Tiled anti-scatter grid for selective transmission of radiation
By designing controlled distances between modules and adding pixel materials in the anti-scattering grid, the manufacturing challenge of large-area anti-scattering grids was solved, achieving high performance and stable radiation transmission effects.
Patent Information
- Application Number
- CN202480059645.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-09-20
- Filing Date
- 2024-09-10
- Publication Date
- 2026-04-14
AI Technical Summary
When manufacturing large-area, high-performance anti-scattering grids for selective transmission of radiation, it is difficult to uniformly determine and position thin and tall wall structures across the entire area, resulting in low manufacturing yield and risks of image artifacts and structural instability.
The design employs an anti-scattering grid that includes a first module and a second module. The sides of the modules are separated by a certain distance in the tiling direction, with an average distance less than 200% of the grid pitch. Solid or semi-solid pixel materials are added between the modules to enhance stability and modulate radiation absorption.
It reduces interference from radiation scattering distribution, improves the performance of anti-scattering grids, increases the manufacturing yield of large-area grids, and provides smooth radiation transmission characteristics and structural stability.
Smart Images
Figure CN121866629A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to an antiscattering grid for selective transmission of radiation. Specifically, the invention relates to an antiscattering grid comprising a first module and a second module tiled together. The invention also relates to an imaging component comprising an antiscattering grid for selective transmission of radiation, and an imaging system comprising such an imaging component. Background Technology
[0002] Fabricating high-performance antiscattering gratings with large surface areas for selective transmission of radiation (such as X-ray antiscattering gratings for advanced X-ray imaging systems) is challenging because it requires determining and positioning the dimensions of thin, tall wall structures uniformly and consistently across the entire area. For example, when fabricating antiscattering gratings using 3D printing, there are often limitations on the size of the manufacturing platform that can be used. Therefore, for large-area structures, such as those larger than 20 x 20 cm... 2 Anti-scattering grids can have low manufacturing yields. One option to mitigate this challenge is to fabricate smaller grid tiles and then merge (tile) multiple such small grid tiles to form a larger structure. However, the interfaces between adjacent grid tiles can cause image artifacts, as well as structural instability and breakage risks. Therefore, improvements in this manufacturing process are needed. Summary of the Invention
[0003] The object of this invention is to provide an improved tiling of an anti-scattering grid for selective transmission of radiation.
[0004] This invention is defined by the independent claims. Advantageous embodiments are defined in the dependent claims.
[0005] According to a first aspect of the invention, an anti-scattering grid for selective transmission of radiation is provided. The anti-scattering grid includes a first module and a second module. Each of the first and second modules includes a plurality of walls having a height, wherein for each of the first and second modules, these walls form a plurality of repeating grid cells having a defined pitch. The first and second modules are tiled together in a tiling direction transverse to the height of the walls, such that a side of the first module faces an adjacent side of the second module along a longitudinal direction transverse to both the tiling direction and the height. For each coordinate along the longitudinal direction facing the adjacent side of the second module from the side of the first module, the side and the adjacent side are separated by a tiling distance in the tiling direction. The average of all tiling distances between the side and the adjacent side along the longitudinal direction is greater than zero and less than 200% of the pitch. Preferably, the average of all tiling distances is greater than zero and less than 100% of the pitch.
[0006] Because of the non-zero average distance between the sides of the modules of the anti-scattering grid, compared to a tiled structure where, for example, the modules are placed in contact with each other such that the distance is essentially zero, interference with the radiation scattering profile of the tiled structure can be reduced and performance improved. This is because the proposed anti-scattering grid avoids the "double walls" from the combined modules.
[0007] In the context of this invention, the grid pitch p is the minimum distance between the centers of adjacent repeating grid cells. A grid cell may also be referred to as a pixel. This grid pitch is preferably (substantially) the same over the region of each module, and preferably (substantially) the same for all modules that together form a tiled antiscattering grid. When modules are tiled together to form an antiscattering grid, the scattering distribution of the antiscattering grid for selective transmission of radiation is improved compared to the case where the average distance would be larger, by keeping the average distance between adjacent modules less than 200% (preferably less than 100%) of the grid pitch p.
