Stable top bridge fabrication for DAX gratings

Abstract

To improve the mechanical stability of X-ray gratings with top bridges for X-ray dark-field and / or X-ray phase-contrast imaging, a change in the manufacturing process is proposed to reduce or prevent undesirably high stresses on the top bridges. Specifically, it is proposed to electroplate the top bridges after bending. In other words, the electroplating of the top bridges is performed on the curved geometry.

Description

Technical Field

[0001] The present invention relates to a method for producing an X-ray grating for an imaging device used for X-ray dark-field imaging and / or X-ray phase-contrast imaging. The present invention also relates to a microstructure produced by the method, an imaging device, and a method for performing X-ray phase-contrast and / or dark-field imaging. Background Art

[0002] Grating-based phase contrast and dark-field X-ray (DAX) imaging are promising technologies for enhancing the diagnostic quality of X-ray equipment, for example in the fields of mammography, chest radiography, and computed tomography (CT). One of the most challenging issues in building clinical systems based on this technology is the fabrication of the gratings. Specifically, the source grating G0 and the absorption grating G2 may require a grating structure with a pitch of approximately several to tens of μm at a gold height exceeding 200 μm in order to achieve sufficient attenuation across the entire spectrum of the X-ray tube, especially when the tube provides photons in the energy range above 30 to 40 keV.

[0003] Polymer structures (resist structures) manufactured by photolithography can be used for grating fabrication by filling the polymer template with a strongly X-ray absorbing material (e.g., gold). If a grating is used as the source grating G0, it has been observed that the resist cannot withstand the thermal and radiation loads and the entire grating becomes unstable. Therefore, it is planned to strip the resist after electroplating. In order to ensure the mechanical stability of the grating sheets, they need to be connected by electroplating an additional bridge on top of the grating. In order to access the full field of view, the source grating G0 needs to be bent. However, the bent top bridge can experience high mechanical stress. Summary of the Invention

[0004] There may be a need to improve the mechanical stability of an X-ray grating having a top bridge for use in X-ray dark field imaging and / or X-ray phase contrast imaging.

[0005] The objects of the invention are solved by the subject-matter of the independent claims, wherein further embodiments are incorporated in the dependent claims. It should be noted that the aspects of the invention described below also apply to the method for generating an X-ray grating, the microstructure, the imaging device, the method for performing X-ray phase contrast and / or dark field imaging.

[0006] A first aspect of the present invention provides a method for generating an X-ray grating for an imaging device used for X-ray dark field imaging and / or X-ray phase contrast imaging. The method comprises the following steps:

[0007] a) generating a resist negative grating having a plurality of periodically arranged grating grids and grating openings on a flat sample;

[0008] b) filling the grating openings on the flat sample by electroplating by the following operation: continuing the electroplating up to the height of the grating web to form a grating sheet;

[0009] c) processing a window on top of the resist negative grating, said window enabling the introduction of a top bridge substantially perpendicular to the grating web;

[0010] d) bending the resist negative grating to a desired radius; and

[0011] e) Filling the window by electroplating to form the top bridge after bending the resist negative grating.

[0012] In other words, it is proposed to reduce or prevent the undesirably high stress on the top bridge by means of a change in the manufacturing process. Specifically, it is proposed to electroplate the top bridge after bending. In other words, the electroplating of the top bridge is performed on the curved geometry. The detailed manufacturing process will be described later and specifically with reference to Figure 1 and Figures 2A to 2G Exemplary embodiments are explained in

[0047]

[0013] It will be appreciated that the above operations may be performed in any suitable order (eg, serially, simultaneously, or a combination thereof), subject where applicable to a necessary specific order, eg, bending before the top bridge is plated.

