Shielding mask for scattered ionizing radiation and production method thereof

Abstract

To provide an improved mesh for shielding scattered X-rays for an X-ray imaging device.SOLUTION: In a shielding mesh (1) for scattered X-rays, the shielding mesh (1) comprises a plate-like body (3) having a first surface (5) and a second surface (7) opposite the first surface (5). The plate-like body (3) has an arrangement of wells (15) open toward the second surface (7) of the plate-like body (3), the plate-like body (3) having a mesh composed of trenches (11) open toward the first surface (5), the trenches (11) being filled with an X-ray absorbing material (13), the trenches (11) extending between the wells (15) at a distance from the wells (15) viewed from one of the surfaces (5, 7) so as to leave walls (19) between the wells and the trenches (11).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates, in general, to imaging methods using ionizing radiation, particularly X-ray imaging. In particular, the present invention relates to a mask for shielding a radiation detector from scattered ionizing radiation.

[0002] Computed tomography (CT) is a well-known imaging technique that uses ionizing radiation, often employed as a radiological process in diagnostics. In this method, an X-ray fan beam is transmitted through the object being examined from various planes and directions. A computer is then used to reconstruct a three-dimensional model of the object from the spatially resolved recorded signals.

[0003] Digital volume tomography (DVT) is a form of computed tomography. In this method, radiation from a point-like X-ray source is transmitted through the object and recorded by a matrix detector.

[0004] Blocking scattered radiation before it reaches the detector is advantageous for improving the signal-to-noise ratio, that is, the resolution and contrast of the tomographic image. For this purpose, it is known to use a grating to absorb radiation that enters the detector at an oblique angle to the direct, linear path to the X-ray source. In one currently used embodiment of such a grating, a stack of lead strips is provided, with paper strips acting as spacers between the lead strips. The disadvantage in this case is that such a structure suppresses scattered radiation only on a single plane, i.e., only perpendicular to the surface of the lead strips. Furthermore, such a structure is not very mechanically stable and can easily undergo permanent deformation. In addition, such a structure generally cannot be very finely structured, which in turn can affect the spatial resolution of the tomography system.

[0005] International Publication No. 2007 / 034352 describes an X-ray absorbing grating in which thin layers of X-ray absorbing materials such as tungsten and molybdenum are embedded in a rigid foam material and mechanically stabilized within this rigid foam material.

[0006] U.S. Patent Application Publication No. 2016163408 describes the manufacture of an X-ray absorption grating using a silicon substrate. In this method, voids are formed in the silicon substrate by etching, and these voids are galvanically filled with an X-ray absorbing metal.

[0007] An X-ray absorption grating, as described in U.S. Patent No. 5,581,592, is advantageously manufactured by introducing channels into a plastic substrate by sawing. This can be done using a saw blade, such as the one used to cut silicon wafers in chip manufacturing. The X-ray absorption alloy is then introduced into the channels by melting it. For this to work, the substrate must be able to withstand the melting temperature without softening.

[0008] The present invention is based on the problem of providing an improved grating for shielding scattered ionizing radiation, particularly X-rays. This problem is solved by the subject matter of the independent claims. Advantageous embodiments of the present invention are shown in the respective dependent claims.

[0009] Therefore, the present invention relates to a shielding grating for scattered X-rays, and more particularly to a shielding grating for an X-ray imaging apparatus, such as an X-ray computed tomography apparatus, wherein the shielding grating is - A plate-like body having a first surface and a second surface opposite to the first surface. The plate-like body is equipped with, - It has an arrangement of wells that open toward the second surface of the plate-like body, - The plate-like body has a grid composed of trenches opening toward the first surface, - The trench is filled with X-ray absorbing material. - The trench provides a shielding grate that extends between the wells at a distance from the wells when viewed from one side, such that a wall remains between the wells and the trench.

[0010] Therefore, when viewed from the direction of one side of the plate-like body, wells are positioned between the trenches. At the location of the wells, X-rays can easily pass directly through the plate-like body. Since walls made of the plate-like material are positioned around the wells, sufficient mechanical stability is provided to the plate-like body, even if the X-ray absorbing material in the trenches itself cannot withstand mechanical loads. The wells and trenches open toward different sides of the plate-like body, and therefore the wells are closed toward the side from which the trenches open, so it is easy to avoid filling the wells at the same time as filling the trenches with the X-ray absorbing material. In the intent of this disclosure, the X-ray absorbing material means a material whose X-ray absorption coefficient for X-rays with an energy of 69.5 keV is at least three times that of the plate-like material. According to an alternative or additional preferred embodiment, the X-ray absorbing material is a material having a density at least four times that of the plate-like material. It is also important for the effect of the X-ray absorbing material to include elements with particularly large atomic numbers. In a further alternative or additional embodiment, the X-ray absorbing material is a material having at least 10% by weight of an element having an atomic number of at least Z=56, and advantageously at least 25% by weight, particularly preferably at least 50% by weight, of such elements having an atomic number of Z≧56. In the spirit of this disclosure, X-ray absorbing materials also include materials that absorb ionizing radiation in general, and in this case, electromagnetic radiation. Such materials also typically have high absorption efficiency for particulate ionizing radiation. Thus, this disclosure as a whole relates to the aforementioned shielding gratings for scattered ionizing radiation. In this spirit, the term X-ray absorbing material is a simplification for all materials suitable for absorbing high-energy radiation. Furthermore, X-ray absorbing materials also include X-ray opaque materials.

[0011] The present invention will be described in more detail below with reference to the figures. Here, the same reference numerals in the figures refer to the same or corresponding elements. [Brief explanation of the drawing]

[0012] [Figure 1]It is a diagram schematically showing a computed tomography apparatus having a shielding grid. [Figure 2] It is a cross-sectional view of the shielding grid. [Figure 3] It is a top view of the shielding grid. [Figure 4] It is a diagram showing a modified example of the shielding grid. [Figure 5] It is a cross-sectional view of a modified example of the shielding grid having wells oriented toward a point source. [Figure 6] It is a diagram showing a laser processing apparatus for introducing a filamentous damage into a plate-like body. [Figure 7] It is a cross-sectional view of the plate-like body into which the filamentous damage has been introduced. [Figure 8] It is a diagram showing the plate-like body after etching. [Figure 9] It is a diagram showing the plate-like body after filling the trench with an X-ray absorbing material. [Figure 10] It is a diagram showing a modified example having a thinned plate-like body according to the embodiment of FIG. 9. [Figure 11] It is a diagram schematically showing a cross-section of the X-ray absorbing material. [Figure 12] It is a diagram showing the particle size distribution of the pulverized solder glass. [Figure 13] It is a diagram showing the particle size distributions of the pulverized glass, two kinds of metal dusts, and their mixture. [Figure 14] It is a diagram showing a further development form of the embodiment shown in FIG. 2. [Figure 15] It is a diagram showing a further development form of the embodiment shown in FIG. 2. [Figure 16] It is a diagram showing the process steps for filling the trench of the shielding grid with an X-ray absorbing material. [Figure 17] It is a diagram showing the process steps for filling the trench of the shielding grid with an X-ray absorbing material. [Figure 18] It is a diagram showing the process steps for filling the trench of the shielding grid with an X-ray absorbing material. [Figure 19]This figure shows the process steps for filling the trenches of the shielding grating with X-ray absorbing material. [Figure 20] This figure shows the process steps for filling according to a further embodiment of the manufacturing method. [Figure 21] This figure shows the process steps for filling according to a further embodiment of the manufacturing method. [Figure 22] This figure shows the process steps for filling according to a further embodiment of the manufacturing method. [Figure 23] This figure shows the process steps for filling according to a further embodiment of the manufacturing method. [Figure 24] This diagram shows the process steps for filling gaps in trench filling. [Figure 25] This diagram shows the process steps for filling gaps in trench filling. [Figure 26] This figure shows one modified example of a method for trench filling with metal powders of different particle sizes and morphologies. [Figure 27] This figure shows one modified example of a method for trench filling with metal powders of different particle sizes and shapes. [Figure 28] This figure shows one embodiment of trench filling, in which a dispersion is flowed into the trench. [Figure 29] This figure shows one embodiment of trench filling, in which a dispersion is flowed into the trench. [Figure 30] This figure shows one embodiment of trench filling, in which a dispersion is flowed into the trench. [Figure 31] This figure shows a setup for laser processing for trench manufacturing.

[0013] Detailed description of the drawing The present invention relates not only to a shielding grate but also to an X-ray imaging apparatus, such as a computed tomography apparatus. An X-ray imaging apparatus generally comprises an X-ray source, an X-ray detector, and a shielding grate 1 positioned in front of the X-ray detector for detecting X-rays emitted from the X-ray source. The function of the shielding grate 1 provided by the present invention will be described with reference to Figure 1. Figure 1 shows a schematic structure of an X-ray imaging apparatus 2. In the illustrated embodiment, the X-ray imaging apparatus 2 comprises an X-ray source, in particular an X-ray tube 30, the X-ray tube 30 comprising a vacuum valve 33, an anode 31 and a cathode 32 located in the vacuum valve 33. During operation, X-rays are emitted from the anode. The object to be examined, such as a patient or a part of the body, is placed between the X-ray tube 30 and the X-ray detector 39.

[0014] The present invention is particularly suitable for so-called cone-beam computed tomography. In this method, instead of performing a sequential scan with a rotating fan beam, a cone beam emitted from the X-ray tube 30 is detected by a matrix detector. Data suitable for a tomographic image can be obtained from the X-rays 35 that pass linearly through the object to be examined. On the other hand, scattered X-rays do not contain positional information and only increase noise. As can be seen from Figure 1, scattered X-rays are incident on the X-ray detector 39 at an angle to the linear path between the X-ray tube and the detector. It is desirable that the shielding grating 1 allows only the X-rays 35 coming linearly from the X-ray tube 30 to pass through with as little attenuation as possible, while absorbing the scattered X-rays 36. This is achieved by a passage defined by the gaps in the grating, which is made of an X-ray absorbing material, and this passage allows only light rays at a small angle to the linear path to pass through.