[0008] Modules may have sides that are straight in at least one direction or may have other shapes. For example, in the case of a module with hexagonal pixels, the sides of the module may form a zigzag pattern in the vertical direction. Modules may also be referred to as tiled sheets. Anti-scattering grids may include more than two modules. A module may be tiled together with multiple other modules in multiple tiling directions.
[0009] The longitudinal direction *l* and the tiling direction *t* transverse to *l* can be said to form a coordinate system. Along the interface between two adjacent modules, the tiling distance *td* can be determined at multiple discrete points (such as multiple equidistant points) along the longitudinal direction *l*, i.e., the distance between the sides of adjacent modules in the tiling direction. Then, the average tiling distance *td_avg* is the sum of the discrete tiling distances *td* divided by the number of tiling distances.
[0010] According to one embodiment of the invention, the tiling distance is constant along the longitudinal direction. In other words, the corresponding tiling distance is the same as the average tiling distance. This method of tiling modules together to form a tiling anti-scattering grid is referred to in this disclosure as a "controlled gap pattern" and enables, for example, anti-scattering grids with good performance.
[0011] According to another embodiment of the invention, the tiling distance is not constant along the longitudinal direction, and the tiling distance is less than 0.1p in at least one coordinate along the longitudinal direction. This method of tiling modules together can be an advantageous alternative to the aforementioned "controlled distance". In this case, the modules are very close to each other (less than 0.1 pitch) in at least one coordinate. The modules can contact each other such that the minimum distance is locally zero or very close to zero. This tiling method is referred to in this disclosure as a "kissing pixel pattern". Advantageously, the tiling distance is less than 0.1p in multiple evenly distributed coordinates along the longitudinal direction. This provides a consistent scattering distribution along the longitudinal direction.
[0012] According to one embodiment of the invention, the average value of all tiling distances is greater than 0.1p and less than 0.5p. This narrower choice of average tiling distance can further improve the radiation transmission characteristics of the anti-scattering grid. For example, when the anti-scattering grid is included in an anti-scattering grid.
[0013] According to one embodiment of the present invention, the grid cells between the walls comprise solid or semi-solid pixel material, and the density of the pixel material is less than 10 g / cm³. 3 Preferably less than 5 g / cm 3 More preferably less than 3 g / cm 3 Adding solid or semi-solid pixel material between the walls of the grid cells can provide additional stability to the structure without interfering with the selective radiation transmission of the anti-scattering grid. Furthermore, the choice of material can be used to precisely modulate radiation absorption, such as X-ray or gamma-ray absorption. Pixel materials can advantageously include at least one of aluminum, glass, cotton fibers, adhesives, aerogels, foams, carbon, or paper.
[0014] According to one embodiment of the present invention, the space between the side of the first module and the adjacent side of the second module comprises a solid or semi-solid paving material, and the density of the paving material is less than 10 g / cm³. 3 Preferably less than 5 g / cm 3 And more preferably less than 3 g / cm 3Solid or semi-solid material in the gaps (one or more) between two modules laid together can increase the structural stability of the anti-scattering grid. This material can be used as an adhesive to hold the modules together. The material can provide damping to reduce the risk of structural damage to any module when they are laid together. By selecting the material, radiation absorption, such as X-ray or gamma-ray absorption, in one or more gaps between the modules can be precisely modulated. The tiling material can be freely applied between the modules. Alternatively or additionally, the tiling material can be applied to one or both modules before they are laid together. The tiling material may advantageously include at least one of aluminum, glass, cotton fibers, adhesive, aerogel, foam, carbon, or paper.
