this data processing unit takes the following input variables, namely: The X-ray emission depth (within the focal orbit) correlates with the penetration depth of the electron into the focal orbit being analyzed. X-ray emission angle, Material of the focal orbit of the X-ray rotating anode, Size of the focus spot, The electron intensity distribution at the focal spot, and, filter, At least one of these is set to be included in the automatic calculation of X-ray absorption.

[0025] By considering these input variables, the accuracy and reliability of determining the predicted radiant output are improved. The electron penetration depth into the focal orbit to be analyzed is essentially an intensity distribution over depth, which depends on the electron acceleration voltage. Therefore, the X-ray emission depth correlated with this is also an intensity distribution (which does not precisely correspond to the intensity distribution of the electron penetration depth, particularly due to absorption effects). However, for simplicity, an average value of, for example, 1.6 μm (μm: micrometers) can be used as the X-ray emission depth at an assumed acceleration voltage of 100 kV (kV: kilovolts) (literature values ​​are in the range of 1.0 to 1.6 μm). The X-ray emission angle corresponds to the tilt angle described above (usually 10° or 7°), which must be taken into consideration when determining the path length of the emitted X-rays through the material in the focal orbit and the resulting (material-dependent) absorption of the X-rays, based on the assumed X-ray emission depth. The generated X-ray emission spectrum can be determined depending on the material of the focal orbit of the X-ray rotating anode and the assumed acceleration voltage, for example, 100 kV (kV: kilovolts) (available from publicly accessible sources). Furthermore, since the absorption of the generated X-rays before they exit the surface of the focal orbit depends on the material of the focal orbit (as well as the respective wavelengths of the X-ray spectrum), the material of the focal orbit is preferably considered when determining the emission power. The above description applies to the size of the focal spot and the electron intensity distribution (they can be specified, depending on the calculation method, as an intensity distribution across a surface or as a linear intensity distribution, along with the corresponding size in each case). Furthermore, filtering is used in the X-ray apparatus (for example, by borosilicate glass used as a component of the radiation path, and / or by aluminum or copper as a specific wavelength-dependent filter; both are collectively referred to as "filters" or "filtering"). Special wavelength-dependent filters (e.g., made of aluminum or copper) are used to reduce the proportion of long-wavelength radiation (also called "soft" radiation) because this long-wavelength radiation contributes little to or no to imaging and can cause unnecessary radiation exposure.Therefore, it is preferable that wavelength-dependent filtering using such filters typically used in X-ray apparatuses (e.g., 2.5 mm borosilicate glass filters and 2 mm aluminum filters) is included in the determination of the predicted radiant power.

[0026] In a further embodiment, the data processing unit is configured to identify and classify damage in a region of the surface section of the focal orbit of an X-ray rotating anode, either from a detected three-dimensional height profile of the surface section of the focal orbit or from multiple image information detected by other means. In addition to determining the predicted radiation output, identifying and classifying damage according to its type, such as roughening, local melting, cracking, and particle generation, and / or according to its severity, such as height / depth and lateral expansion, is another important criterion for evaluating the state of the focal orbit and thus helps in issuing a recommendation for continued use of the X-ray rotating anode in question. In a further embodiment, individual images taken from different angles of the surface section to be analyzed form the basis for creating image information acquired by other means. In this case, in particular, coordinates (in all three spatial directions), RGB values ​​(R: red component, G: green component, B: blue component in additive color space), and B / W values ​​(B: black component, W: white component in grayscale representation) can be assigned to each image point, and other information can be assigned as needed. Based on this, various two-dimensional contrast representations of the analyzed surface section can be created, and based on this, multiple damages to the focal orbit of the X-ray rotating anode within the surface section area can be identified and classified particularly well, either individually or by combinations of multiple such contrast representations. In addition, multiple image information acquired by other methods can be derived from three-dimensional height profiles (e.g., representations of minimum and maximum heights), or formed from or derived from multiple images taken separately with special camera settings. For example, cracks that extend deep into the material of the focal orbit or cracks that penetrate the entire focal orbit layer, and / or localized melting that results in significantly raised molten beads on the surface of the focal orbit can be indicators that the focal orbit needs to be extensively reworked (e.g., by removing a significant portion of the focal orbit or even the entire focal orbit layer, and further by recoating the focal orbit material), and that surface grinding alone is insufficient.

[0027] Such automated identification and classification are performed with software support. This software can be configured and set up to learn this identification and classification by machine learning, or in a manner previously learned. As part of this machine learning, the software is trained by a person skilled in the art to identify and classify ("label") damage in a number of corresponding exemplary images (e.g., a three-dimensional height profile of a surface portion of a focal orbit or other image information obtained by other means), in which case the software is given access to the exemplary images, as well as their identification and classification. The software is configured to identify and learn patterns from sample images using an applied learning strategy. The quality of identification and classification by this software improves with the number and quality of the provided, i.e., "labeled" exemplary images. Furthermore, identification and classification are facilitated by a proper representation of the surface section in question, and as a result, the software can also be performed on image information obtained by other means.

[0028] In a further embodiment, the image acquisition unit and data processing unit are configured to detect at least one image of another surface section in a region adjacent to the focal orbit of the X-ray rotating anode. This allows for additional conclusions to be drawn about the quality of other regions of the X-ray rotating anode that may be located, for example, on the same side (front side) of the focal orbit, or on the opposite side (back side) of the focal orbit when viewed axially. As described above, a three-dimensional height profile or multiple image information detected in other ways can also be generated from this at least one image acquisition, and further analysis can be performed based on this.