[0014] For example, it is possible to swap steps b) and c). The process will be as follows:

[0015] a1) generating a resist negative grating having a plurality of periodically arranged grating grids and grating openings on a flat sample, i.e., step a);

[0016] b1) processing a window on top of the resist negative grating, said window enabling the introduction of a top bridge substantially perpendicular to the grating web, i.e. step c);

[0017] c1) filling the grating openings on the flat sample by electroplating, by the following operation: continuing the electroplating until the height of the grating web to form a grating sheet, i.e., step b);

[0018] d1) bending the resist negative grating to a desired radius, i.e., step d); and

[0019] e1) Filling the window by electroplating to form the top bridge after bending the resist negative grating, step e).

[0020] It should also be noted that some steps can be performed simultaneously. For example, it is possible to make the top bridge window directly after making the resist negative grating and to electroplate both the grating opening and the top bridge window in one step. The process would be as follows:

[0021] a2) generating a resist negative grating having a plurality of periodically arranged grating grids and grating openings on a flat sample, i.e., step a);

[0022] b2) processing a window on top of the resist negative grating, said window enabling the introduction of a top bridge substantially perpendicular to the grating web, i.e. step c);

[0023] c2) bending the resist negative grating to a desired radius, i.e., step d);

[0024] d2) In one step, the grating openings on the flat sample are filled by electroplating to form a grating sheet, and the window is filled by continuing the electroplating to form the top bridge, ie steps b) and e).

[0025] According to an embodiment of the present invention, the method further comprises the step of removing the resist negative grating between the grating flakes after performing the electroplating.

[0026] According to an embodiment of the present invention, in step d), a frame is provided which allows the resist negative grating to be precisely bent to the desired radius.

[0027] Since the plating of the top bridge must be done in a curved geometry, it may be beneficial to have a frame, for example for the G0 structure, that allows precise bending to the final radius and is compatible with the mounting position close to the X-ray tube in the imaging device.

[0028] According to an embodiment of the present invention, the bending radius of the frame is compatible with a mounting position close to an X-ray tube in the imaging device.

[0029] According to an embodiment of the present invention, the frame is made of a non-conductive material, or the frame is completely covered by a non-conductive material.

[0030] Since the plating after bending must be limited to the area of ​​the top bridge and not on other surfaces of the frame, special materials such as non-conductive materials or non-conductively coated frames can be used and some protection must be made to the areas where no plating should be applied. Examples of non-conductive materials may include plastic, glass, ceramic, etc.

[0031] According to an embodiment of the present invention, step e) further comprises selecting a temperature for the electroplating, wherein the selected temperature is selected so that geometric changes and / or mechanical stresses of the X-ray grating are minimal or nearly minimal under operating conditions of the X-ray grating in the imaging device.

[0032] X-ray gratings such as G0 are typically used in a holder close to the X-ray tube (at the X-ray window). The X-ray tube will be operated under different conditions and will be heated, for example, from room temperature to about 70°C. On the other hand, there are transport conditions with a wider temperature range. Temperature variations (transport - static, operation - slow dynamic) should have a minimal effect on the deformation of the grating and the stabilization bridge, so that the expansion of the bridge should not ideally cause the foil to bend. For example, it may be preferable to use a nominally "0" deformation and then at a temperature of 40°C to have a limited bending with only a + / - 20°C variation, so that the effect on the bending and therefore on the X-ray beam formation will be minimized.

[0033] Similar to vibrations of the X-ray tube during operation, it may be desirable to avoid resonant frequencies in the bridge and grating that would be within the range of the anode rotation frequency during operation.

[0034] For electroplating, the temperature must be selected to allow for good electroplating conditions. However, a temperature that allows for good electroplating conditions may not be suitable for achieving the desired mechanical properties of the top bridge, as the properties of the plated top bridge also depend on the temperature used for electroplating. Therefore, an overall trade-off can be made between allowing for good electroplating conditions and addressing the expected stress conditions.