[0015] According to one embodiment of the invention, for each module, the wall extends in the tiling direction, and for each module, the grid cells are repeated only in the longitudinal direction to form a one-dimensional grid. In this way, a tiling large-area one-dimensional grid with good scattering distribution can be manufactured, such as an anti-scattering grid.
[0016] According to one embodiment of the invention, for each module, grid cells are repeated in both the tiling and longitudinal directions to form a two-dimensional grid. In this way, large-area tiling two-dimensional grids with good scattering distribution, such as anti-scattering grids, can be manufactured. Advantageously, the grid cells have a hexagonal shape. The hexagonal pixel shape provides higher anti-scattering performance than square (or rectangular) pixels at constant grid ratio, partition thickness, grid height, and pixel pitch. Hexagonal pixels reduce the amount of material required, for example, for 3D printing of the grid, and enhance mechanical stability compared to, for example, square pixels.
[0017] According to one embodiment of the invention, each of the first and second modules has a hexagonal external shape. Hexagonal modules (such as hexagonal modules with hexagonal pixels) can advantageously provide an anti-scattering grid with a smooth scattering distribution and high mechanical stability.
[0018] According to a second aspect of the invention, an imaging component is provided comprising an anti-scattering grating as described above. The imaging component includes at least one of an X-ray or gamma-ray anti-scattering device, an X-ray or gamma-ray filter, an X-ray or gamma-ray collimator, or an X-ray or gamma-ray grating.
[0019] According to a third aspect of the present invention, an imaging system including the imaging component is provided.
[0020] These and other aspects of the invention will become apparent from the embodiments described below and will be set forth with reference to the embodiments described below. Attached Figure Description
[0021] Figure 1AAn example of a one-dimensional grid is shown schematically.
[0022] Figure 1B An example of a two-dimensional grid is shown schematically.
[0023] Figure 2-4 An example of a tiled anti-scattering grid is shown schematically.
[0024] Figure 5-7 The calculated scattering distribution of the tiled anti-scattering grid is shown. Detailed Implementation
[0025] Figure 1A and Figure 1B Examples of a one-dimensional (1D) grid 100-A and a two-dimensional (2D) grid 100-B are shown respectively. The grid can be a (monolithic) anti-scattering grid, such as an X-ray anti-scattering grid having walls made of tungsten or another suitable X-ray absorbing material. Each of the grids 100-A and 100-B includes a partition wall 102 having a defined width w and height h. Pixels 104 for selectively transmitting radiation (such as X-ray radiation) are formed between the dense partition walls 102. Pixels are repeated with a pixel pitch p. In the case of the 1D grid 100-A, pixels are repeated in one dimension, and in the case of the 2D grid 100-B, pixels are repeated in two dimensions. The pixel pitch p in the first and second dimensions can be the same or different. Examples of the range of anti-scattering grid design parameters can be: grid pitch p = 0.1-2 mm, partition wall thickness w = 20-100 μm, and grid height h = 2-10 mm. The grid ratio R, defined as R = h / (pw), typically varies between 4 and 20, but other configurations are possible. For high-performance anti-scattering grids, the aspect ratio of the partitions (which is the ratio between its height and its thickness) is usually high, such as between 10 and 100.
[0026] The size of the high-quality focusing grid required in medical flat panel detector applications can range from, for example, 10 x 10 cm in one or two dimensions. 2 The grid size has been expanded to be greater than 1m. Manufacturing a grid with a large surface area requires accurately determining and positioning the dimensions of thin and tall partition structures uniformly across the entire area.
[0027] This disclosure provides a robust and reliable solution for achieving composite large-area grids by joining multiple grid tiles together. Most medical image processing methods for scatter suppression and / or scatter correction rely on the fact that changes in scattering levels occur only gradually, i.e., scattering is a low-frequency signal. Therefore, sudden (high-frequency) changes in the scattering signal caused by grid tile boundaries are avoided. Scattering simulations of different positioning geometries of grid tiles in a large-area anti-scattering grid assembly have shown that image artifacts, for example, at grid tile boundaries caused by double walls, can be effectively reduced by introducing a controlled (average) distance between the tiles and (optionally) a spacer material.