[0029] In a further embodiment, the data processing unit is configured to evaluate several subsequent use options for the X-ray rotating anode based on the determined predicted radiation output or based on characteristic values, and to issue corresponding use recommendations (e.g., via a display or a display unit of the data processing unit). Thus, since the issued use recommendations are based on an objective evaluation of the X-ray rotating anode considering the state of the focal orbit, in particular, both X-ray rotating anodes that are directly usable for continued use, or those that can be repaired by reprocessing (also called "reworking"), can be used for subsequent use in a way that conserves such resources. In this case, in addition to the predicted radiation output, other criteria such as damage to the focal orbit or conditions in other areas of the X-ray rotating anode can also be included in the evaluation. In particular, the further use recommendations include several options, namely: Direct and continuous use of X-ray rotating anodes, Surface polishing of the focal orbit surface, Localized repair of the focal orbit in severely damaged areas (e.g., localized removal and reapplication of the focal orbit material), Mechanical removal of a large area of ​​the entire focal orbit material (especially the entire focal orbit layer) or removal of the corresponding surface area, followed by application of the focal orbit material, and optionally, followed by smoothing of the applied focal orbit material (e.g., by grinding). Mechanical rework of the X-ray rotating anode outside the focal orbit region (e.g., in the fixed region of the axis to eliminate rotational imbalance), Recycling of X-ray rotating anodes (in case of irreparable damage), In the case of direct, continuous use, or use after reprocessing, this further recommendation of use additionally includes recommendations for specific operating conditions (e.g., operation with specific parameters, or operation with a specific X-ray tube or X-ray apparatus). It may include one or more of the following.

[0030] According to a further embodiment, the data processing unit is coupled to a memory unit which can be located in particular on a single device / memory or alternatively distributed across multiple devices / memories (in particular, they communicate with each other and exchange data), and the data processing unit and the memory unit are configured for at least one of the following interactions: For each X-ray rotating anode analyzed, the individual information determined, such as the detected 3D height profile, line profile, surface profile, individual images, other detected image information, damage, determined predicted emission power, and issued next-use recommendations, obtained from the region of its focal orbit and / or adjacent to that focal orbit, can be stored in a memory unit by this data processing unit and read from that memory unit (e.g., individualization by automated identification of the X-ray rotating anode's serial number). Type-specific information for multiple different types of X-ray rotating anodes, such as drawings, structures (including connection techniques used, coatings, etc.), manufacturing data (including unique identification numbers assigned to each X-ray rotating anode during manufacturing), transport data, dimensions of the X-ray rotating anode, and materials of the X-ray rotating anode (particularly the focal orbit and the anode disk formed beneath it), can be stored in a memory unit by this data processing unit and read from that memory unit. For each X-ray rotating anode analyzed, the usage data obtained, such as load cycles, usage period, rotation speed, acceleration voltage applied between the cathode and the X-ray rotating anode, cathode type, focal spot size, and electron intensity distribution, can be individually stored in a memory unit by this data processing unit and read from that memory unit. The individual histories of each analyzed X-ray rotating anode regarding its use in-situ (i.e., within the X-ray apparatus) and subsequent processing and repairs (e.g., those performed after analysis by the X-ray rotating anode analysis system throughout its lifecycle) can be stored in a memory unit and read from that memory unit. In this way, this X-ray rotating anode analysis system allows for the tracking and documentation of the entire "lifecycle history" of an X-ray rotating anode. In this case, this memory is specifically recorded along with relevant date reference dates ("date stamps"). Based on this database, it is possible to make better predictions / recommendations regarding the next usage options when analyzing a particular X-ray rotating anode. This can sometimes be summarized under the keyword of lifecycle management.

[0031] According to a further embodiment, the data processing unit evaluates the following further information in the evaluation of subsequent usage options for the X-ray rotating anode, namely, Uniformity of the three-dimensional height profile along the circumferential direction of the X-ray rotating anode. Damage to the focal orbit of the X-ray rotating anode in the surface section region, Image of another surface section in a region adjacent to the focal orbit of the X-ray rotating anode. Geometric changes of the X-ray rotating anode (for example, this can be determined by three-dimensional measurement of the X-ray rotating anode, and in particular by tactile means using a scanner that scans the external dimensions of the X-ray rotating anode), Individual information determined for each X-ray rotating anode that was analyzed, Type-specific information for each X-ray rotating anode analyzed, For each X-ray rotating anode analyzed, the individual usage data detected, and, The individual history of each X-ray rotating anode that was analyzed, It is configured to include at least one of the following. Including at least one of these additional pieces of information improves the quality of the evaluation of subsequent usage options. For example, strong non-uniformity in the three-dimensional height profile along the circumferential direction can lead to the need for localized repairs. In the case of geometric changes, the resulting rotational imbalance, increase in outer diameter, and / or enlargement of the central mounting hole (in the case of X-ray rotating anodes without an integrally formed stem) are particularly important. From this, in particular, the need for mechanical rework, or measures to recycle the X-ray rotating anode if the extent of the problem is too advanced, can be derived. Based on this, the remaining service life of the X-ray rotating anode can also be estimated. This leads to improved overall lifecycle management of the X-ray rotating anode. From these detected data, further measures to improve future manufactured X-ray rotating anodes can be derived, such as design adjustments, optimization of connection techniques (e.g., soldering, welding, etc.), and / or coating application.

[0032] In essence, the present invention relates to an X-ray rotating anode analysis system and does not include each X-ray rotating anode to be analyzed. According to a further embodiment, the X-ray rotating anode (to be analyzed) is housed as a separate component within a positioning device. This corresponds to the usage configuration of the X-ray rotating anode analysis system. In particular, the positioning device is configured to precisely position the X-ray rotating anode relative to an imaging unit. This is most easily achieved using a corresponding (preferably adjustable) stopper. It is preferable that the positioning device allows the X-ray rotating anode to be positioned (particularly using a correspondingly provided fixing element) in at least two spatial directions (e.g., two spatial directions perpendicular to the axis of rotation), and especially in all three spatial directions, by at least a fitted coupling, and more preferably by an additional friction coupling. Furthermore, it is preferable that the positioning device allows the X-ray rotating anode to be rotated by a certain (preferably adjustable) angle around the axis of rotation after the initial fixing, for example, to inspect different sections of the focal trajectory.

[0033] The present invention further relates to a method for analyzing a spent X-ray rotating anode having a circumferential focal orbit on its surface section, the method comprising the following steps: The steps include positioning the X-ray rotating anode as a separate component relative to the image acquisition unit using a positioning device, The steps include: obtaining a three-dimensional height profile of the surface section of the X-ray rotating anode in the region of the focal orbit using an image acquisition unit and a data processing unit coupled to the image acquisition unit; The steps include: automatically determining the predicted radiation output or characteristic value of the X-ray rotating anode using a data processing unit based on the acquired 3D height profile or a portion thereof; Includes. The steps of acquiring a three-dimensional height profile and automatically determining the predicted radiation output are performed in particular according to (at least) one algorithm, which can be performed by one or more appropriately configured software modules. That is, both of these steps are supported and performed by software. In this case, at least one software module is stored in or in separate memory within the data processing unit so that it can be loaded into and executed on the data processing unit. The method according to the present invention achieves essentially the same advantages as those achieved by the X-ray rotating anode analysis system according to the present invention. Furthermore, the further developments and variations described above are possible in appropriate ways, in which case the features described on the side of the apparatus can be performed or executed by the respective units / components mentioned, in particular as corresponding method steps. In particular, the method according to the present invention is performed using the X-ray rotating anode analysis system according to the present invention, in which case one or more of the further developments / variations described above can also be realized.