[0015] Figure 2 shows a cross-section of the shielding grid 1. The shielding grid 1 comprises a plate-like body 3 as a support or base element. According to one particularly preferred embodiment of the present invention, and not limited to the illustrated example, the plate-like body 3 is plate glass. In particular, glass is particularly preferred as a material because it does not exhibit ductility and therefore does not undergo permanent deformation due to mechanical action. This avoids changes in collimation properties or selectivity between direct and scattered X-rays. Another reason is that, since glass can now be structured very finely, it has become easier to manufacture shielding grids with similarly high selectivity. There is also the advantage that the thermal expansion of the glass can be controlled by appropriately selecting the type of glass. Therefore, for example, the displacement due to the temperature of the grid relative to the pixels of the X-ray detector 39 can be minimized. This also applies to relatively large dimensions. Therefore, according to one development, and not limited to the specific material of the shielding grid, the shielding grid 1 is at least 0.25 m 2 It is provided that it has an area of ​​the above. In particular, the area is further provided to be at least 1 / 3 m 2 This may also be the case. For example, according to one embodiment, a shielding grid having dimensions of 600 mm x 600 mm is provided.

[0016] The plate-like body 3 has two opposing surfaces 5 and 7. Advantageously, since the plate-like body 3 is formed parallel to its surface, the opposing surfaces 5 and 7 also extend parallel to each other. As can be seen in Figure 2, wells are introduced on both surfaces 5 and 7. The well introduced on the first surface 5 is in this case formed as a trench 11. On the opposing second surface 7, a well 15 is introduced, located between the trenches 11. The well 15 opens toward the second surface 7. Correspondingly, the trench 11 opens toward the opposing first surface 5. Because the trench 11 opens toward the first surface 5, the trench 11 can be filled with X-ray absorbing material 13. Since the trench 11 extends substantially perpendicularly within the plate-like body 3, the X-ray absorbing material present within it can effectively absorb X-rays incident on the plate-like body 3 at an oblique angle. For illustrative purposes, substantially perpendicularly incident X-rays 35 that can pass through the plate-like body 3 through the well 15 are drawn in. On the other hand, obliquely incident X-rays 36, such as those caused by scattering at the object being inspected, are absorbed by the X-ray absorbing material 13. Therefore, the well 15 plays a role in minimizing the interaction between the X-rays and the material of the plate-like body 3, preferably glass, even if the plate-like body 3 is thick. The X-rays simply need to pass through the bottom wall 16, which is much thinner than the thickness of the plate-like body 3.

[0017] In general, the plate-like body 3 is preferably at least 2 millimeters thick, and preferably at least 3 millimeters thick. This allows for the introduction of correspondingly deep trenches 11, and consequently, good shielding of obliquely incident scattered radiation. However, it is also advantageous for the thickness to be less than 10 millimeters in order to still allow the trenches 11 to be easily filled with X-ray absorbing material.

[0018] A wall 19 exists between the well 15 and the trench 11. In the region of these walls, the thickness of the plate-like body 3 does not decrease, but the wall 19 can be kept narrow. Furthermore, these walls provide the mechanical stability of the arrangement.

[0019] To further enhance mechanical stability, according to one advanced embodiment of the present invention, an edge region 27 of the plate-like body 3 can be provided, which does not have wells 15 or trenches 11. Thus, this edge region functions as a stabilizing frame. Although not limited to the illustrated example, the edge region can have a width of at least twice the period length of the sequence of trenches and wells. The period of the trenches 11, or the spacing of the trenches 11 measured from center to center, is up to 500 μm according to one preferred embodiment. This is particularly advantageous for achieving high spatial resolution in imaging.

[0020] The arrangement of the trenches 11 and wells 15 may, in particular, be matched to the pixel pitch of the detector. Especially when such pixel matching is performed, even small changes in the shielding grating 1 due to mechanical deformation, for example, can result in considerable transmission loss. For this reason, glass is a particularly preferred material for the plate-like body 3. In general, borosilicate glass is particularly suitable in terms of both stability and structuring ability. However, other materials such as glass ceramics, ceramics, or certain plastics are also possible. In addition to borosilicate glass, soda-lime glass and aluminosilicate glass are also generally suitable materials for the plate-like body. One criterion that can be used when selecting the material for the plate-like body 3 is generally its linear thermal expansion coefficient. By bringing this closer to the expansion coefficient of the X-ray absorbing material, temperature-induced mechanical stress can be kept low. For example, if the X-ray absorbing material 13 has a high thermal expansion coefficient, soda-lime glass may be suitable.

[0021] Figure 3 shows a top view of the first surface 5 of the shielding grid 1. According to a preferred evolution of the present invention, the grid 9 of the trench 11 is formed as an intersecting grid, as shown in the illustrated example. The intersecting trenches 11 form cells, and the wells 15 are arranged within these cells. However, other arrangements are also possible. For example, high transmittance to direct X-rays can be achieved using a hexagonal grid. Such a modification having a hexagonal grid is shown in Figure 4.

[0022] In general, the shape of the grid 9 can be adapted to the shape of the pixels in the detector 39. Therefore, in addition to the examples shown using Figures 3 and 4, other shapes are also possible. For example, the grid 9 can define rectangular, circular, triangular, or even octagonal channels.

[0023] The illustrations in Figures 3 and 4 should be understood as merely schematic. In the illustrations, the trench 11 is clearly shown to be narrower than the well 15. However, in practice, in order to achieve good shielding of scattered radiation, it is usually advantageous to make the widths of the trench 11 and the well 15 similar, or consequently reduce the distance from trench to trench in relation to the width of the trench 11. In this respect, the illustration in Figure 2 is close to a preferred embodiment. In this respect, according to one evolution of the present invention, the width of the trench 11 is provided to differ from the width of the well 15 by up to twice.

[0024] Furthermore, a large ratio of depth to trench width is particularly advantageous for the transmission of direct X-rays and the shielding of scattered radiation. In particular, if the depth-to-width ratio is 40:1 or greater, it is possible to fill the trench 11 with X-ray absorbing material using the method described later. However, if the aspect ratio is too high, sufficiently uniform or complete filling may not be guaranteed. Therefore, it is preferable to limit the width-to-depth ratio to 150:1 or less. Here again, it is clear that the drawings are merely schematic. The aspect ratio of the trench 11 in Figure 2 is considerably smaller than 40:1. According to an alternative or advantageously additional development, the width of the trench 11 is a maximum of 100 μm, and advantageously a maximum of 50 μm. This is generally advantageous for uniform projection of the detector by avoiding shadowing by reducing the width. A large depth, or a combination of the corresponding aspect ratio, allows for a high X-ray absorption rate even with a small trench width 11.

[0025] A further alternative or additional factor for good shielding of scattered radiation and transmission of direct radiation is the depth of the trench 11. Advantageously, the depth of the trench 11 is at least 1.5 millimeters, and advantageously at least 2 millimeters.

[0026] Similarly, the longer the passages or channels defined by the trenches 11 of the grid 9 are, the more advantageous it is for the property of high shielding of scattered radiation. The longer these channels are relative to their width, the greater the selectivity of the grid for the passage of direct radiation and the shielding of obliquely incident scattered radiation. Thus, according to another development of the present invention, the distance between the centers of two adjacent trenches is provided to be less than their depth. Advantageously, the distance between centers is even less than one-third of the depth of the trenches 11.

[0027] Finally, for good shielding, it is desirable that the walls of the trench 11 extend as perpendicularly as possible to the planes of surfaces 5 and 7. In this regard, it is preferable that the deviation of the angle between the walls 25 of the trench 11 and the first surface 5 from a right angle is less than 5°. Small taper angles of less than 5° can also be achieved, particularly in plate glass, by the manufacturing methods described later. This applies to special cases of trenches 11 and wells 15 cut perpendicularly into a plate-like body.

[0028] In the example shown in Figure 2, the trenches 11 extend parallel to each other in a direction perpendicular to the planes 5 and 7. Such an arrangement is particularly suitable when the detected X-rays are incident as parallel beams, i.e., when the X-ray source is far away. However, typically, X-ray imaging devices such as computed tomography scanners use closer X-ray sources, so that a conical beam of light strikes the shielding grating. Therefore, in general, in one embodiment of the present invention, the trenches 11 exhibit a change in inclination, so that the walls of the trenches 11 extend along a direction pointing to a common virtual point source. In other words, the trenches 11 are introduced into the plate-like body 3 with an inclination such that the central axis of the channel defined by adjacent trenches 11 points to a common virtual point source. Accordingly, this also applies to the central axis of the well 15. Therefore, in one embodiment of the present invention, the central axis 17 of the well 15 is directed toward a common virtual point source. Such an arrangement is schematically shown in Figure 5. The central axis 17 of the well 15 generally coincides with the central axis of the channel 12 defined by the adjacent trench 11. The channel 12 also contains the material of the plate-like body 3 in addition to the well 15, and this material forms the walls 16 and 19. As is clear from the figure, the trench 11 is also directed toward the virtual point source 18, so the walls of the trench 11 extend in the direction of the point source 18. Due to the conical ray path, the widths of the well 15 and the trench 11 also change along the path within the plate-like body 3, as shown in the figure. Here, the width of the side facing the point source 18 (here, the second surface 7) is smaller than the width of the opposing surface. However, in practice, this is usually not necessary, because the point source is generally much farther away from the thickness of the plate-like body 3 than shown in Figure 5. Therefore, it is preferable that the trench 11 and the well 15 have a constant width in the direction of the rays, or in the direction perpendicular to surfaces 5 and 7. Thus, this change in width corresponds to the illustration in Figure 2.