[0035] The influence of the electroplating process conditions on the thermal and mechanical properties of, for example, the electroplated top bridge (such as residual stress, elastic modulus, thermal expansion, etc.) can be simulated and studied by, for example, finite element analysis. The influence of the electroplating process conditions on the thermal and mechanical properties of the electroplated top bridge can also be studied based on experimental results. Based on the properties of the electroplated top bridge and its relationship to the process conditions, it is possible to select a temperature for electroplating to achieve the desired properties of the electroplated top bridge (such as thermal and mechanical properties) to address the expected stress conditions. In other words, for the overall mechanical design of the curved structure, a complete design of the X-ray grating may be required so that the geometric structure changes and mechanical stresses caused by temperature changes and / or mechanical vibrations are minimal or close to minimal under the operating conditions of the X-ray grating in the imaging device.

[0036] In an example, the temperature used for electroplating may be selected to produce an X-ray grating having a limited bend or other variation of only + / - 5°, + / - 10°, + / - 20° at a temperature of 40°C.

[0037] In an example, the temperature for electroplating may be defined so that for the fabricated X-ray grating, the resonant frequencies in the bridge and grating are not within the range of the anode rotation frequency during operation.

[0038] In an example, the temperature used for electroplating can be selected to produce an X-ray grating having limited bending or other variation of only + / - 5°, + / - 10°, + / - 20° at a temperature of 40°C, and the resonant frequencies in the bridge and grating are not within the range of the anode rotation frequency during operation.

[0039] According to an embodiment of the invention, the top bridge is shaped such that mechanical stresses due to the top bridge are minimal or close to minimal under operating conditions of the X-ray grid in the imaging device.

[0040] In other words, the choice of the shape of the top bridge can have an impact on the stress generated. Therefore, for the overall mechanical design of the curved structure, it may be desirable to optimize the shape design of the top structure to minimize the impact on geometric changes and mechanical stresses due to temperature changes and mechanical vibrations during operation of the imaging system.

[0041] The top bridge shape can be modified using thickness variations and bridge profile optimization to accommodate temperature expansion while minimizing sheet deformation, depending on the stiffness of the bridge design. A slightly curved bridge, like a spring, can minimize stress at the interface with the sheet compared to a zero-tolerance distance. The shape can be adjusted based on, for example, tube temperature variations, system vibrations, and gravity during tube positioning to reduce mechanical stresses under operating conditions of the X-ray grid in the imaging device.

[0042] According to an embodiment of the present invention, the top bridge and the grating sheet are made of the same material.

[0043] For material compatibility, it may make sense to also make the bridge from the same material. Thus, a strongly X-ray absorbing material (such as gold) may be used for both the top bridge and the grating foil.

[0044] According to an embodiment of the present invention, the grating sheet is electroplated with a high X-ray absorption material, and the top bridge is electroplated with a low X-ray absorption material.

[0045] In other words, the choice of material for the top bridge can also have an impact on the stresses generated. Therefore, the choice of material and geometry for the top bridge is a trade-off between imaging properties for the stabilizing effect of the bridge in curved geometries and mechanical properties. Examples of imaging properties include low absorption in the grooves and top bridge, no bending of the absorbing walls and no vibration of the walls in the same position, and lifetime stability. Examples of mechanical properties include compensation for the effects of temperature, vibration, static and dynamic stresses, thermal expansion, etc. Therefore, for the overall mechanical design of the curved structure, it may be necessary to optimize the choice of material for the top structure to minimize the impact on geometric changes and mechanical stresses caused by temperature changes and mechanical vibrations during operation of the imaging system.

[0046] According to an embodiment of the invention, the resist negative grating comprises a plurality of stabilizing structures for stabilizing the mesh.

[0047] The top bridge can be applied to any type of resist negative grating, including resist negative gratings with, for example, bridge or sunlight-stable structures.

[0048] According to an embodiment of the present invention, the stabilizing structure comprises a bridge structure and / or a sun ray structure.

[0049] According to an embodiment of the present invention, the bending in step d) is a positive bending or a negative bending.

[0050] Another aspect of the invention provides a microstructure produced by the method as described above and below.