[0034] Further advantages and functions of the present invention will be revealed in the following description of embodiments with reference to the accompanying drawings. [Brief explanation of the drawing]

[0035] [Figure 1] Schematic diagram of a longitudinal section of an X-ray tube. [Figure 2] Perspective view of an X-ray rotating anode [Figure 3] Perspective view of a cross-section of another X-ray rotating anode [Figure 4] Schematic diagram of the X-ray rotating anode analysis system according to the present invention [Figure 5] Exemplary 3D height profile relative to the focal orbit surface [Figure 6] Illustration of the calculation of the path length of generated X-rays passing through the focal orbit material for a perfectly smooth focal orbit surface. [Figure 7] Illustration of the calculation of the path length of X-rays generated through the focal orbit material for a focal orbit surface having a surface structure. [Figure 8] Three diagrams are shown. The top diagram (Figure 1) shows an exemplary line profile of the used focal orbital surface, the diagram below it (Figure 2) shows the distribution of additional path lengths obtained from Figure 1, and the diagram below that (Figure 3) shows the radiation distribution obtained therefrom. [Modes for carrying out the invention]

[0036] Figure 1 shows a schematic longitudinal section of the X-ray tube 2. It has a glass valve 4 with a vacuum chamber 6, inside which is a cathode 8 with a heating coil 10, which emits electrons 12 when in use (i.e., when current flows). Opposite the cathode 8 is an X-ray rotating anode 14. The X-ray rotating anode 14 has a central mounting hole, to which a shaft 16 is attached using a fixture 17. This shaft 16 connects the X-ray rotating anode 14 to the rotor 18 of an electric motor 20. The electric motor 20 has a stator 22 on the outside of the glass valve. When in use, the electric motor 20 rotates the X-ray rotating anode 14 around a rotation axis 24 in a known manner. Electrons 12 emitted by the cathode 8 are accelerated to the rotating focal orbit 26 of the X-ray rotating anode 14. When electrons hit the focal orbit 26, their kinetic energy is converted into heat, and a smaller proportion into X-rays 28. For example, it can be formed from borosilicate glass, and through an exit window 30 that helps draw X-rays out of the X-ray tube, a portion of the generated X-rays 28 are drawn out in an X-ray emission direction 32 perpendicular to the rotation axis 24. In addition to this, to reduce the proportion of long-wave (soft) X-rays, further filters made of aluminum or copper are generally also used in the X-ray beam path. The drawn-out X-rays are then used in an X-ray apparatus for penetrating objects, for example, for diagnostic imaging in medical X-ray equipment.

[0037] An example of the structure of the X-ray rotating anode 33 is described below based on Figure 2. In its basic form, it is rotationally symmetric with respect to the axis of rotation 36 (also called the axial or z-direction) and has an anode disk 38 with a central mounting hole 39. The anode disk 38 is made of a molybdenum-based material (having ≥50 wt%, especially ≥90 wt%, of molybdenum) or pure molybdenum. On one side of the anode disk 38, the front side, there is a revolving focal orbit 40 having a focal orbit layer made of a tungsten-rhenium alloy (tungsten: 95 wt%; Re: 5 wt%). The revolving region on the focal orbit 40, depicted as multiple points in Figure 2, visualizes the focal orbit 41, i.e., the annular region (focal spot) scanned by the electron beam during the rotation of the X-ray rotating anode 33. Within the region of the focal orbit 40 of the anode disk 38, there is a revolving inclined focal orbit surface 42. This is inclined at an angle of inclination α (in this case, α = 10°) with respect to the principal extending surface 44, which extends perpendicularly to the axis of rotation 36 and extends radially, and which is also referred to here as the xy-plane. The shape of the focal orbital surface 42 corresponds to the side of a frustum of a cone. Locally, the circumferential direction is perpendicular to the radial direction, and the circumferential direction is perpendicular to the axis of rotation 36. The X-ray emission direction 46 generally extends precisely along one of the radial directions, and is therefore inclined at an angle of inclination α (e.g., 10°) with respect to the focal orbital surface 42. In the Cartesian coordinate system used herein, which spans the x, y, and z axes, the y-axis extends along the X-ray emission direction 46 (shown only as an example in Figure 2 and fixed by the position of the exit window in the X-ray tube), the x-axis extends perpendicularly thereto within the principal extending surface 44, and the z-axis extends axially (as schematically shown in Figure 2). On the back side (i.e., the opposite side of the front side), the graphite body 43 is attached to (specifically, soldered to) the anode disk 38.

[0038] Figure 3 shows a further embodiment of the X-ray rotating anode 34, using the same reference numerals for the same or corresponding components / sections as the X-ray rotating anode 33 in Figure 2. Only the differences are described below; for other details, please refer to the diagram description in Figure 2. The X-ray rotating anode 34 in Figure 3 does not have a graphite body. Furthermore, a shank 48 is integrally formed on the back of this X-ray rotating anode, which in the schematic diagram shows a sleeve 50 monolithically formed on the anode disk 38 and a tubular component 52 connected thereto (e.g., by welding). The tubular component 52 may also have additional mechanical connection elements at its distal end for attachment to other components (such as a rotor).