[0029] The method for manufacturing the shielding grating 1 according to the present invention will be described below. The method for manufacturing the shielding grating 1 against scattered X-rays is as follows: - A step of providing a plate-like body 3 having a first surface 5 and a second surface 7 facing the first surface 5, - A step in which a laser beam is irradiated onto a plate-shaped body 3, wherein the material of the plate-shaped body 3 is transparent to the laser beam, so the laser beam penetrates the plate-shaped body 3, and at that time, - A step in which a laser beam is introduced such that it leaves filamentous damage along the path of the laser beam passing through the plate-like body 3, and the first group of filamentous damage ends on the first surface and the second group of filamentous damage ends on the second surface 7, - A step of removing the material of the plate-like body 3 in the regions of the first and second groups of filamentous damage by etching the plate-like body 3 with an etching medium, - By removing the material from the region of the second group, an array of wells 15 opening toward the second surface 7 of the plate-like body 3 is formed. - The step of removing the material from the region of the first group so that a grid 9 consisting of trenches 11 opening toward the first surface 5 is formed, and then - A step of filling the trench 11 with X-ray absorbing material 13 and Includes.

[0030] Ultrashort pulse lasers are particularly suitable for introducing filamentous damage. Figure 6 shows a laser processing apparatus for introducing filamentous damage 41 into a plate-like body 3, and then forming trenches 11 and wells 15 from this damage in an etching process. The apparatus 50 comprises an ultrashort pulse laser 51 with an upstream focusing optical system 52 and a positioning unit 53. The positioning unit 53 allows the incident point 54 of the laser beam 40 of the ultrashort pulse laser 51 to be positioned laterally on one of the surfaces 5, 7 of the plate-like body 3 to be processed. In the illustrated example, the positioning unit 53 includes an xy table on which one of the surfaces 5, 7 of the plate-like body 3 is placed. However, alternatively or additionally, the incident point 54 of the laser beam 40 can be moved on the plate-like body 3 by making the optical system movable and moving the laser beam 40. The focusing optical system 52 focuses the laser beam 40 to a focal point that is elongated in the direction of the beam, i.e., transversely to the irradiation surface of the plate-like body 3. Such a focal point can be formed, for example, by a conical lens (so-called axicon) or a lens with large spherical aberration. The positioning unit 53 and the ultrashort pulse laser 51 are advantageously controlled by a programmable calculation unit 55. In the illustration in Figure 6, the laser beam 40 is incident perpendicularly on the plate-like body 3. However, according to one preferred embodiment, the positioning unit 53 and / or the focusing optical system 52 may be configured to allow oblique irradiation in order to form filamentous damage 41 that is in the longitudinal direction parallel to the central axis 17, respectively, or generally parallel to the direction to the virtual point source 18. Thus, in general, although not limited to the specific embodiments illustrated herein, in advanced forms of this method, it is provided that the filamentous damage 41 is introduced at least partially obliquely to one of the surfaces 5,7 of the plate-like body 3. By using the positioning unit 53 to continuously introduce the positions of incident points or filamentous damage 41 distributed on the plate-like body 3 according to a predetermined pattern, a predetermined pattern can be formed, and these patterns are then finished in a subsequent etching step.

[0031] According to one embodiment, the following parameters can be used for the laser beam: The wavelength of the laser beam is 1064 nm, which is typical for a YAG laser. A laser beam with a raw beam diameter of 12 mm is formed and then focused by a biconvex lens optical system with a focal length of 16 mm. The pulse duration of the ultrashort pulse laser is less than 20 ps, ​​and in one embodiment, it is about 10 ps. The pulses are emitted in bursts having 2 or more pulses, preferably 4 or more pulses. The burst frequency is 12 to 48 ns, about 20 ns in one example, the pulse energy is at least 200 microjoules, and the burst energy is correspondingly at least 400 microjoules. According to one embodiment, the ultrashort pulse laser can be operated at a burst or pulse packet repetition frequency of 1 kHz to 1000 kHz, advantageously 2 kHz to 100 kHz, and particularly preferably 3 kHz to 200 kHz. Here, this repetition frequency and / or scanning speed can be selected so that a desired distance between adjacent damage / channels is achieved. As a beam source, other variations of the Nd:YAG laser, such as a Yb:YAG laser operating at emission wavelengths of 532 nm, 355 nm, or even 1030 nm, produced by frequency doubling (SHG) or frequency tripling (THG), can be appropriately used.

[0032] By conditioning the laser beam, this method can be specifically adapted for the fabrication of blind holes / channels. In particular, very short focal lengths, especially f<20mm, can be used. According to an alternative or additional embodiment, an intensely expanded raw beam is used. Particularly preferably for this purpose, the laser beam has a beam diameter of at least 4mm when it strikes the lens or focusing optical system.

[0033] Another approach is to alter the intensity distribution. To achieve this, the maximum intensity may be shifted from the optical axis to the edge region of the focusing optical system, or it may be distributed over a larger area overall. Beam profiles with these characteristics include flat-top profiles and donut profiles.

[0034] Since the orientation of wells and trenches to a point source also involves oblique illumination, it is even more advantageous to perform coupling with polarization orientation parallel to the substrate surface, especially near the Brewster angle. Furthermore, asymmetric illumination of the focusing optical system can be performed as needed to obtain a larger incident angle.

[0035] Embodiments relating to methods for introducing filamentous damage and suitable laser parameters therefor, as well as parameters for subsequent etching, can also be referenced from DE102017101673.2, DE102018110211.9 and PCT / EP2021 / 077030. These applications also constitute the subject matter of this disclosure with respect to embodiments for introducing filamentous damage 41 and parameters for laser irradiation and etching.

[0036] Figure 7 shows a plate-like body 3 with filamentous damage introduced. The filamentous damage 41 can be divided into two groups 43 and 44. Here, the filamentous damage 41 of the first group 43 ends on the first surface 5, and the filamentous damage 41 of the second group 44 ends on the second surface 7. Although not limited to the illustrated example, it is generally particularly preferable that at least some, preferably all, or both groups 43 and 44 of the filamentous damage 41 end within the plate-like body 3 as shown. This makes it easy to form wells 15 in the form of blind holes, or trenches 11 ending within the plate-like body, even when the entire plate-like body is exposed to the etching medium during subsequent etching. Since the filaments preferably pass through 50% to 90% of the glass thickness, after the etching process, the channels or blind holes / voids formed by the wells 15 and trenches 11 preferably reach 55% to 95% of the glass thickness.

[0037] Therefore, the filamentous damage 41 ends on one side inside the plate-like body and on the other side on one of the surfaces 5 and 7. As can be seen from Figure 6, the filamentous damage 41 is also introduced obliquely depending on the angle of direction to the hypothetical point source assumed later. Here, according to one embodiment of the present method, it is not necessary to turn the plate-like body 3 over to introduce the filamentous damage 41. It is sufficient to adapt or change the position of the long focal point of the laser beam 40. For this purpose, the position of the lens and / or the position of the plate-like body 3 can be changed. For example, when the laser beam 40 is irradiated onto the first surface 5 in the plate-like body 3 according to Figure 7, the beginning of the long focal point for the filaments of group 43 can be located on or in front of the plate-like body 3. Next, in order to introduce the filaments of group 44, the focal point can be shifted in the direction of the laser beam 40 so that the beginning of the long focal point is located inside the plate-like body 3. Therefore, although not limited to a specific embodiment, one embodiment of the present method provides that a laser beam 40 is irradiated onto the same surfaces 5, 7 of the plate-like body 3, and the position of the focal point of the laser beam 40 relative to the plate-like body is changed to form at least a portion of the filamentous damage 41 of both groups 43, 44 in a direction along the laser beam 40.

[0038] When glass is used as the material for the plate-like body 3 and a caustic solution is used as the etching medium, characteristic surface topography can be achieved on the walls of the trenches 11 and wells 15, especially when etching is performed slowly. In particular, the surfaces of the trenches 11 and wells can have a plurality of small, adjacent dome-shaped wells. Advantageously, the dome-shaped wells have a depth of less than 10 μm, preferably less than 5 μm, and preferably less than 2 μm, where the depth is determined by the difference between the center of the well bottom and the central peak of the ridge surrounding the well. The dome-shaped wells are described in detail in DE102017101673.2, DE102018110211.9 and PCT / EP2021 / 077030, and the contents relating thereto are also fully covered by this disclosure. Surface topography with dome-shaped wells provides good connectivity between the plate-like body 3 and the X-ray absorbing material. In particular, strong connectivity can be achieved when the X-ray absorbing material includes molten glass, such as solder glass. Here, the wells increase the surface area for material bonding, achieving proper interlocking of the two materials.

[0039] Figure 8 shows the plate-like body 3 after etching. The material of the plate-like body 3 can be etched much more rapidly along the filamentous damage 41 than in areas without such damage. Therefore, during etching, the material, preferably glass, is removed while expanding the filamentous damage 41. The channels thus formed eventually integrate to form a desired structure in the form of a trench 11 extending into the plate-like body 3, starting from the first surface 5, and a well 15 extending into the plate-like body 3, starting from the second surface 7. Depending on the inclination of the filamentous damage 41, the trench 11 and well 15 are also oriented toward a virtual point source, as shown in Figure 5.