[0051] With the proposed manufacturing process, the top bridge of the microstructure is less likely to experience high mechanical stress. This can reduce the risk to the uniformity of the microstructure, as the top bridge is less likely to enter the ductile regime at different bending radii. In other words, the microstructure has improved mechanical stability.

[0052] Another aspect of the present invention provides an imaging device for capturing an image of a subject, comprising:

[0053] - X-ray source;

[0054] - source grating;

[0055] - a diffraction grating for diffracting X-rays emitted from the X-ray source;

[0056] - an absorption grating for absorbing a portion of the X-rays diffracted by the diffraction grating; and

[0057] - a detector for detecting the X-rays that have passed through the absorption grating;

[0058] Therein, at least one of the source grating, the diffraction grating and the absorption grating comprises a microstructure according to any one of the exemplary embodiments and examples described above and below.

[0059] The imaging device can be provided for medical or non-medical applications (e.g., non-destructive testing). The imaging device can employ a fixed geometry, such as a planar X-ray and / or a rotational CT-type system. Due to the improved mechanical stability of the microstructure, the phase information detected by the imaging system is less susceptible to temperature changes and mechanical vibrations during operation of the imaging device.

[0060] Another aspect of the present invention provides a method of performing X-ray phase contrast and / or dark field imaging, comprising:

[0061] - positioning the object between the source grating and the diffraction grating or between the diffraction grating and the absorption grating of an imaging device according to any of the exemplary embodiments and examples described above and below;

[0062] - emitting an X-ray beam onto the object; and

[0063] - detecting the X-ray beam having passed through the object, the source grating, the diffraction grating and the absorption grating of the imaging device for acquiring image data.

[0064] As used herein, the term "substantially" refers to the complete or nearly complete extent or degree of the condition as indicated. For example, a reference to the top bridge being substantially perpendicular to the grating web would mean that the top bridge is substantially perpendicular to perform a specific function, namely, to provide additional mechanical stability. The precise permissible degree of deviation from absolute perfection may depend on the desired mechanical stability and manufacturing tolerances. For example, a deviation of ±5° from absolute perfection may be considered to be substantially perpendicular. In some cases, for example, when high mechanical stability is desired, a deviation of ±0.1° from absolute perfection may be considered to be substantially perpendicular.

[0065] Furthermore, in this context the term "close to" the minimum value means preferably 10% from the minimum value, more preferably 5% from the minimum value, even more preferably 1% from the minimum value, and most preferably 0% from the minimum value.

[0066] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described by way of example in the following description and with reference to the accompanying drawings, in which:

[0068] Figure 1A flow chart of a method for generating an X-ray grating of an imaging device for X-ray dark field imaging and / or X-ray phase contrast imaging is shown.

[0069] Figures 2A-2G A method for generating an X-ray grating according to an exemplary embodiment of the present disclosure is shown.

[0070] Figure 3 An example of the structure of an imaging device is shown.

[0071] Figure 4 A flow chart of a method for performing X-ray phase contrast and / or dark field imaging is shown.

[0072] It should be noted that the drawings are purely diagrammatic and not drawn to scale. In the drawings, elements corresponding to elements already described may have the same reference numerals. Regardless of whether or not indicated as non-limiting, examples, embodiments, or optional features should not be construed as limiting the invention as claimed. DETAILED DESCRIPTION

[0073] As mentioned above, if a grating is used as the source grating G0, it was observed that the resist cannot withstand the thermal and radiation loads, and the entire grating becomes unstable. Therefore, it was planned to strip the resist after electroplating in order to ensure the mechanical stability of the grating sheet by electroplating an additional bridge on top of the grating. In fact, simulations using the finite element method (FEM) showed that for small bending radii, there is even a risk that the material in the top bridge leaves the elastic domain and enters the ductile domain. This is particularly risky for the uniformity of the grating, because there will always be variations in the thickness of the bridge, which implies that the bridge will enter the ductile domain at different bending radii. In addition, there are stresses due to the top bridge, which lead to unacceptable tilting of the grating sheet.