[0039] Figure 4 shows a schematic diagram of the X-ray rotating anode analysis system 54 according to the present invention. This system includes a positioning device 56, an image acquisition unit 58, additional image acquisition units 60 and 62, and a data processing unit 64, which will be described in more detail below. In this case, the positioning device 56 is formed in various structures, particularly for receiving and accurately positioning the X-ray rotating anode, and its structure is in particular a structure with an integrally provided handle or a structure without an integrally provided handle. Here, an exemplary X-ray rotating anode 33, which basically corresponds to the X-ray rotating anode in Figure 2 and therefore uses the same reference numerals, is fixedly mounted on the shaft 66 of the positioning device 56 by its mounting holes 39. This shaft 66 can be rotated via a rotating device 68, which in this example is electrically operated and can be controlled via the data processing unit 64, so that the rotational position of the X-ray rotating anode 33 relative to the image acquisition unit 58 (and additional image acquisition units 60 and 62) can be adjusted. Furthermore, the shaft 66 is attached to a support component 70 via the rotating device 68. Next, the support component 70 is coupled to the (diametrically shown) frame structure 72 of the X-ray rotating anode analysis system 54, thereby enabling precise positioning of the X-ray rotating anode 33 relative to the frame structure 72 (and therefore relative to the imaging units 58, 60, 62).

[0040] Therefore, the image acquisition units 58, 60, and 62 are also connected to the frame structure 72 via beams 74 so that their position and inclination (see joints 76) can be precisely adjusted relative to the frame structure 72 (and thus relative to the X-ray rotating anode 33). The image acquisition unit 58 (and additional image acquisition units 60, 62) are also connected to the data processing unit 64. The image acquisition unit 58 can be controlled via the data processing unit 64 to acquire multiple separate images of the surface section of the X-ray rotating anode 33 to be analyzed, particularly the surface section in the region of the focal orbit 40 of the X-ray rotating anode 33. This image acquisition unit 58 is formed by a high-resolution camera (preferably operating in the optically visible region) with a magnification of 5 to 20 times and a lateral resolution (in the xy plane with respect to the spatial direction defined in Figure 2 and also depicted in Figure 4) of 4 μm or less. In particular, this camera has a lateral resolution of 3.355 μm along the xy plane of the surface section and a resolution of 3.565 μm in the vertical direction of the z direction, and the magnification is set to 10x, in which case the resolution can be increased by increasing the number of individual images. It is preferable that a separate illumination unit is installed, in particular an illumination unit whose position can be variably adjusted (e.g., an LED having "white" light, i.e., preferably covering a spectrum over substantially the visible wavelength range). In addition to this, or instead, this camera has an internally formed illumination unit (e.g., an LED having "white" light, i.e., preferably covering a spectrum over essentially the visible wavelength range). The same preferably applies to additional imaging units 60, 62, in which case these additional imaging units can be designed and positioned so, for example, that imaging unit 60 can capture an image of a larger section (or the entire front side) of the front side of the X-ray rotating anode 33, and / or that imaging unit 62 can capture an image of a larger section (or the entire back side) of the back side of the X-ray rotating anode 33.

[0041] Control of the image acquisition unit 58 and communication with other system components of the X-ray rotating anode analysis system 54, particularly with additional image acquisition units 60, 62, the rotating device 68, and the tactile sensor 84 described later, are performed by the data processing unit 64 via interface 78 (schematically shown in Figure 4). Furthermore, the data processing unit 64 has an input / display unit 80 that allows the user to input information (input of information, triggering actions, etc.) and display corresponding information (results, recommendations, command prompts, etc.), as well as a memory unit 82 that can store and read data via the data processing unit.

[0042] The acquisition of multiple individual images is preferably performed such that the rotating device 68 further rotates the X-ray rotating anode 33 around the rotation axis 36 by a predetermined feed angle (e.g., an angle in the range of 1 to 2° in each case), thereby allowing the image acquisition unit 58 to produce multiple individual images of the surface section of the focal trajectory 40 being analyzed at each of these different angular positions (i.e., multiple overlaps of individual images of multiple surface sections under the imaging range of each image acquisition unit 58). In parallel, additional image acquisition units 60, 62 can also create individual images (at each angular position, or only at selected angular positions). Furthermore, Figure 4 shows a tactile measuring device 84 having a tactile sensor 86, which is mounted on a support 90 with a variably adjustable angular position via an articulation 88 and connected to a frame structure 72. The tactile sensor 84 can tactilely measure the X-ray rotating anode 33 (even during its rotation if necessary), thereby allowing determination of any possible geometric changes in the X-ray rotating anode 33 that may have occurred.

[0043] The following describes an exemplary embodiment for calculating X-ray absorption along the X-ray emission direction, taking into account local absorption effects due to local surface changes, according to the detected three-dimensional height profile, with reference to Figures 5 to 8. Based on this, the characteristic value of the predicted radiant output can then be determined. Supplementary information and literature regarding the simplifications and approaches related to this calculation can be found in Siller, Maximilian, et al. "Geometrical model for calculating the effect of surface morphology on total x-ray output of medical x-ray tubes." Medical Physics 48.4(2021):1546-1556. In order to enable this calculation to be performed automatically, software capable of performing the calculation according to a corresponding algorithm is provided, and this software can be loaded and executed on a data processing unit (e.g., data processing unit 64 shown in Figure 4).

[0044] Figure 5 shows the three-dimensional height profile M of an analyzed surface section, typical of the aged focal orbit of an X-ray rotating anode after use in an X-ray apparatus. heightAn example of (x,y) is shown (based on the coordinate system defined in Figures 2 and 4). Each image point or pixel in the xy plane of this 3D height profile is assigned a corresponding height value, i.e., a z value, which is represented in grayscale. The z range shown here extends from a negative range of -30 μm (shown in black) to 0 μm (shown in gray) and beyond to a positive range of +30 μm (shown in white) (μm: micrometer). Figure 5 also shows typical damage to the focal orbital surface that occurs after prolonged use. In the lower left portion of this profile, two crater-shaped depressions labeled "A" are visible. These are the generation of particles of the focal orbital material. In the right half, a narrow depression extending almost vertically across the central portion of the image is visible, labeled "B". This is a crack in the focal orbital material. Furthermore, in the upper right portion, a bead-like bulge labeled "C" is visible, which is localized melting. Such a three-dimensional height profile, regardless of its specific shape and height distribution, serves as a starting point for calculating X-ray absorption along the X-ray emission direction.