[0040] Finally, on surface 5, the X-ray absorbing material 13 can be filled into the trench 11, for example, in the form of a paste, thereby obtaining the shielding grid 1 shown in Figure 9. According to one advanced version of the method, although not limited to the specific embodiments shown, it is also possible to thin the plate-like body 3 after filling with the X-ray absorbing material 13, for example, to reduce X-ray absorption. In Figure 9, a dashed line is drawn parallel to and adjacent to the second surface 7. Here, if the plate-like body 3 is ground on surface 7 up to this line, a plate-like body 3 as shown in Figure 10 is obtained. According to a further alternative or additional advanced version, also realized in the embodiment of Figure 10, when the plate-like body is thinned, the trench 11 and, consequently the X-ray absorbing material 13 are exposed on the second surface 7. Thus, an embodiment is obtained in which the trench 11 is generally open at least partially on both sides 5, 7 of the plate-like body 3. This embodiment is not limited to thinning; for example, the filamentous damage 41 can be introduced at least partially throughout the entire plate-like body 3, such that the filamentous damage 41 ends on both sides 5, 7. It is also possible to introduce adjacent filamentous damage 41 that alternately end on one or the other side 5, 7. Subsequently, during etching, the channels formed along the filamentous damage 41 connect to each other, forming a trench 11 that continuously connects both sides 5, 7. However, in this case, direct connections between sections of the plate-like body 3 adjacent to the trench 11 may no longer exist. However, to maintain mechanical stability, bridge-like structures obtained by the reduced depth of the trench 11 can be left as they are. As an alternative or additional method, an X-ray absorbing material can be provided to material-bond with the walls of the trench 11. In general, not limited to the modifications of Figure 10, it is preferable to provide glass, particularly solder glass, as a component of the X-ray absorbing material 13, in which case the glass is melted and thus material-bonded with the material of the plate-like body 3, advantageously producing a similarly integral glass. In some cases, melting the glass is sufficient. Suitable components of the X-ray absorbing material 13 are, in particular, lead and / or bismuth-containing glass, such as lead glass, whether in molten form or not.Lead and / or bismuth-containing glass has a good shielding effect against ionizing radiation, particularly X-rays, depending on its lead or bismuth content. Furthermore, the glass can be fully or partially crystallized. Special crystallized glasses and soldered glasses are known. However, in this case as well, in the spirit of this disclosure, molten or initially molten glass is mentioned as a component of the X-ray absorbing material. Therefore, in general, one embodiment is provided in which the X-ray absorbing material 13 comprises initially molten or molten glass.

[0041] Furthermore, if the X-ray absorbing material 13 contains molten solder glass, it is advantageous for material bonding between the X-ray absorbing material 13 and the plate-like body 3 and / or for the permanent and stable fixation of the X-ray absorbing material 13 in the trench 11. Here, the presence of lead-containing solder glass is highly advantageous. Lead oxide, in particular, as a glass component, is suitable for providing a low softening point while simultaneously providing a high shielding effect. In general, it is preferable that the glass of the X-ray absorbing material 13 and the glass of the plate-like body 3 possess at least one of the following characteristics, so that the glass can be melted in the trench 11 without deforming the plate-like body 3: - The glass of the X-ray absorbing material 13 is the glass transition temperature T of the glass of the plate-like body 3. g A glass transition temperature T that is at least 100°C lower, preferably at least 160°C, or even at least 220°C lower. g Having, - The glass of the X-ray absorbing material 13 is 10 4 It has a viscosity of dPa·s and a processing temperature that is at least 100°C, particularly at least 200°C, and especially preferably at least 250°C lower than the processing temperature of the glass of the plate-like body 3. - The glass of the X-ray absorbing material 13 is 10 4 It has a viscosity of dPa·s and a processing temperature lower than the softening point temperature of the glass plate 3, at which point the softening point is 10 7.6 It is defined by viscosity in dPa·s.

[0042] In one example, for the X-ray absorption material 13, a solder glass of type G017-52 manufactured by Schott-AG is used. In the case of the plate-like body 3 composed of Borofloat 33 glass manufactured by Schott-AG, the difference in the glass transition temperature T g is 263 °C. The viscosity of the solder glass G017-052 is 10 7.6 dPa·s at 347 °C. This temperature is 218 °C lower than the softening point of Borofloat 33 glass.

[0043] The glass as a component of the X-ray absorption material has yet another advantage in relation to the arrangement described herein, regardless of whether the glass contains lead. As a material prone to brittle fracture, the glass can be very finely pulverized. At that time, the glass dust is very suitable for filling the narrow and deep trenches 11, for example, as a component of a paste-like formulation. At that time, the filling can be easily performed, for example, by a doctor blade. In one exemplary embodiment, after filling the trench 11 with the paste-like formulation, it is preferably dried at 100 °C to 200 °C. Especially when the aspect ratio of the trench 11 is large, the filling and drying can be repeated to achieve complete filling of the trench 11. Once sufficient filling of the trench 11 has been performed, a heat treatment at 350 °C to 450 °C can be carried out, and by melting the glass of the formulation at that time, an X-ray absorption material 13 firmly connected to the wall of the trench 11 can be obtained. Therefore, according to one embodiment, there is provided a method of filling the trench 11 with powdered glass, preferably the solder glass 21 as a component of the X-ray absorption material 13, preferably a mixture of powdered glass and particles, and forming a strong X-ray absorption material 13 adhering to the wall of the trench 11 by melting or initially melting the solder glass 21.

[0044] Figure 11 schematically shows a preferred embodiment of the X-ray absorbing material. According to this embodiment, the X-ray absorbing material 13 generally comprises particles, preferably metal particles 23. In a particularly preferred evolution, the X-ray absorbing material 13 comprises particles embedded in a molten material, particularly metal particles 23 and / or mineral particles and / or ceramic particles. In the spirit of this disclosure, the component in granular form or as particles is understood to include, in addition to metal granules or particles, ceramics or glass-ceramics or semi-crystalline glass, and further, crystals (single-crystal or polycrystalline crystals) as granules or particles, or combinations thereof. The molten material may preferably be molten glass or solder glass 21, as in the illustrated example. The glass provides a strong bond between the X-ray absorbing material 13 and the plate-like body 3 that can withstand mechanical loads in general. Therefore, although not limited to a particular embodiment, one development of the manufacturing method is provided, which involves providing a paste containing glass particles and particles, preferably metal particles 23, filling a trench 11 with the paste, preferably by a doctor blade, and heating a plate-like body 3 containing the glass particles and particles in the trench 11 to soften the glass particles and obtain an X-ray absorbing material 13 in which particles, preferably metal particles 23, are embedded in the glass.

[0045] While not limited to specific embodiments, one preferred embodiment provides that the paste comprises an organic solvent or organic suspension agent in addition to various solid components, preferably at least glass dust and metal dust, or metal particles 23. Thus, in general, the paste is, in a preferred embodiment, a mixture of crushed glass, metal dust, and one or more organic solvents. Where appropriate, further additives, such as crystalline inorganic materials, are included. Preferred organic solvents or organic suspension agents are low-viscosity, high-boiling-point liquid organic materials. Advantageously, the boiling point is at least 120°C, and particularly preferably at least 180°C. The viscosity at 20°C is preferably less than 5 mPa·s. Various glycol ethers are particularly preferred.

[0046] It is particularly useful to use heavy metals or alloys with at least one heavy metal for the metal particles 23. Generally, it is preferable that the metal particles 23 contain at least 66 at% of metals with an atomic number greater than 55. According to an alternative or additional embodiment, the metal particles 23 contain at least 9 g / cm³ of metal to achieve good X-ray absorption. 3 It has a density such that, in particular, the density of the X-ray absorbing material 13 is preferably much higher than the density of the plate-like body 3. This results in very different X-ray absorption in different materials and, correspondingly, high contrast. Therefore, it is preferable that the density of the X-ray absorbing material 13 is at least four times that of the material of the plate-like body 3.

[0047] Particularly preferably, the X-ray absorbing material 13 contains particles of a tungsten-containing material, advantageously in the form of metallic tungsten or a tungsten alloy. Tungsten has a particularly high density. In its pure metallic form, tungsten has a density of 19.25 g / cm³. 3 It has a density of . Alternatively or additionally, it may contain particles of tungsten-containing minerals and / or tungsten-containing ceramics. High-density X-ray absorbing materials 13 can also be achieved by using heavy metals such as tungsten. Therefore, in one preferred embodiment, the X-ray absorbing material 13 has a density of at least 9 g / cm³. 3 , advantageously, at least 11 g / cm³ 3 It is provided that the material has a density of 8 g / cm³. In particular, such high densities can be achieved by combining heavy metal particles with glass, especially lead glass or solder glass. These densities are not uncommon even with respect to X-ray absorbing materials. For example, the density achieved by tungsten-containing plastics and polymer pastes is typically 8 g / cm³. 3 It is only slightly above that.

[0048] Furthermore, the thermal expansion coefficient of the X-ray absorbing material 13 can be adjusted by its components. By selecting these components and a suitable material for the plate-like body 3, particularly a suitable glass, according to another development of the shielding grating 1, the difference between the linear thermal expansion coefficient of the X-ray absorbing material 13 and the linear thermal expansion coefficient of the plate-like body 3 can be limited to less than 3 ppm / K. In order to match the expansion coefficients to each other, or at least reduce the difference between the expansion coefficient of the plate-like body and the expansion coefficient of the X-ray absorbing material, according to one embodiment, it is provided that the X-ray absorbing material contains at least one component having a linear thermal expansion coefficient of less than 1 ppm / K, or even negative, in at least a portion of the temperature range of 0°C to 200°C, advantageously in particulate form or as a granular additive for the formulation. The particles may, for example, be at least partially in the form of crystals. It is particularly advantageous here that there are also high-density materials that satisfy these conditions and therefore still have a good shielding effect. In particular, lead or tungsten compounds having such thermal expansion coefficients are known. In this advanced embodiment, the X-ray absorbing material 13 comprises at least one of a lead titanate and / or zirconium tungstate compound.