[0074] In order to enhance the mechanical stability of the fabricated X-ray grating, Figure 1 A flow chart of a method 100 for generating an X-ray grating for an imaging device for use in X-ray dark field imaging and / or X-ray phase contrast imaging is shown. Figures 2A-2G The exemplary embodiment in describes the following steps.

[0075] In step 110 (ie, step a)), a resist negative grating having a plurality of periodically arranged grating grids and grating openings is produced on a flat sample. Figure 2A A perspective view of an example of a resist negative grating 10 is illustrated, and Figure 2BThe figure shows a front view of a resist negative grating 10 in the XZ plane. The resist negative grating 10 has a plurality of periodically arranged grating meshes 12 and grating openings 14 on a flat sample 16 such as a silicon substrate. The grating mesh 12 can also be called a resist sheet. The grating mesh 12 forms a resist structure, which can be a polymer structure. The shape, size and / or pattern of the periodically arranged grating mesh 12 is determined based on the structure of the desired X-ray grating. Figure 2A In the example of the resist negative grating 10, the resist structure for making a one-dimensional grating is provided. In another example (not shown), the pattern can be composed of a periodic structure of a square pattern, the period of which can be about 1 μm to 10 μm, and the height of which can be about more than 200 μm. The resist negative grating 10 can also have a stabilizing structure for stabilizing the resist (not shown). One example of a stabilizing structure is a bridge structure. Another example of a stabilizing structure is a sunray structure.

[0076] In step 120 (i.e., step b)), the grating openings on the flat sample are filled by electroplating, and the electroplating is continued until the height of the grating mesh to form a grating sheet. Figure 2C As illustrated in FIG, the grating flakes 18 (i.e., metal microstructures) are formed by electrolytically plating the grating openings 14 of the resist negative grating 10 with metal from the surface 20 of the flat sample 16 while using the resist negative grating 10 as a mold. As a result, fine metal microstructures can be produced within the grating openings 14 (i.e., recessed portions) of the resist negative grating 10. The metal can be embodied by an X-ray absorbing metal (such as silver or molybdenum, preferably with a high absorption coefficient, such as lead, bismuth, or tungsten). Preferably, the X-ray absorbing metal is also formed by electrolytic plating to achieve microstructure formation. However, the plating capabilities of different materials vary considerably. Therefore, metal selection can be a trade-off between X-ray absorbing capability and plating capability.

[0077] In step 130 (i.e. step c)), a window is processed on top of the resist negative grating. This window enables the introduction of a top bridge that is substantially perpendicular to the grating web. For example, Figure 2D A side view of the resist negative grating 10 in the YZ plane is shown. A window 26 is processed on top 22 of the resist negative grating 10. The window 26 can have one or more small grooves or openings that take the shape of a rectangle with the width of the top bridge or any other suitable shape. This can be processed with a laser. Another option can be a combination of masking and specific etching. The window can also be processed to achieve optimized functions for mechanical stability and a clean interface to allow electroplating of the interface of the existing grating web 12 to the top bridge. Once the window 26 is created, the grating sheet 18 is connected through the grooves or openings (which can be filled to form the top bridge).

[0078] In step 140 (i.e., step d), the resist negative grating is bent to a desired radius. Figure 2E An example of a curved resist negative grating 10 is illustrated in FIG. Figure 2E Again, a front view of the resist negative grating 10 in the XZ plane is shown. It should also be noted that the curvature can be positive (not shown), i.e. the upper side of the resist negative grating is compressed and the lower side is stretched; or negative, i.e. the upper side of the resist negative grating is stretched and the lower side is compressed, as shown in FIG. Figure 2E As shown in the figure.