[0028] Figure 2 An example of a tiled anti-scattering grid from a rectangular grid tile with hexagonal grid pixels is shown. A first grid module (or tile) 11 is tiled next to a second grid module 12 in the tiling direction t, as indicated by the arrow. As a result, the side 110 of the first grid module 11 is positioned adjacent to the side 120 of the second grid module 12. As can be seen from the right-hand portion of the module in the figure, the sides of the adjacent modules are separated by an average tiling distance td_avg along the longitudinal direction of the interface between the two modules in the tiling direction t.
[0029] like Figure 2 As shown, grid tiles with hexagonal grid pixels are joined together without forming double walls, thereby introducing controlled small gaps between the tiles. In this example, due to the rectangular shape of the grid tiles, the tiling distance td between the partitions forming the corresponding sides of adjacent tiles is uniform along the longitudinal direction l, but not along the tiling direction t.
[0030] Figure 3 An example of a tiled anti-scattering grid formed by hexagonal modules with hexagonal grid pixels is shown. In this case, due to the hexagonal structure of the modules, the gap between adjacent sides can remain constant along all six sides of the module surrounded by other modules. In this way, a smooth and uniform scattering distribution can be achieved.
[0031] Figure 4 An example of a tiled anti-scattering grid formed by hexagonal modules with hexagonal grid pixels is also shown. This structure is similar to... Figure 3 The difference in the anti-scattering grid is that, in Figure 4 In this model, modules are tiled in a "kissing pixel pattern," where adjacent modules have partial side contact or are very close to each other (less than 0.1p). Diamond-shaped grid pixels are formed at the interface between two modules, and triangular grid pixels are formed at the intersection of three modules. Figure 3Compared to controlled gaps, from a manufacturing perspective, laying the modules flat together is simpler.
[0032] exist Figures 5 to 7 The image shown is a calculated X-ray image of a 100 mm thick water plate model positioned in a simple X-ray setup between a 120 kV tungsten anode X-ray tube and a 154 μm pixel flat-panel X-ray detector. The distance between the tube and the detector is 105 cm. The specific grid of interest is positioned 15 mm from the detector's imaging plane. The simulated 2D grid is a 3D-printed air-spaced tungsten grid with a pixel pitch of 1.5 mm, a grid ratio of 6, and a septum thickness of 100 μm. The simulated 1D grid is a glass-spaced lead grid with a grid pitch of 227 μm, a grid ratio of 12, and a septum thickness of 30 μm. Monte Carlo simulations were performed in two consecutive steps. First, an X-ray photon database was generated in the simulation tool by bombarding the water plate model with billions of X-ray photons emitted from the X-ray focus of the tube. Secondly, another simulation tool takes all relevant design parameters of the specific grid as input, and then bombards the grid with each photon from the photon database generated in the first step. As a result, the 2x2 cm detector is determined to be... 2 The number of primary transmitted photons and scattered transmitted photons captured in the central region.
[0033] Figure 5 Examples of two modules 11 and 12 with hexagonal pixels are shown. From left to right, the figure shows a schematic grid module structure (left), a simulated scattered X-ray image captured by the detector (top center), a simulated primary X-ray transmission image of the interface between modules (bottom center), and a simulated scattering distribution along the cross-section line A-A' (right). The modules are tiled together at a controlled distance between the sides of the modules. In this figure, the tiling direction is between A and A'. The tiling distance td along the longitudinal direction l is constant. The tiling distance td along the longitudinal direction l is the same as the average value td_avg. Figure 5 The diagram shows that when 2D grid tiles with hexagonal pixels are joined together in a controlled gap pattern with a tile spacing td of approximately 200 μm, the scattering distribution at the tile boundaries is only slightly disturbed. As the tile spacing increases, the scattering distribution becomes more distorted (not shown in the figure). This effect can be partially prevented by filling the gaps with low X-ray absorbing materials such as adhesives, aerogels, foams, carbon, paper, cotton fibers, aluminum, or glass.