[0049] In yet another embodiment, the linear thermal expansion coefficients of the glass and metal particles 23 of the X-ray absorbing material 13 are also matched to each other. Advantageously, the glass and metal particles 23 are selected such that the difference in their linear thermal expansion coefficients is a maximum of 5 ppm / K. Below, an example of one embodiment of the components of the X-ray absorbing material 13 or the paste for manufacturing the X-ray absorbing material 13 is described. As the glass, G017-52 type solder glass containing lead oxide is used. This glass has a high lead content and a PbO content of 86% by weight. Tungsten metal particles are added as a further component. The properties and composition of the X-ray absorbing material manufactured therefrom are shown in the table below.

[0050] [Table 1]

[0051] As can be seen from this embodiment, by combining the materials, 9 g / cm³ 3 This is clearly higher than 11 g / cm³. 3 It is possible to achieve an even higher density, which is clearly superior to that.

[0052] Another glass suitable for use as an X-ray absorbing material is bismuth solder glass G018-423 from Schott-AG. This solder glass contains up to 84% by weight of Bi2O3.

[0053] One of the challenges in filling the trench 11 with a doctor blade as described above is that the trench 11 is very narrow and deep due to its high aspect ratio. Nevertheless, it is desirable that the trench 11 be as complete as possible. Furthermore, it is desirable that no holes are formed after the glass melts, or that they be as few and as small as possible. These properties can be surprisingly effectively influenced by the particle size of the material.

[0054] Figure 12 shows the particle size distribution of solder glass crushed with an attritor. One preferred type of glass is, in particular, solder glass G017-052 by the present applicant. The dashed curve is a histogram of glass particle diameters. The solid line shows the cumulative progression of particle size. Since glass particles are not spherical, the diameter shown on the horizontal axis of the graph represents the average value of the horizontal dimension. The glass powder has a 90% diameter of 1.39 μm. This is the maximum diameter that 90% of the glass particles have. The 50% diameter is 0.67 μm, and the 10% diameter is 0.24 μm. According to one development of the present method, it is provided that the components used, namely the glass powder and metal particles, are selected so as to maximize the packing density. Typically, this selection is made under the secondary condition of making the metal particle content as high as possible. Even under these secondary conditions and, if applicable, a predetermined particle size distribution, the packing density can be adjusted by adding two types of metal powders with different particle size distributions to a paste or, more generally, a mixture of glass particles and metal particles. The packing density can be optimized by different weights of the two powders and by considering the particle size distribution of the glass powder. According to one preferred embodiment, the packing density of the material 13 in the trench 11, which is packed and, if necessary, solidified by the melting or initial melting of the glass as described above, is at least 40 vol%, and preferably at least 60 vol%. Furthermore, a packing density of at least 70 vol% is targeted and achievable.

[0055] The degree of packing can be calculated, for example, using the Andreasen model. The Andreasen model assumes the following particle size distribution. F(d) = 100 × (d / d max ) n

[0056] Here, the function value F(d), which depends on the particle size, is the cumulative percentage of particles with a diameter of d or less. Therefore, the function value F(d) corresponds to the cumulative value Q3, or the solid line in the graph of Figure 12. The shape of the distribution is determined in particular by the constant n. Parameter d max This indicates the maximum diameter of the particles present.

[0057] Optimization can also be performed using other models known to those skilled in the art. Alternative models include, for example, the Ψ model or the Dinger function model.

[0058] Figure 13 shows the particle size distribution according to one embodiment. In particular, in addition to the particle size distribution of the crushed glass shown in Figure 12, two particle size distributions for tungsten metal powders B10 and B20 are shown, as well as the particle size distribution for a mixture of all three components, i.e., a mixture of crushed glass and both metal powders. The particle size distribution can be characterized in particular by its d50 value, which is the value at which the number of large particles is equal to the number of small particles. In other words, half of the total particles of each dust or crushed material have a diameter smaller than the d50 value. The d50 value of metal powder B10 is 3 μm, the d50 value of metal powder B20 is 5 μm, and the d50 value of crushed glass is only 0.67 μm. Metal powders B10 and B20 are supplied by Allied Material Co., Ltd. (Japan).

[0059] As can be seen from Figure 13, the glass has the smallest particle size, and the metal powder B20 has the largest particle size. Therefore, according to one embodiment, at least three components, namely the crushed glass and both metal powders, are mixed to obtain the highest possible packing density. Accordingly, according to one evolutionary form, the method generally includes the steps of measuring or calculating the packing density of a mixture of crushed glass (or glass dust) and at least one further powder; calculating and / or further measuring the packing density of the mixture; calculating or measuring the packing density of the mixture at least once with varying mixing ratios; selecting or determining the mixing ratio of a formulation for filling the trench 11 from at least two of the results of the calculation or measurement; and manufacturing the formulation of that mixing ratio. However, the selected mixing ratio for the formulation does not have to be the same as one of the measured or calculated mixing ratios. Thus, an ideal mixing ratio can also be interpolated or extrapolated from the results.

[0060] The particle size distribution of the mixture of glass powder and both metal powders B10 and B20, optimized with respect to packing density, is between the particle sizes of the metal powders and the glass dust. According to one embodiment, the formulation has the following mixture.

[0061] [Table 2]

[0062] Therefore, tungsten metal particles constitute a weight percentage slightly over 80 weight percent and a volume percentage of approximately 30 volume percent.

[0063] Minerals or ceramics containing heavy elements, particularly heavy metals, may be used instead of, or in addition to, metal particles. Heavy elements are understood to be elements with an atomic number greater than 55, according to the definition above. Here again, the X-ray absorbing material is preferably a material that contains at least 10% by weight of elements with an atomic number of at least Z=56, and at least 25% by weight, particularly preferably at least 50% by weight, of such elements with Z≧56, even if metal particles are not additionally included. Suitable minerals are particularly scheelite or calcium tungstate (CaWO4), lead oxide, and lead sulfide.

[0064] When the mixture packed into the trench 11 is heated, the glass melts or softens, and thus a solid matrix for the metal particles 23 is formed, the glass particles as a whole are no longer detectable on the completed shielding grating. However, the fact that the metal particles 23 have a wide size distribution due to being a mixture of two types of metal dust with different fineness is a characteristic of a preferred mixture having a high packing density, and consequently a characteristic of the X-ray absorbing material 13 having a high absorption efficiency. Therefore, generally, although not limited to the examples described above, X-ray absorbing materials 13 are provided in which the particles fixed to the glass are advantageously present in the form of a mixture of at least two powders with different d50 values, particularly a mixture of metal powder and / or mineral powder and / or ceramic powder. In particular, these d50 values ​​may differ by at least about 1.5 μm, as in the embodiment. This mixture also has the fact that it has a relatively wide particle size distribution, at least much wider than the particle size distribution of the two metal dusts obtained individually. When the Andreazen distribution according to the above formula is applied to such a real distribution, a relatively small exponent n is obtained. Therefore, according to one developmental form, the particles, preferably metal particles 23, and the Andreasen distribution F(d) = 100 × (d / d) is adapted to the particle size distribution of the metal particles 23. max ) n An X-ray absorbing material 13 is provided, which includes an index (or modulus) n of n having a particle size distribution less than n=0.33, and preferably less than n=0.28, where d max is the maximum particle size of the fitted Andreasen distribution. The Andreasen distribution is idealized and fitted to the actual distribution of metal particles 23, so d max The values ​​do not need to match the actual maximum particle size of the metal particles 23. In the log-log display of Figure 13, the Andreasen distribution is a straight line, not a curve like the particle size distribution actually shown.

[0065] Using two types of metal powders with different fineness levels may not only broaden the particle size distribution. According to an alternative or additional embodiment, the particle size distribution of particles in the X-ray absorbing material 13, particularly the metal particles 23, may be bimodal or multimodal. This means that in a particle size distribution illustration, such as the one shown for the crushed glass in Figure 12, the histogram has two or more distinguishable maxima.

[0066] In addition to tungsten dust, other components may be present in particulate form. For example, additives that can adjust the thermal expansion coefficient of the X-ray absorbing material, such as low-expansion materials, or even components with negative thermal expansion, such as lead titanate or zirconium tungstate, are considered. By introducing trenches 11 and wells, most of the material of the plate-like body 3 is removed. In particular, the continuous connection of the material of the plate-like body 3, as seen in embodiments of Figures 2, 8, and 9, may extend in a meandering manner rather than linearly due to this structuring. This reduces the stability of the plate-like body 3. The strength can be increased again by fixing the material of a solid X-ray absorbing material 13, such as provided in the form of molten glass or solder glass 21. Nevertheless, it may be desirable to give the structured plate-like body 3 higher strength. One way to do this is to connect the plate-like body 3 to a further plate-like body. In this case, advantageously, a glass plate can be connected to the plate-like body 3. In particular, a thin glass plate can be used for this. In this regard, Figure 14 shows an example of this embodiment. In one modification, as shown in the figure, a thin glass plate 8 is attached to the second surface 7 of the plate-like body 3. The advantage of this arrangement is that the well 15 is additionally sealed, thus preventing impurities from entering or contaminating the well 15. In the spirit of this disclosure, the thin glass plate 8 is understood to be a glass plate having a thickness of up to 250 μm, and preferably up to 150 μm. Thin glass is particularly suitable in this case because the material thickness is small and X-ray absorption is minimal. At the same time, even with thin glass, the mechanical stability of the arrangement is considerably improved, which is particularly advantageous because the well 15 typically has only a small width or lateral width. As a result, the thin glass can hardly bend on the well 15, and a significant increase in rigidity is achieved. The same applies to the thin glass plate 8 attached to the first surface 5 of the plate-like body 3. Therefore, in general, although not limited to the illustrated examples, one embodiment provides that a thin glass plate 8 is attached to at least one of the surfaces 5, 7 of the plate-like body 3. Several methods are suitable for attachment.A simple variation involves using adhesives such as epoxy resin or silicone. Alternatively, solder glass, such as the same solder glass used in the X-ray absorbing material 13, could be used. Connecting with solder glass allows for the attachment of the thin glass plate 8 to the plate-like body 3 and the melting of the solder glass in the X-ray absorbing material 13 to be performed in a single step. Similarly, the two plate-like bodies 3 and 8 can be welded together with a laser. Anode bonding is also a possibility.