[0045] The concept underlying the calculations in this embodiment is that, for each X-ray emission point (corresponding to the emission depth of X-rays below the focal orbit in the z direction), the absorption of emitted X-rays by the focal orbit material is determined according to the three-dimensional height profile, taking into account local surface changes, and then summed or integrated over all relevant emission points (in this example, the line profile), as long as these X-rays are directed along the X-ray emission direction. The X-ray emission ("output spectrum") emitted in the X-ray emission direction at each emission point is based on the X-ray spectrum (bremsstrahlung emission distribution with multiple characteristic lines) specific to each focal orbit material as a function of the accelerating voltage (in this case, 100 kV). In this case, data and calculation methods for typical accelerating voltages and focal orbit materials are available in the literature (to simplify the problem, pure tungsten can be used instead of tungsten-rhenium alloys with a high tungsten content, due to similar atomic number and density). Furthermore, it should be considered that only individual image points or pixels of the three-dimensional height profile (or, in this example; the line profile derived therefrom) within the focal spot area of ​​the X-ray rotating anode are taken into account, and these are then weighted according to the electron intensity distribution, in which case this is done only in the final step in this calculation model. Here, the calculation of the line profile of the surface section of the focal orbit to be analyzed is performed assuming that electrons are accelerated at an accelerating voltage of 100 kV to this section, which has a typical size and intensity distribution of the focal spot.

[0046] According to this embodiment, the following simplifications / approaches are used. For simplicity, the average generation depth of X-rays d e- The actual distribution of the occurrence depth along the z axis is used, and the latter means multiple occurrence points along the z coordinate that follow a distribution function for each xy coordinate, requiring a sum or integral over these occurrence points. In other words, this simplification means that for each image point or pixel with xy coordinates, there is a depth d below the focal orbit plane in the z coordinate. e-A precise point of origin is assumed to exist. For example, the average depth of origin in tungsten-based focal orbital materials can be found in the literature, depending on the surface voltage applied between the cathode and the X-ray anode. For example, the average depth of origin de- of X-rays in a 1.6 μm tungsten-based material for an accelerating voltage of 100 kV is published in "Calculation of x-ray spectra emerging from an x-ray tube. Part 1. Electron penetration characteristics in x-ray target." Medical Physics 34.6 Part 1(2007):2164-2174 by Poludniowski, Gavin G., and Philip M. Evans. (Further related information: Behling, Rolf. "Modern diagnostic x-ray sources: technology, manufacturing, reliability". CRC Press, 2021, p.71). Regarding the size of the focal spot and the electron intensity distribution, if the focal spot is fixed on the focal orbital surface (e.g., fixed anode), the electron intensity distribution must be based on the impacted surface (x,y coordinates) of the focal spot. However, in the case of an X-ray rotating anode, the linear, and consequently adapted intensity profile (along the X-ray emission direction, i.e., the y-direction) due to the rotation in use can be used as the basis. For example, this can be determined when using an X-ray rotating anode and can often be well approximated by two overlapping sine functions (depending on the cathode type) (often this intensity distribution is formed by ridges with two overlapping "bumps" in the y-direction). Alternatively, electromagnetic interactions can also be simulated for different cathode types as needed. With respect to the three-dimensional height profile, and therefore even for comparing the radiant output emitted from an aged focal orbit with a surface structure with the radiant output emitted from a perfectly smooth focal orbit surface, it is not necessary to observe the detected three-dimensional height profile as a surface and apply an area function (with x and y coordinates) to it (see, for example, the approach taken in the aforementioned publication by Maximilian Siller et al. for a fixed anode). It is sufficient that the radial line profiles of the corresponding three-dimensional height profiles are considered and compared with each other (these point in the X-ray emission direction, i.e., the y-direction, once per revolution during the rotation of the X-ray rotating anode). This is described in the following calculations using a line profile that runs radially along the focal orbital plane, and this line profile is obtained by the third term below. Note that in the following calculations, it is assumed that this radial direction simultaneously points in the X-ray emission direction, i.e., the y-direction. With respect to the radially generated line profiles, due to the rotational symmetry of the X-ray rotating anode, multiple image points / pixels of the detected 3D height profile generally do not exist precisely along their respective radial directions. Therefore, to generate multiple line profiles running in this direction, it is necessary to make a corresponding approximation to the detected surface structure (e.g., by using a fitted height profile running along the detected multiple image points / pixels), and as a result, a corresponding z value (i.e., height) can be obtained for all y coordinates (i.e., radial coordinates) along that line profile. This determination of multiple radially running line profiles is preferably performed with software support, for example, using a fitting function. For simplification, from each generation point of the line profile used as an example, only the radiation output strictly oriented radially, which in this case is considered to be oriented in the X-ray emission direction, i.e., the y-direction, is extracted and determined. The conical radiation emitted in the region surrounding the X-ray emission direction for each generation point is not initially determined. As a result, the radiation emitted precisely in the X-ray emission direction for multiple generation points can then be summed or integrated. This allows for calculations based on multiple line profiles, as will be explained in detail below. Furthermore, it is assumed that the emitted X-rays travel a minimum path length within the focal orbit material, regardless of the generation point along the X-ray emission direction and any surface structures locally present at that point. This minimum path length is selected as part of the path length of locally emitted radiation through the focal orbit material predicted for a smooth surface, depending on the inclination angle (in this case, α = 10°), and is, for example, 5 μm when the predicted path length is 9.07 μm (this is an example for a focal orbit inclination angle α = 10°). This avoids theoretically possible peak values ​​in the locally emitted radiation output from individual generation points, which could lead to localized false information, based on the specific characteristics of the three-dimensional height profile and its resolution (for example, on the sides of surface structures on the focal orbit surface that are steeply inclined in the X-ray emission direction).