[0079] In step 150 (ie step e)), after bending the resist negative grating, the window is filled by electroplating to form a top bridge after bending the resist negative grating. Figure 2F A side view of the resist negative grating in the YZ plane is now illustrated. A top bridge 24 is formed on the top 22 of the resist negative grating 10. Since the electroplating of the top bridge 24 must be done in a curved geometric structure, the GO structure may require a frame (not shown) that, on the one hand, allows precise bending to the final radius and is compatible with the mounting position close to the X-ray tube in the imaging device. On the other hand, the electroplating after the bend must be limited to the area of ​​the top bridge and not on other surfaces of the frame. Special materials such as non-conductive materials (such as plastic, glass or ceramic) can be used to protect areas where no electroplating should be applied. Alternatively, a non-conductive coating frame can be used to protect areas where no electroplating should be applied. In other words, the exposed surface is limited to the area of ​​the top bridge on the top 22 of the resist negative grating 10, and the rest of the back surface including the resist negative grating can all be covered with non-conductive material or with a non-conductive coating frame. Therefore, in electrolytic plating, metal can be deposited only from the exposed surface (i.e., the area of ​​the top bridge).

[0080] As an option, the resist negative grating 10 between the grating flakes 18 may be removed after the electroplating has been performed, ie after step 150 .

[0081] Figure 2G An example of an X-ray grating 30 produced by the method described above and below is shown after stripping the resist. Figure 2G, while the desired bending direction would be inwards. A plurality of top bridges 24 are introduced on top of the grating sheet 18. The top bridges 24 are substantially perpendicular to the grating sheet 18 to ensure mechanical stability. The shape, size and pattern of the top bridges 24 are determined based on the desired mechanical stability to be achieved under the operating conditions of the X-ray grating in the imaging device. As previously mentioned, the top bridges can have a shape suitable for reducing the mechanical stresses under the operating conditions of the X-ray grating in the imaging device. The material of the top bridges can also be selected to have an influence on the stresses generated. FEM simulations can be helpful in finding the desired shape and / or material of the top bridges.

[0082] In this way, undesirably high stresses on the top bridge can be prevented by changes in the manufacturing process, particularly by electroplating the top bridge after bending. The microstructure produced by this method exhibits less stress on the top bridge. Consequently, for large bending radii, there is less risk of the material in the top bridge leaving the elastic domain and entering the ductile domain. This can be particularly beneficial for grating uniformity, as variations in the thickness of the top bridge are always present. In other words, the uniformity of the microstructure is less susceptible to temperature changes and mechanical vibrations during operation of the imaging system. Consequently, the mechanical stability of the microstructure is improved.

[0083] It will be appreciated that the above operations may be performed in any suitable order (eg, serially, simultaneously, or a combination thereof), subject where applicable to a necessary specific order, eg, bending before the top bridge is plated.

[0084] Therefore, it is possible to swap some of the process steps. For example, it is possible to swap steps b) and c). The process would be as follows: a) → c) → b) → d) → e). In another example, it is also possible to bend the resist negative grating even earlier, that is, to perform the electroplating of the grating sheet after the bending. The process would be as follows: a) → c) → d) → a combination of b) and e). In other words, the basic idea is still to bend the resist negative grating before the top bridge is electroplated.

[0085] Additional methods can be used to optimize the mechanical stability of the top bridge under the operating conditions of X-ray imaging.

[0086] As an example, typically, for electroplating, the temperature must be selected to allow good electroplating conditions. However, the temperature for the electroplating in step 150 can be selected so that the geometric changes and / or mechanical stresses of the X-ray grating are minimal or close to minimal under the operating conditions of the X-ray grating in the imaging device. For example, it can be considered to optimize the complete design of the X-ray grating to have minimal effects on geometric changes and mechanical stresses due to temperature changes and mechanical vibrations under the operating conditions of the X-ray grating in the imaging system. This optimization can be performed based on the properties of the electroplated top bridge and its relationship to the process conditions. For example, the temperature for electroplating can be selected to achieve the desired mechanical properties of the electroplated top bridge for solving the expected stress conditions.

[0087] However, the optimal plating temperature for allowing good plating conditions and the optimal plating temperature for achieving the desired mechanical properties of the plated top bridge may be different. Thus, an overall trade-off may be chosen between allowing good plating conditions and addressing expected stress situations.