[0067] One alternative or additional further processing of the shielding grid 1 is, for example, the application or sealing of an organic layer by immersion. An example relating to this is shown in Figure 15. In this example, the plate-like body 3 of the shielding grid 1 is completely surrounded by an organic sealant 10. The sealant 10 can also completely or at least partially fill the wells 15, as shown. Provided that the organic material does not exhibit high X-ray absorption, this does not result in significant absorption loss in the wells 15. Suitable organic sealants include polymers, lacquers, synthetic resins, and silicones. Unlike in the illustration, the organic sealant 10 may be applied to only a portion of the plate-like body 3, for example, only the first surface 5. Thus, in general, this embodiment provides that the organic sealant 10 is applied to at least a portion of the plate-like body 3, or to at least a portion of the surface of the plate-like body 3. This embodiment can, of course, be combined with an embodiment having a thin plate glass 8. In this case, the organic sealant 10 can function as a mechanical protector for, for example, a plate-like body 3, particularly a thin glass plate 8.

[0068] Various embodiments for filling the trenches 11 of the plate-like body 3 with an X-ray absorbing material are described below. Figures 16 to 19 show the process steps according to the first embodiment. For simplification, only one section of the plate-like body 3 having a single trench 11 is illustrated. To facilitate filling, it is preferable to degas the cavity or trench 11. Next, as shown in Figure 16, a dispersion 57 containing metal particles 23 and a dispersion medium 59 is filled into the trench 11. The dispersion 57 is sometimes collectively referred to as a paste according to the embodiments described above. In addition to the metal particles 23 already described, the dispersion may also contain other particles, such as glass particles.

[0069] To ensure proper filling of the trench 11, the filling is preferably carried out under pressure. In the next step, the dispersion 57 is dried, in which case the dispersion medium 59 is removed. This causes the particles to settle and become denser. However, as a result, the trench 11 may not be completely filled, as shown in Figure 17. Therefore, to achieve the highest possible degree of filling, the process of filling the dispersion as shown in Figure 18 and drying or removal of the dispersion medium as shown in Figure 19 can be repeated one or more times. Ideally, this would achieve complete filling of the trench 11 with the particles of the dispersion, as shown in Figure 19. Therefore, according to one embodiment, the following method is provided, although not limited to the specific examples shown in Figures 16 to 19: - The step of filling a trench 11 of a plate-shaped body 3, which is advantageously stored in a reduced-pressure environment, particularly in a vacuum, with a dispersion 57 having a dispersion medium 59 and metal particles 23, - A step of removing the dispersion medium 59 to settle the metal particles 23, - A step in which these two steps are repeated at least once to gain an advantage.

[0070] However, in some cases, voids may still exist in the filling of the trench 11. To solve this problem, it is also possible to manufacture a compound containing further metal to fill the gaps between particles, instead of or in addition to the highest possible compaction of the metal particles 23 in the trench 11. In this regard, Figures 20 to 23 show process steps for filling according to a further embodiment of the manufacturing method. First, the trench 11 is filled with metal particles 23, as shown in Figure 20. Here, this filling can also be carried out according to the method described in Figures 16 to 19. Next, as shown in Figure 22, a filler material 60 is placed on the surface 5 of the plate-like body 3. Then, it is melted and flows into the trench 11 to fill the gaps between the metal particles 23. The result is shown in Figure 23. The filler material 60 is generally advantageous in that its melting point is equal to the glass transformation temperature T g The filler material is selected to be less than the melting point of the metal particles 23. Furthermore, it is desirable that there be sufficiently high X-ray absorption in order to improve the X-ray contrast when a shielding grating is used. Therefore, according to another development, the filler material is selected to have at least half the X-ray absorption of tungsten. Thus, low-melting-point metals or alloys, such as those containing tin and / or lead, are particularly suitable for the filler material. The melting point of the filler material 60 is advantageously less than 300°C. Such properties are particularly satisfied by solder.

[0071] Good wettability of the metal particles 23 is advantageous for allowing the filler material 60 to flow into the gap. In this regard, according to one development, a coating 230 is provided on the metal particles 23, as shown in Figure 21. In this regard, for better wettability, the coating 230 can have a higher surface energy than the surface of the metal particles 23. If tungsten or a tungsten-containing alloy is used for the metal particles 23, good wettability can be obtained even without the coating 230 because the metal particles 23 already have a very high surface energy. In the illustration in Figure 23, it is shown that some of the filler material 60 remains on the surface of surface 5. This filler material 60 on the surface can be removed, for example, by polishing. If this metal film is very thin, it may be left as needed. Furthermore, the surface of surface 5 can be polished to facilitate the removal of the filler material 60 from the surface or to avoid wetting.

[0072] Furthermore, a flux may be added to the filler material 60 or metal particles 23 to improve wettability. In general, the X-ray absorbing material 13 containing metal particles 23 embedded in the filler material 60 is obtained by the method according to Figures 20-23. In general, the embodiments described with reference to Figures 20-23 can further result in one or more of the following features of the X-ray absorbing material 13: - The filler material has a melting point lower than that of the metal particles 23, and the glass transformation temperature T of the plate-like body 3 is lower than that of the filler material. g It has a lower melting point. - Regardless of whether the metal particles 23 are embedded in the filler material 60, the metal particles 23 of the X-ray absorbing material 13 can have a coating 230 having a higher surface energy than the material of the metal particles 23. Such a coating 230 can also serve to improve the fluidity of the metal particles 23. This development may be particularly advantageous in relation to the embodiments shown in Figures 16-19. Silaneized metal particles 23 are particularly suitable for this. Thus, according to another development, the X-ray absorbing material 13 is provided to include silaneized metal particles 23. Such a coating can be deposited in a plasma using, for example, a CVD process. Other surface modifications can also be achieved in a plasma. Thus, according to one development of the method, the X-ray absorbing material 13 containing metal particles 23 is provided to be filled into a trench 11, and the surface of the metal particles 23 is modified with plasma. The modification can be performed before filling, or after filling if necessary.

[0073] A process step according to a further embodiment will be described with reference to Figures 24 and 25, in which the gaps can be filled or closed during filling.

[0074] First, as shown in Figure 20, metal particles 23 are packed into the trench 11. Next, as shown in Figure 24, a metal ink 62 is packed in, filling the gaps between the metal particles 23. When the metal ink 62 dries, as shown in Figure 25, the metal ink 62 leaves a metal or metal-containing coating 230 on the metal particles 23 and the walls of the trench 11. To achieve the highest possible density of packing, this process can be repeated one or more times as needed. As the metal for the coating 230, a material with high X-ray absorption is suitable in this case as well. In general, regardless of the layer deposition process, in this regard, according to one embodiment, the trench 11 is provided to be packed with an X-ray absorbing material 13 containing metal particles 23 having an X-ray absorbing coating 230. This is particularly to which the above criteria for X-ray absorbing materials according to this disclosure apply, namely, a material having an X-ray absorption coefficient for X-rays with an energy of 69.5 keV that is at least three times that of the X-ray absorption coefficient of the plate material, and / or a material having a density at least four times that of the plate material, and / or a material having at least 10% by weight of an element having an atomic number of at least Z=56.

[0075] One further method for depositing the X-ray absorbing coating 230 onto the metal particles 23 and the walls of the trench 11 is atomic layer deposition (ALD), also known as ALD. In this method, various gaseous precursors are introduced alternately and reacted with the surface to deposit very thin layers, and even single atomic layers. A significant advantage is that this method can also deposit tungsten coatings. For this purpose, it is known to use B2H6 or SiH4 in combination with WF6 as a precursor. Yet another method for depositing the X-ray absorbing coating 230 and, consequently, filling at least partially, the gaps between the metal particles 23 is immersion coating, and electroplating, for example, to produce ITO or AZO films. Thus, in general, various embodiments of the methods described with reference to Figures 24 and 25 provide for filling the trench 11 with metal particles 23 and then applying the X-ray absorbing coating 230 to the metal particles 23 after filling. These method variations can also be combined with other methods described herein for filling the trench 11, such as filling with a glass powder-containing paste. Thus, it is also possible to coat the trench with metal particles after the paste has dried, and to combine different methods layer by layer so that the trench 11 has X-ray absorbing material of different configurations at different depths. This combination capability also applies to the method variations described below.

[0076] Figures 26 and 27 show a further embodiment of a method for filling the trench 11 with metal particles. In this embodiment, metal powders 232 and 233 with different particle sizes and shapes are sequentially filled into the trench. First, as shown in Figure 26, the trench is filled with metal powder 232 having spherical metal particles 231. The spherical metal particles 231 are advantageously relatively large, leaving large gaps between them. Such spherical metal particles 231 are used, for example, in 3D printing. The spherical shape helps to provide high fluidity during 3D printing, and in turn, helps to provide the possibility of forming a very thin layer of loose particles on the object to be printed by removal. Thus, this high fluidity also enables easy filling of the trench 11. Metal powders for 3D printing having spherical or at least nearly spherical metal particles 231 are usually produced by atomization. This utilizes a gas or liquid jet, typically a water jet, which divides the molten metal flow into very small droplets. The at least substantially spherical shape of the particles 231, as provided according to this embodiment, results particularly from the atomization process described above. In the second step, as shown in Figure 27, a metal powder 233 is added, having metal particles 23 that are significantly smaller than the spherical metal particles 231. These smaller metal particles can effectively fill the large gaps between the spherical metal particles 231. Contrary to the illustration, the smaller metal particles of the later-added metal powder 233 may also be spherical. This is also preferable due to the good fluidity of such particles.