[0047] Referring to FIGS. 6, 7 and 8, the following will explain how the absorption by the focal track material for each X-ray generation point is determined according to the three-dimensional height profile considering local surface changes. The upper diagram in FIG. 8 shows an exemplary line profile of the used focal track surface, plotted as the height (unit: millimeter) (refer to "height[mm]" in the figure) over the y direction (unit: millimeter) (refer to "y[mm]" in the figure). This can be obtained, for example, from a section of the three-dimensional height profile shown in FIG. 5 along the X-ray emission direction y. FIGS. 6 and 7 respectively show schematic cross-sections of such line profiles of the focal track surface. First, in FIG. 6, the situation of a completely smooth focal track surface 92 inclined at an inclination angle α = 10° (shown larger in FIGS. 6 and 7 for clarity) with respect to the y direction is shown. Using two exemplary electrons 94, 96 that collide with the focal track surface 92 at two different y coordinates (simplified representation) and penetrate into their respective generation points 98 according to the average generation depth d of the X-rays e- the path length d of the generated X-rays traveling through the focal track material in the X-ray emission direction (y direction) is shown. Regardless of where the electrons appear within the focal spot, the traveling path length can be determined using the following formula. x-ray d x-ray =d e- / tan(α) Equation (1) d e- = 1.6 μm and α = 10°, a constant "theoretical path length" d x-ray = 9.07 μm is obtained. That is, in the case of a completely smooth focal track surface 92, the generated X-rays first travel a constant path length d of 9.07 μm x-ray ​The X-rays are filtered by the focal orbit material over a path length of 9.07 μm and then emitted from the focal orbit surface. These X-rays are then filtered by filter 102 before striking detector 104 (if there are no obstacles or other objects to be transmitted in the radiation path). For example, a filter made of 2.5 mm thick borosilicate glass (e.g., as an exit window) and a 2 mm thick aluminum filter can be used in this calculation model. Regarding filtering by the focal orbit material, filtering with pure tungsten (W) can be used for simplification in the case of a tungsten-rhenium focal orbit (which has a dominant proportion of tungsten), because tungsten (W) and rhenium (Re) differ only slightly in their atomic number and density. The absorption by the focal orbit material (each over a path length of 9.07 μm) and filtering by filter 102 that occur in the case of a perfectly smooth focal orbit surface are called basic filtering.

[0048] In this case, the potential base emission power of the line profile, or y-coordinate, predicted for such a perfectly smooth focal orbital surface, is used as a reference value. In particular, based on the output spectrum described above, the potential base emission power predicted for a single y-coordinate in the X-ray emission direction is first determined by absorption by the focal orbital material over a path length of 9.07 μm and filtering by filter 102. This is done, in particular, with software support (for example, using SpekCalc pro 1.1, software developed for the theoretical approach by Gavin Poludniowski and Phil Evans at the Institute of Cancer Research in London, UK, and for the graphical user interface by Francois deBlois, Guillaume Landry and Frank Verhaegen at Mc Gill University in Montreal, Canada, which is currently available at www.Spekcalc.weebly.com). In this case, the software is preferably configured to first determine the reduction / filtering of the output spectrum for a single y-coordinate of the line profile (wavelength-dependent) (since the intensity of the reduction / filtering depends on the wavelength or energy of the photons), based on which a "potential base spectrum" is obtained (it is "potential" because the electron intensity distribution and size of the focal spot have not yet been considered), whose intensity distribution is reduced relative to the output spectrum (wavelength-dependent). Next, preferably, a "potential base radiant power" is determined for a single y-coordinate. This is obtained from the sum or integral of the radiant powers over various wavelengths of the potential base spectrum obtained after base filtering. Here, starting from a perfectly smooth focal orbital surface, only the "potential" base spectrum and "potential" base radiant power are considered (i.e., the electron intensity distribution and size of the focal spot have not yet been considered), so these are constant over multiple y-coordinates of the line profile and, accordingly, constant in the circumferential direction for different line profiles.

[0049] In contrast, the focal orbital surface in Figure 7 has a surface structure or surface variation 100, such as that which occurs in a spent X-ray rotating anode (otherwise, Figure 7 is constructed similarly to Figure 6, and the same components / parts are denoted by the same reference numerals). According to this calculation model, the actual path length d' (in the y-direction) travels through the focal orbital material. x-ray As shown in Figure 7, this is determined for each of the 98 X-ray generation points, i.e., for each y-coordinate along the y-direction (X-ray emission direction) of the line profile, taking surface changes into account according to the three-dimensional height profile. In this case, this "actual path length" d' is determined. x-ray In some cases, a partial path length may need to be added to determine the X-ray path. This occurs when the X-ray initially leaves the focal orbital plane in the y-direction from the point of origin, but re-enters the focal orbital material (once or multiple times) (e.g., due to local elevation) before finally reaching the free region outside the focal orbital material. This determination and other calculation steps are preferably performed with software support using appropriately configured software (e.g., Matlab R2017b 64bit; currently available at www.Mathworks.com) unless otherwise specified. For this purpose, each line profile (e.g., as shown in the top diagram of Figure 8) is preferably imported into this software. Alternatively, one or more 3D height profiles are imported into this software, and then multiple radially running line profiles are generated according to the simplification / approach section 3 above. Furthermore, the inclination angle (here, α = 10°) and the mean X-ray origin depth (here, d e- Based on (=1.6μm), as shown in Figure 7, for each y coordinate of each line profile, the respective origin point of each line profile (downward in the focal orbit material in the z direction) e- Starting from (which is shifted by only a few points), the actual path length d' is determined by traveling through the focal orbit material in the y direction. x-rayThis must be determined. This is done using this software, for example, by comparing the original line profile (important for the focal orbit plane) with the d-axis downward in the z-direction within the focal orbit material. e- This can be done by comparing it with a line profile that is otherwise identical (important to the generation point) but shifted by only a certain amount, thereby determining the actual path length traveling in the y-direction corresponding to the respective y-coordinate of each line profile. Then, an additional path length distribution f add (y) is the actual path length d' as follows: x-ray (y) to theoretical path length d x-ray It is determined by subtracting [a certain value]. f add (y=d' x-ray (y)-d x-ray Formula (2) If d'(y) <= 5 μm, then f(y) = 5 μm - 9.07 μm = -4.07 μm

[0050] The actual path length d' for the y-coordinate. x-ray (y) is the theoretical path length d x-ray As long as it is changing from this, this results in an actual filtering that is different from the basic filtering described above. Due to surface changes, the theoretical path length d is for most y coordinates. x-ray Compared to the actual path length d' x-ray (y) becomes large (that is, f add (This value is greater than 0). However, unlike this, for some of the multiple y coordinates, the actual path length d' x-ray (y) becomes smaller (that is, f add If (f) is less than 0, then the shortest path length of at least 5 μm is applied according to the simplification / approach item 5 above (see the second line of equation (2)). The second diagram in Figure 8 shows the additional path length f over the y direction (unit: millimeters) (see "y[mm]" in the figure). add (y) (Unit: micrometer or μm) ("f" in the figure) addThe distribution of additional path lengths plotted as (y)[μm] is shown, which specifically occurs for the line profiles shown in the upper part of Figure 8.