[0088] As another example, a particular shape of the top bridge can minimize stresses under such operating conditions and can be prepared, or the top wall interface area can be pre-treated and / or have post-processing, such as temporal variation of plating conditions. The shape (or geometry) of the top bridge can be optimized using thickness variation and bridge profile optimization to allow for temperature expansion but less sheet deformation, depending on the stiffness of the bridge design. A slightly curved bridge like a spring can minimize stresses at the interface to the sheet compared to a zero tolerance distance. The shape can be adjusted based on, for example, the temperature range of the tube, vibrations of the system, gravity during tube positioning, etc. to reduce mechanical stresses under operating conditions of the X-ray grating in the imaging device.

[0089] As another example, grating meshes are often manufactured from highly X-ray absorbing materials, such as gold. For material compatibility, it can make sense to also manufacture the bridge from the same material. This can create problems since the absorption of the top bridge can have an impact on imaging performance. Therefore, it can be beneficial to electroform the top bridge from a less absorbing material, such as nickel, for example. The choice of material for the top bridge can also have an impact on the stresses generated. Therefore, material selection is a trade-off between imaging properties and mechanical properties for a stabilizing effect of the bridge in curved geometries.

[0090] In the following, reference will be made to Figure 3 An imaging apparatus utilizing X-ray Talbot interferometry is described. Figure 3 The configuration of an imaging device 200 using the microstructure manufactured in the above-described exemplary embodiments or examples as any one of the source grating G0 , the diffraction grating G1 , and the absorption grating G2 is schematically illustrated.

[0091] The imaging device 200 according to this exemplary embodiment includes an X-ray source 210 for emitting spatially coherent X-rays using a source grating G0, a diffraction grating G1 for periodically modulating the phase of the X-rays, an absorption grating G2 on which an X-ray absorbing portion (shielding portion) and an emitting portion are arranged, and a detector 220 for detecting the X-rays. Any of the source grating G0, the diffraction grating G1, and the absorption grating G2 may include a microstructure manufactured by the exemplary embodiments or examples described above. Preferably, at least the source grating G0 includes a microstructure that can improve the mechanical stability of the source grating G0 and, therefore, the image quality.

[0092] The imaging device may be a medical or non-medical imaging device. The imaging device may be a fixed geometry planar X-ray and / or a rotating CT system.

[0093] As previously discussed, the uniformity of the microstructure is less susceptible to temperature changes and mechanical vibrations during operation of the imaging device. Consequently, the phase information detected by the imaging device is less susceptible to temperature changes and mechanical vibrations during operation of the imaging device. In other words, the uncertainty of phase detection during operation of the imaging device can be reduced, and image quality can be improved.

[0094] Figure 4 A flow chart of a method 300 for performing X-ray phase contrast and / or dark field imaging is shown. Figure 4 The following steps are described with reference to the exemplary imaging apparatus 200 in FIG.

[0095] In step 310, the object 50 is positioned between the source grating GO and the diffraction grating Gl Alternatively, the object 50 may be positioned between the diffraction grating Gl and the absorption grating G2.

[0096] In step 320 , the X-ray beam 52 is emitted onto the object 50 .

[0097] In step 330, information about the X-ray phase shift caused by the object 50 is detected as moiré fringes by the detector 220. In other words, the imaging device captures an image of the object 50 by imaging the moiré fringes that retain the phase information of the object 50. Performing a phase recovery process (such as a Fourier transform) based on the detection result enables a phase image of the object to be obtained. Additional processing for phase detection is performed according to known phase contrast detection techniques.

[0098] It should be noted that embodiments of the present invention are described with reference to different subject matters. Specifically, some embodiments are described with reference to method-type claims, while other embodiments are described with reference to apparatus-type claims. However, those skilled in the art will appreciate from the foregoing and the above description that, unless otherwise noted, any combination of features relating to different subject matters, in addition to any combination of features belonging to one type of subject matter, is also considered disclosed by this application. However, all features may be combined to provide synergistic effects that exceed the simple sum of the features.