[0077] While not limited to specific examples, referring to the embodiments shown in Figures 26 and 27, a shielding grid 1 having at least one of the following features is provided: - The X-ray absorbing material contains spherical metal particles 231. - The X-ray absorbing material comprises two types of metal powders that differ in particle size with respect to the metal particles 23, 231, in which case the average particle size differs by at least twice, and the larger metal particles 23 are spherical. Thus, the X-ray absorbing material 13 as a whole has at least a bimodal particle size distribution with two maxima. In this case, the corresponding manufacturing method includes the step of filling the trench 11 with the X-ray absorbing material 13 by filling it with a first metal powder 232 having spherical metal particles 231, and then filling it with a second metal powder 233, characterized in that the metal particles 23 of the second metal powder 233 have an average particle size smaller than the spherical metal particles 231 of the first metal powder 232. This embodiment, like the other embodiments described herein with respect to the filling of the trench 11, is independent of how the trench 11 is formed in the plate-like body 3.

[0078] Figures 28 to 30 show another embodiment for filling the trench 11. This embodiment can also be combined with other filling methods, such as the two-stage filling shown in Figures 26 and 27. In embodiments described with reference to Figures 28 to 30, a paste or dispersion 57 is flowed into the trench, during which metal particles 23 are allowed to settle or accumulate in the trench 11 as they flow. To enable this type of filling, one development of the plate-like body 3 is provided in which each of the trenches 11 has a bottom opening 110. This is a modification of the embodiment already described above, in which the trenches 11 are open at least partially on both sides 5,7 of the plate-like body 3.

[0079] For filling, a paste or dispersion 57 with a high proportion of dispersion medium 59 is poured into the trench 11 so that the dispersion medium 59 reappears at the bottom opening 110, as shown in Figure 28. At least some of the metal particles 23 are too large to reach the bottom opening 110. This blocks the bottom opening 110, allowing only the dispersion medium 59 to pass through the opening, while metal particles 23, such as tungsten particles, are filtered out and remain in the trench 11. In some cases, still very small particles may first pass through the barrier of the bottom opening 110. This state is shown in Figure 29. This flow continues until the cavity or trench 11 is sufficiently filled. The trench 11 thus filled is shown in Figure 30. Although not limited to the specific examples shown in Figures 28 to 30, in this regard, according to one embodiment of the present method, the trench 11 of the plate-like body 3 is provided with a bottom opening 110, the cross-section of which is smaller than the cross-section of the trench 11, and by flowing a dispersion 57 containing metal particles 23 into the trench 11, the dispersion medium 59 of the dispersion 57 flows out at the bottom opening 110 and the metal particles 23 settle at the bottom opening 110, thereby blocking the passage for further metal particles 23, and the trench is filled by further flowing the dispersion 57 to settle the metal particles.

[0080] It will be apparent to those skilled in the art that the present invention is not limited to specific embodiments as shown in the drawings, but can be varied in various ways within the scope of this disclosure. In particular, various embodiments can be combined with each other. For example, the dispersion 57 in Figures 26 to 30 is illustrated to contain only metal particles 23. The dispersion 57 may contain other particles, such as glass particles, as in the paste embodiments described above. After filling, these can then be melted as described above, thereby solidifying the X-ray absorbing material 13 in the trench 11 and firmly connecting it to the trench 11. This manufacturing method can also be used in devices other than the X-ray mask described herein, particularly with respect to filling the trench 11. For example, the array of radiation absorbing trenches can also be used in optical devices such as, for example, a two-dimensionally extended light guide. In such cases, it is not necessary that the filling material of the trench 11 be X-ray absorbing. Radiation absorption that matches the spectral distribution of radiation can be present. If necessary, other properties such as high permeability of the material in the trench can also be present. Thus, according to another embodiment, it is provided that at least some of the metal particles may be ferromagnetic. This can be used, for example, for selective induction heating. Therefore, in general, a further embodiment provides a method for manufacturing an element having an array of trenches 11, particularly a grid of intersecting trenches, comprising the following steps already described above: - The steps of providing a plate-like body 3 having a first surface 5 and a second surface 7 facing the first surface 5; manufacturing an array of trenches 11 opening toward the first surface 5; and filling the trenches 11 with a radiation-absorbing material, the filling being done using a dispersion or paste having metal particles 23 in particular. With respect to shielding grates, and especially with respect to manufacturing methods, the shape and dimensions of the trenches 11, the filling of the trenches, for example, solidification by melting solder glass, and the filling material, the entire disclosure described herein is also applicable to such other elements having an array of trenches 11.

[0081] The following describes an embodiment for introducing diagonally extending trenches 11 and wells 15 into a plate-like body 3, supplementing the explanation of Figure 6. Figure 31 shows a part of a laser processing apparatus for introducing filamentous damage into a plate-like body, as an advanced form of the embodiment in Figure 6. Advantageously, and not limited to the illustrated example, a laser beam 40 is directed towards the plate-like body 3 via a rotating mirror 46. It is particularly preferable to provide an additional polarizing mirror 47 so that the laser 51 emits light perpendicular to the plate-like body 3, as in the example in Figure 6. Two rotating devices, preferably turntables 48 and 49, represented by circles, are provided to rotate the rotating mirror 46 and the focusing optical system 52. These rotating devices are arranged coaxially with each other so that their rotational axes coincide. The rotating mirror 46 is located on one of the rotating devices, for example, the turntable 48. The other rotating device, i.e., the turntable 49, rotates the focusing optical system, preferably including a lens 520, as in the example in Figure 6. To direct the laser beam at a predetermined angle Θ onto the plate-like body, the focusing unit 52 is rotated by this angle on the turntable 49, while the rotating mirror 46 is rotated by half this angle in the same direction on the turntable 48. These two rotations can be coupled mechanically or even electronically. Furthermore, as shown in the example in Figure 6, the point of incidence onto the plate-like body 3 can be adjusted using a positioning unit 53, which is not shown in Figure 31 for simplification.

[0082] In one embodiment, the (focusing) lens 520 is biconvex and has large spherical aberration, or the entire imaging optical system has large spherical aberration. This creates a long focal point in the shape of the focal line. The lens 520 may also be aspherical accordingly, or even formed as an axicon lens. In one modification, the lateral intensity profile of the laser beam 40 is further formed such that the laser beam 40 has a lateral "top shape" profile, i.e., the 1 / e of the laser beam. 2Over a distance of 70%, preferably 80%, and particularly preferably 85% of the beam diameter, the deviation of intensity from the average intensity in this range is less than 30%, preferably less than 25%, preferably less than 20%, and particularly preferably less than 10%. In one further embodiment, the intensity along the long focal line formed by the focusing lens 520 is also distributed in a "top shape" along the optical axis with the parameters described above. The turntable 49 can be rotated in an angular range of -40° to +90° with respect to the perpendicular incidence direction. The focal length of the focusing optical system 52, particularly the lens 520, is in the range of 8mm to 30mm, preferably 10mm to 24mm, and its center in the focal point or direction of the light ray is within the plate-like body 3. The beam diameter before focusing is in the range of 8mm to 18mm, preferably 12mm. According to one embodiment, the processing of the glass plate-like body 3 is carried out with the following parameters: the wavelength is in the range of 1000 nm to 1100 nm, and optionally, particularly by doubling the frequency, a wavelength in the range of 500 nm to 600 nm can be selected. The pulse duration is in the range of 0.3 ps to 10 ps. The repetition frequency of the laser pulse is 30 kHz to 100 kHz. The laser is operated in burst mode with 1 to 8 pulses per burst, preferably 2 to 4 pulses. The pulse energy is in the range of 5 μJ to 500 mJ, preferably in the range of 50 μJ to 50 mJ, and particularly preferably in the range of 100 μJ to 10 mJ. The plate-like body 3 is scanned at a speed of 100 mm / s to 500 mm / s, depending on the geometric shape to be manufactured. The preferred interval for filamentous damage or modification is in the range of 2 μm to 20 μm, preferably in the range of 3 μm to 10 μm.

[0083] After introducing filamentous damage or modification, the plate-like body 3 is subjected to an etching process to create trenches 11 and wells 15. If necessary, further heat treatment can be performed before etching to relieve stress on the material. This annealing is performed at a glass transition temperature T g The range, especially slightly above it, for example, T gThe process is carried out at +20°C. For example, if the glass transition temperature is 525°C, the heat treatment temperature is 545°C. The plate-like material 3 is then exposed to an acidic or preferably alkaline etching medium, particularly a KOH solution. Here, the KOH concentration is in the range of 4 mol / l to 22 mol / l, favorably in the range of 12 mol / l to 18 mol / l. Etching is carried out at a temperature of 60°C to 100°C. This achieves an etching rate of less than 0.5 μm per hour to 8 μm per hour. The duration of the etching process to produce trenches 11 and wells 15 is generally 2 to 12 hours, typically 4 to 8 hours. The etching process can be assisted by ultrasonic stirring. [Explanation of symbols]

[0084] 1 shielding grid 2 X-ray imaging device 3. Plate-like body 5.3 First face 7 3's second face 8 Thin plate glass 9 lattice 10 Organic sealant 11 Trench 12 channels 13 X-ray absorbing materials 15 wells 16 15 bottom wall 17 15 central axis 18 Point source 19 The wall between 11 and 15 21 Solder glass 23 Metal particles 25 11 wall 27 Edge region of 1 30 x-ray tube 31 Anode 32 Cathode 33 Vacuum valve 34 Object 35 X-ray 36 Scattered X-rays 39 Detectors 40 Laser beams 41. Filamentous damage 43 Filamentous injury 41 First group 44 Filamentous injury 41, second group 45 Etching medium 46 Rotating Mirror 47 Polarized Mirror 48,49 Turntable 50 Laser processing equipment 51. Ultrashort pulse lasers 52 Focusing optical system 53 Positioning Unit 54 40 Incidence Point 55 arithmetic units 57 Dispersion 59 Dispersion medium 60 Filler metal 62 Metallic Ink Bottom opening in 110 11 230 Coating 231 Spherical metal particles 232,233 Metal powder 520 lens 521 Telescope Tube

Claims

1. A shielding grid (1) against scattered ionizing radiation, particularly for an X-ray imaging device, comprising: - a plate-like body (3) having a first surface (5) and a second surface (7) opposite to said first surface (5); The plate-like body (3) comprises: - has an array of wells (15) opening towards the second face (7) of the plate (3), - said plate (3) has a grid (9) made up of trenches (11) opening towards said first face (5); - said trenches (11) are filled with an X-ray absorbing material (13); a shield grid (1) in which the trenches (11) extend between the wells (15) at a distance from the wells (15) when viewed from one side (5, 7) so that walls (19) remain between the wells and the trenches (11).