[0051] Next, as with a perfectly smooth focal trajectory (preferably with software support, e.g., SpekCalc pro 1.1; see above), the (wavelength-dependent) reduction / filtering of the general output spectrum is first performed at f add It is determined as a function of (the specifics for multiple different y coordinates have not yet been determined), and from this, f add The "potential actual spectrum" is obtained as a function of f, and its intensity distribution is reduced compared to the output spectrum. Then, the "potential actual radiant power" resulting from the sum or integral of the radiant powers over various wavelengths of the potential actual spectrum is f add It is determined as a function of . As a further step (preferably supported by software, e.g., SpekCalc pro 1.1; see above), the ratio of this potential actual radiant output to the potential base radiant output (determined as above) f red ga f add It is formed as a function of . Therefore, this determined ratio f red (f add ) is the additional path length f that the X-rays must travel from the point of origin. add This indicates how much the potential actual emission power of the X-ray generation point changes relative to the potential base emission power of a perfectly smooth focal orbit plane. This determined ratio f red (f add This can be adjusted by a certain function, preferably a double exponential function (i.e., by the sum of two exponential functions). This starts from a minimum value (-4.07 μm in this example) and adds an additional path length f add If the value is negative, it is greater than 1, then it decreases continuously, and f add For values ​​of =0, it reaches exactly 1. Additional path length add If it is a positive value, it is less than 1, and the additional path length f addAs the value of increases, it approaches 0. This feature is also preferably software-supported here (e.g., in Matlab R2017b 64bit, see above) and specifically an additional path length distribution f, as determined for the line profile using equation (2). add Applied to (y), the radiation distribution f over various y coordinates of the line profile is as shown in equation (3) below. emi (y) is obtained. f emi (y=f red (f add (y) Equation (3)

[0052] In this case, this radiation distribution f emi (y) represents the ratio of the potential actual radiant output to the potential base radiant output for several different y-coordinates of the line profile, and this ratio is associated with the negative value f add (that is, d' x-ray (y) <d x-ray For y coordinates with ), the value f is greater than 1 and positive. add (that is, d' x-ray (y>d x-ray ) is less than 1. This means the actual path length d' x-ray The theoretical path length d of each generation point x-ray The larger the ratio of f to the potential base radiant output, the lower the ratio of the potential actual radiant output to the potential base radiant output (i.e., more emitted radiation is absorbed), and vice versa. The third diagram in Figure 8 shows this ratio, i.e., the radiant distribution f over the y direction (unit: millimeters) (see "y[mm]" in the figure). emi (y) (f in the figure) emi (y)[-]」) is plotted as the additional path length f, which is specifically shown in the second diagram in Figure 8. add This is the result of (y).

[0053] Finally, in order to compare quantities other than those designated as "potential," the electron intensity distribution in the y-direction (i.e., along the radial direction) must also be considered. This is because the radiative output generated at each y-coordinate depends on whether electrons collide with this y-coordinate and at what intensity. For this reason, for example, damage to the focal orbital surface in the radial direction outside the focal spot region is not very significant because no X-rays are generated at these locations, but damage in regions of high electron intensity can be particularly significant, especially if it causes strong shadowing. As explained in Section 2 of the simplification / approach above, the electron intensity distribution at an X-ray rotating anode is a linear intensity profile f (running in the y-direction or radial direction). e- It can be described by (y). Radiation distribution f emi (y) is this intensity profile f e- (y) should be weighted accordingly, as shown in the following equation, and as a result, the ratio O(y) of the "actual radiated output" to the "base radiated output" at each y-coordinate is obtained. O(y)=f e- (y)*f emi (y) Equation (4)

[0054] Next, the ratio O of the actual radiant output emitted over the entire line profile of a damaged focal orbital surface with surface structure to the corresponding base radiant output that would be emitted over the entire line profile in the case of a perfectly smooth focal orbital surface. Linie To obtain this, O(y) must be integrated over the y-coordinate, as shown by the following equation. O Linie =∫f e- (y)*f emi (y)dy Equation (5)

[0055] In this way, the effect of surface structures occurring in the region of the specifically analyzed line profile of the damaged focal orbital surface on the emitted radiant power can be evaluated. In particular, O LinieThis is an indicator of the attenuation of radiant power due to damage to the focal orbit surface. Furthermore, naturally, numerous line profiles (each running radially and preferably distributed circumferentially around the X-ray rotating anode) can be evaluated in a similar manner. In this case, on the one hand, it is possible to determine the variations that may occur circumferentially around the X-ray rotating anode. Furthermore, the total radiant power obtained for each line profile is used to determine the O Linie It can also be determined by summing / integrating the values.

[0056] The present invention is not limited to the embodiments described. For example, as an alternative to the simplification / approach in Section 2 (see above) concerning the focal spot and line profile, the electron intensity distribution over the region, i.e., the function f e- (x,y) can also be used. Next, depending on the size of the focal spot, a number of adjacent line profiles of the 3D height profile can be incorporated, and finally, the resulting emissivity distribution f emi (x,y) represents the electron intensity distribution f e- It is weighted by scalar multiplication with (x,y). Then, several such surface sections in the circumferential direction of the focal orbit are analyzed in the same manner.

Claims

1. An X-ray rotating anode analysis system for analyzing a spent X-ray rotating anode (14;33;34) having a focal orbit (26;40) orbiting a surface section, wherein the focal orbit (26;40) comprises a focal orbit plane (42) that is curved and inclined with respect to a principal extending plane (44) perpendicular to the axis of rotation (36), A positioning device (56) for the X-ray rotating anode (14;33;34), Image acquisition unit (58), A data processing unit (64) coupled to the image acquisition unit (58), Equipped with, The positioning device (56) and the image acquisition unit (58) are configured such that the X-ray rotating anode (14;33;34) is positioned as a separate component relative to the image acquisition unit (58), and the positioning device (56) is configured to enable positioning of the X-ray rotating anode (14;33;34) in at least two spatial directions, and to enable rotation of the X-ray rotating anode (14;33;34) by an adjustable predetermined rotation angle around the rotation axis (36) after the first positioning. The image acquisition unit (58) and the data processing unit (64) are configured to detect the three-dimensional height profile of the surface section of the X-ray rotating anode (14;33;34) in the region of the focal trajectory (26;40) by the image acquisition unit (58) and the data processing unit (64). The data processing unit (64) is configured to determine the predicted radiation output or characteristic value of the X-ray rotating anode (14;33;34) from the detected three-dimensional height profile or a portion thereof. X-ray rotating anode analysis system.