[0099] Although the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplary rather than restrictive. The present invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention from a study of the drawings, the description, and the appended claims.

[0100] In the claims, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. A single processor or other unit may perform the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A method (100) for generating an X-ray grating of an imaging device, the imaging device being used for X-ray dark field imaging and / or X-ray phase contrast imaging, the method comprising the following steps: a) producing (110) a resist negative grating (10) having a plurality of periodically arranged grating webs (12) and grating openings (14) on a flat sample (16); b) filling (120) the grating openings on the flat sample by electroplating by continuing the electroplating up to the height of the grating web to form a grating sheet (18); c) processing (130) a window (26) on top of the resist negative grating (22), said window enabling the introduction of a top bridge (24) substantially perpendicular to the grating web; d) bending (140) the resist negative grating to a desired radius; and e) Filling (150) the window by electroplating to form the top bridge after bending the resist negative grating.

2. The method according to claim 1, further comprising: The resist negative grating between the grating flakes is removed after the electroplating is performed.

3. The method according to claim 1 or 2, in, In step d), a frame is provided which allows the resist negative grating to be precisely bent to the desired radius.

4. The method according to claim 3, in, The bending radius of the frame is compatible with a mounting location in the imaging device close to an X-ray tube.

5. The method according to claim 3, in, The frame is made of a non-conductive material, or the frame is completely covered by a non-conductive material.

6. The method according to claim 1 or 2, in, Step e) further comprises selecting a temperature for the electroplating, wherein the selected temperature is selected such that geometrical changes and / or mechanical stresses of the X-ray grating are minimal or near-minimal under operating conditions of the X-ray grating in the imaging device.

7. The method according to claim 1 or 2, in, The top bridge is shaped such that under operating conditions of the X-ray grid in the imaging device, mechanical stresses due to the top bridge are minimal or near minimal.

8. The method according to claim 1 or 2, in, The top bridge and the grating sheet are made of the same material.

9. The method according to claim 1 or 2, in, The grating sheet is electroplated with a highly X-ray absorbing material; and Wherein, the top bridge is electroplated with a low X-ray absorption material.

10. The method according to claim 1 or 2, in, The resist negative grating includes a plurality of stabilizing structures for stabilizing the mesh.

11. The method according to claim 10, in, The stabilizing structure comprises a bridge structure and / or a sun ray structure.

12. The method according to claim 1 or 2, in, The curvature in step d) is a positive curvature or a negative curvature.

13. An imaging device (200) for capturing an image of an object, comprising: X-ray source (210); Source grating (G0); a diffraction grating (G1) for diffracting X-rays emitted from the X-ray source; an absorption grating (G2) for absorbing a portion of the X-rays diffracted by the diffraction grating; as well as a detector (220) for detecting the X-rays having passed through the absorption grating; wherein at least one of the source grating, the diffraction grating, and the absorption grating is manufactured by a process comprising the following steps: a) producing a resist negative grating (10) having a plurality of periodically arranged grating webs (12) and grating openings (14) on a flat sample (16); b) filling the grating openings on the flat sample by electroplating by the following operation: continuing the electroplating up to the height of the grating web to form a grating sheet (18); c) processing a window (26) on top of the resist negative grating (22), said window enabling the introduction of a top bridge (24) substantially perpendicular to the grating web; d) bending the resist negative grating to a desired radius; and e) Filling the window by electroplating to form the top bridge after bending the resist negative grating.

14. A method (300) for performing X-ray phase contrast and / or dark field imaging, comprising: positioning (310) an object (50) between the source grating (G0) and the diffraction grating (G1) or between the diffraction grating (G1) and the absorption grating (G2) of the imaging device according to claim 13; emitting (320) an X-ray beam (52) onto the object; and The X-ray beam having passed through the object, the source grating, the diffraction grating and the absorption grating of the imaging device is detected (330) for acquiring image data.

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