2. 2. The shielding grid (1) according to claim 1, wherein the plate-shaped bodies are formed as glass panes.

3. Features include: the depth to width ratio of said trenches (11) is at least 40:1; - the depth of the trench is at least 1.5 millimeters; the deviation of the angle of the walls (25) of the trench (11) or well from the target angle, in particular from the direction of the central axis (17), is less than 5°; the center-to-center distance between two adjacent trenches is less than their depth, advantageously by a factor of three or less; - the width of the trench (11) differs from the width of the well (15) by a factor of at most two, the width of the trench (11) is at most 100 μm, preferably at most 50 μm; Shielding grid (1) according to claim 1, characterized by at least one of the following:

4. Shielding grid (1) according to claim 1, wherein the central axes (17) of the wells (15) and / or the trenches (11) are directed towards a common virtual point source (18).

5. Features include: - said X-ray absorbing material (13) comprises an incipiently melted or molten glass; - said X-ray absorbing material (13) comprises a lead and / or bismuth-containing glass; - said X-ray absorbing material (13) comprises particles, in particular metal particles (23) and / or mineral particles and / or ceramic particles, embedded in an incipiently molten or molten material, advantageously glass; - the X-ray absorbing material (13) has a density of at least 9 g / cm3, advantageously at least 11 g / cm3; the density of said X-ray absorbing material (13) is at least four times the density of the material of said plate (3); - the X-ray absorbing material (13) comprises at least 10% by weight, advantageously at least 25% by weight, of elements with an atomic number of at least Z=56; - said X-ray absorbing material (13) comprises particles of a tungsten-containing material, advantageously in the form of metallic tungsten, a tungsten alloy and / or a tungsten-containing mineral and / or a tungsten-containing ceramic, the difference between the linear thermal expansion coefficient of the X-ray absorbing material (13) and the linear thermal expansion coefficient of the material of the plate-shaped body (3) is less than 3 ppm / K; the filling degree of the X-ray absorbing material (13) in the trenches (11) is at least 40% by volume, advantageously at least 60% by volume; the glass of the X-ray absorbing material (13) has a glass transition temperature Tg that is at least 160° C., preferably at least 220° C. lower than the glass transition temperature Tg of the glass of the plate 3; the glass of the X-ray absorbing material (13) has a processing temperature at a viscosity of 10 dPa·s of the glass that is at least 100° C. lower than the processing temperature of the glass of the platelet (3); the glass of the X-ray absorbing material (13) has a processing temperature lower than the softening point of the glass of the plate-shaped body (3), the softening point being determined by a viscosity of 107.6 dPa s; - said X-ray absorbing material (13) comprises at least one component in particulate form that has a linear thermal expansion coefficient of less than 1 ppm / K or negative in at least part of the temperature range from 0°C to 200°C; Shielding grid (1) according to claim 1, characterized by at least one of the following:

6. Features include: the trench (11) is at least partially open on both sides (5, 7) of the plate (3); - said trench (11) has a bottom opening (110) Shielding grid (1) according to claim 1, characterized by at least one of the following:

7. Features include: - the X-ray absorbing material (13) comprises particles in the form of a mixture of at least two powders, in particular metal and / or mineral and / or ceramic powders, with different d50 values, the X-ray absorbing material (13) comprises particles having an Andreasen distribution F(d)=100×(d / dmax)n of particle diameters d adapted to the particle size distribution of the metal particles (23), the exponent n being smaller than n=0.33, advantageously smaller than n=0.28, where dmax is the maximum particle diameter of the adapted Andreasen distribution; the particle size distribution of the particles in the X-ray absorbing material (13) is bimodal or multimodal, the X-ray absorbing material (13) comprises metal particles (23) embedded in a filler metal (60), the filler metal (60) having a melting point lower than the melting point of the metal particles (23) and lower than the transformation temperature Tg of the glass of the plate-shaped body (3); the X-ray absorbing material (13) comprises metal particles (23) having a coating (230) which advantageously has a higher surface energy or absorbs X-rays than the material of the metal particles (23); - said X-ray absorbing material (13) comprises silanized metal particles 23; The X-ray absorbing material includes spherical metal particles 231. - the X-ray absorbing material comprises two metal powders which differ with respect to the size of the metal particles (23, 231), the average particle size differing by at least a factor of two, the larger metal particles (23) being spherical; Shielding grid (1) according to claim 1, characterized by at least one of the following:

8. Features include: - a thin glass sheet (8) is attached to at least one face (5, 7) of the plate-like body (3); - an organic sealing material (10) is applied to at least a part of the surface of the plate-like body (3); Shielding grid (1) according to claim 1, characterized by at least one of the following:

9. 10. An X-ray imaging device, in particular a computed tomography device (2), comprising an X-ray source and a shielding grid (1) according to any one of claims 1 to 8, arranged in front of an X-ray detector (39) for detecting X-rays emitted from the X-ray source.

10. 9. A method for producing a shielding grating (1) against scattered X-rays according to any one of claims 1 to 8, comprising: - providing a plate-like body (3) having a first surface (5) and a second surface (7) opposite said first surface (5); - irradiating said plate (3) with a laser beam (40), the material of which is transparent to said laser beam (40), so that said laser beam (40) penetrates said plate (3), - the laser beam (40) leaving filamentary damages (41) along a path of the laser beam (40) through the plate (3), the filamentary damages (41) being introduced such that a first group (43) of the filamentary damages (41) terminate at the first surface (5) and a second group (44) of the filamentary damages (41) terminate at the second surface (7); - removing material of the platelet (3) in the region of the first and second groups (43, 44) of filamentary damages (41) by etching the platelet (3) with an etching medium (45), - by removing material in the area of ​​the second group (44), an array of wells (15) is formed that are open towards the second face (7) of the plate (3); - removing material in the areas of said first group (43) so as to form a grid (9) made up of trenches (11) opening towards said first face (5); then - filling said trenches (11) with an X-ray absorbing material (13); A method comprising:

11. 11. The method according to claim 10, further comprising filling the trench (11) with powdered glass, preferably solder glass (21) as a component of the X-ray absorbing material (13), preferably a mixture of powdered glass and particles, and melting or incipiently melting the solder glass (21) to form a strong X-ray absorbing material (13) that adheres to the walls of the trench (11).

12. 11. The method according to claim 10, wherein the filamentary damage (41) is introduced at least partially obliquely with respect to one of the faces (5, 7) of the plate-like body (3).

13. 11. The method according to claim 10, wherein at least some, preferably both groups (43, 44) of the filamentous lesions terminate within the plate (3).

14. 11. The method of claim 10, wherein the laser beam is irradiated onto the same surface of the plate and the position of the focus of the laser beam relative to the plate is changed to form at least some of the filamentary damages of both groups in a direction along the laser beam.

15. 11. The method of claim 10, further comprising providing a paste containing glass particles and metal particles (23), filling the trenches (11) with the paste, and heating the plate (3) to soften the glass particles, thereby obtaining an X-ray absorbing material (13) having particles embedded in glass.

16. - measuring or calculating the packing density of the mixture of ground glass and at least one further powder; - calculating or measuring the packing density of said mixture; - calculating or measuring at least once the packing density of the mixtures with varying mixing ratios; - selecting or determining the mixing ratio of the formulations for filling said trenches (11) from at least two results of the calculations or measurements; - preparing a formulation of said mixture ratio; 11. The method of claim 10, comprising:

17. The method of claim 10, further comprising filling the trenches (11) with metal particles (23) and applying an X-ray absorbing coating (230) to the metal particles (23) after said filling.

18. 11. The method of claim 10, wherein filling the trench (11) with the X-ray absorbing material (13) comprises filling a first metal powder (232) having spherical metal particles (231) and then filling a second metal powder (233), wherein the metal particles (231) of the second metal powder (233) have an average particle size smaller than the spherical metal particles (231) of the first metal powder (232).

19. 11. The method according to claim 10, wherein the trenches (11) of the plate-shaped body (3) have bottom openings (110), the cross section of each of the bottom openings (110) being smaller than the cross section of the trenches (11), and wherein flowing a dispersion (57) containing metal particles (23) into the trenches (11) causes a dispersion medium (59) of the dispersion (57) to flow out at the bottom openings (110) and the metal particles (23) to settle at the bottom openings (110), thereby blocking the passage of further metal particles (23), and the trenches (11) are filled by further flowing the dispersion (57) to settle the metal particles (23).

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