2. The image acquisition unit (58) and the data processing unit (64) The system is configured to use electromagnetic radiation to create multiple separate images, each having different depth information for the surface sections of the X-ray rotating anode (14;33;34) being analyzed. The data processing unit (64) is configured to reconstruct a three-dimensional height profile of the surface section to be analyzed from the individual images. The X-ray rotating anode analysis system according to claim 1.

3. The X-ray rotating anode analysis system according to claim 2, wherein the image acquisition unit (58) and the data processing unit (64) are configured to use electromagnetic radiation in the wavelength range of 380 nm to 780 nm to produce a plurality of separate images of the surface section to be analyzed from different angles.

4. The X-ray rotating anode analysis system according to claim 1, wherein the data processing unit (64) is configured to determine the predicted radiant output or characteristic value of the X-ray rotating anode (14;33;34) based on the automatically calculated absorption of X-rays along the X-ray emission direction (32;46) according to the detected three-dimensional height profile, taking into account local absorption effects due to local surface changes (100).

5. The X-ray rotating anode analysis system according to claim 4, wherein the data processing unit (64) is configured to extend in the X-ray emission direction (32, 46) over a predetermined minimum length along the detected surface section of the X-ray rotating anode (14, 33, 34) and to have at least one line profile having local surface changes according to the three-dimensional height profile, which can be used for automatic calculation of X-ray absorption.

6. The data processing unit (64) is configured to use at least one surface profile to automatically calculate the X-ray absorption. The surface profile is along the detected surface section, extends along the X-ray emission direction (32;46) over a predetermined minimum length, and extends over a predetermined minimum width substantially perpendicular to this X-ray emission direction (32;46), and has local surface variations according to the three-dimensional height profile. The X-ray rotating anode analysis system according to claim 4.

7. The data processing unit (64) processes the following input values, namely: X-ray emission depth, X-ray emission angle (α), The material of the focal orbits (26;40) of the X-ray rotating anode (14;33;34), Size of the focus spot, The electron intensity distribution of the aforementioned focal spot, and Filter (102), The X-ray rotating anode analysis system according to claim 4, wherein at least one of the following is configured to be included in the automatic calculation of X-ray absorption.

8. The X-ray rotating anode analysis system according to claim 1, wherein the data processing unit (64) is configured to identify and classify damage (A, B, C) in the region of the surface section of the focal trajectory (26;40) of the X-ray rotating anode (14;33;34) from a detected three-dimensional height profile of the surface section of the focal trajectory (26;40) or from a plurality of image information detected by other means.

9. The X-ray rotating anode analysis system according to claim 1, wherein the image acquisition units (58, 60, 62) and the data processing unit (64) are configured to enable the image acquisition units (58, 60, 62) and the data processing unit (64) to detect at least one image of another surface section in a region adjacent to the focal orbit (26; 40) of the X-ray rotating anode (14; 33; 34).

10. The X-ray rotating anode analysis system according to claim 1, wherein the data processing unit (64) is configured to evaluate a plurality of subsequent usage options for the X-ray rotating anode (14;33;34) based on the determined predicted radiation output or based on characteristic values, and to issue corresponding usage recommendations.

11. The data processing unit (64) is coupled to the memory unit (82), and the data processing unit (64) and the memory unit (82) interact as follows: The individual information determined for each of the analyzed X-ray rotating anodes (14; 33; 34) can be stored in the memory unit (82) by the data processing unit (64) and read from the memory unit (82). Type-specific information for multiple different types of X-ray rotating anodes (14; 33; 34) can be stored in the memory unit (82) by the data processing unit (64) and read from the memory unit (82). The usage data obtained for each of the analyzed X-ray rotating anodes (14; 33; 34) can be stored in the memory unit (82) by the data processing unit (64) and read from the memory unit (82). Individual histories regarding the on-site use of each of the analyzed X-ray rotating anodes (14;33;34), as well as subsequent processing and repairs, can be stored in the memory unit (82) and read from the memory unit (82). The X-ray rotating anode analysis system according to claim 1, configured for at least one of the following.

12. The data processing unit (64) evaluates the next usage options for the X-ray rotating anode (14;33;34) by obtaining the following further information, namely: Uniformity of the three-dimensional height profile along the circumferential direction of the X-ray rotating anode (14;33;34), Damage to the focal trajectories (26;40) of the X-ray rotating anode (14;33;34) in the surface section region (A, B, C), Further detailed images of the surface section in the region adjacent to the focal orbits (26;40) of the aforementioned X-ray rotating anode (14;33;34), Geometric changes of the aforementioned X-ray rotating anode (14;33;34), Information determined individually for each of the analyzed X-ray rotating anodes (14;33;34), Information specific to each type of the analyzed X-ray rotating anode (14;33;34), The individual usage data for each of the analyzed X-ray rotating anodes (14; 33; 34), and, The individual histories of the X-ray rotating anodes (14;33;34) analyzed above, The X-ray rotating anode analysis system according to claim 10, configured to include at least one of the following.

13. The X-ray rotating anode analysis system according to claim 1, wherein the X-ray rotating anode (14; 33; 34) is housed as an individual component within the positioning device (56).

14. A method for analyzing a spent X-ray rotating anode (14;33;34) having a focal orbit (26;40) orbiting a surface section, wherein the focal orbit (26;40) comprises a focal orbit plane (42) that is curved and inclined with respect to a principal extending plane (44) perpendicular to the axis of rotation (36), and the method comprises the following steps: A positioning device (56) that enables the X-ray rotating anode (14;33;34) to be positioned in at least two spatial directions and, after the first positioning, to be rotated by a predetermined adjustable rotation angle around the rotation axis (36), is used to position the X-ray rotating anode (14;33;34) as an individual component relative to the image acquisition unit (58); The steps include: obtaining a three-dimensional height profile of a surface section in the region of the focal orbit (26;40) of the X-ray rotating anode (14;33;34) using the image acquisition unit (58) and a data processing unit (64) coupled to the image acquisition unit (58); The data processing unit (64) automatically determines the predicted radiation output or characteristic value of the X-ray rotating anode (14;33;34) from the acquired three-dimensional height profile or a portion thereof. A method that includes this.

15. The method according to claim 14, carried out using the X-ray rotating anode analysis system (54) described in any one of claims 1 to 13.

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