[0034] Figure 6 With Figure 5A similar approach demonstrates that when hexagonal 2D grid modules with hexagonal tiles are joined together in a kissing pixel pattern such that the edges of the modules contact at uniformly distributed points along the longitudinal direction, the scattering distribution at the boundaries of the tiles is only slightly disturbed. If the distance between the partitions of the "kissing pixels" at the edges of the tiles increases, the scattering distribution becomes visually distorted (not shown in the figure). This can be partially prevented by filling the air gaps with low X-ray absorbing materials such as glue, aerogel, foam, carbon, paper, cotton fibers, aluminum, or glass.
[0035] Figure 7 A tiling of “tandem” 1D grid modules is shown, where the partitions (in this case, lead sheets) in adjacent modules are positioned in a straight line. Simulations show that the scattering distribution at the boundaries of these modules is only slightly sensitive to the gap width between the tiling sheets and the material of the gap spacers, but to a lesser degree than when the modules are tiled with the walls “parallel” (not shown in the figure). Similarly, in this case, distortion of the scattering distribution can be reduced by filling the air gaps between the tiling sheets with a low X-ray absorption material. Furthermore, the scattering distribution is only slightly affected by the lateral displacement of the modules in a direction perpendicular to the sheet walls.
[0036] The results shown in the example above demonstrate that multiple small grid tiles can be combined to form a high-performance composite large-area anti-scattering grid, such as those larger than 20 x 20 cm. 2 Compared to manufacturing single large-area grids, the manufacturing yield of this composite tiled grid can be higher.
[0037] The grid tiles preferably provide complete tiling of the XL grid surface area. The size of gaps or other "ineffective areas" between grid tiles is minimized to avoid degradation of anti-scattering performance near the edges of the grid tiles. For 2D grids, grid pixels with square (rectangular) or hexagonal shapes that provide complete tiling are found to have the best anti-scattering performance. Complete tiling structures can also be obtained by combining different polygons (e.g., octagons and squares) in the grid pixels, but these designs may offer limited advantages at the cost of increased design complexity. Grid pixels and grid tiles can be configured in a manner where a "unit design" can be repeatedly used to achieve composite XL grids. This unit-cell approach is preferred to reduce the complexity of designing and manufacturing all the required (different) small grid tiles and to facilitate the assembly of the final XL grid. The use of mechanically robust grid tiles is preferred to minimize manufacturing yield losses due to physical damage during tile production and subsequent processing and fabrication. The septum thickness is preferably small (≤100µm), preferably smaller than the pixel size of the X-ray detector, so as to minimize the risk of losing relevant clinical information or low-pixel signals in the acquired X-ray images due to shadowing effects.
[0038] The previous examples demonstrated how to avoid double septa to minimize image artifacts. Furthermore, the boundaries between grid tiles provide a smooth distribution of X-ray scattering. Most medical image processing methods used for scatter suppression and / or scatter correction rely on the fact that changes in scattering levels occur only gradually, i.e., scattering is a low-frequency signal. Therefore, sudden (high-frequency) changes in the scattering signal caused by grid tile boundaries should be avoided.
[0039] As an example, tungsten hexagonal 2D grid tiles composed of hexagonal grid pixels enable the assembly of tiled composite 2DXL grids with controlled gaps (or "kissing pixel pattern") between the tiles. These 2DXL grids offer improved anti-scattering performance, smooth X-ray scattering distribution, low tungsten weight, and enhanced mechanical robustness.
[0040] It should be noted that the above embodiments are illustrative of the invention and not limiting of it, and those skilled in the art will be able to devise many alternative embodiments without departing from the scope of the appended claims. As an example, in the above figures, the 2D grid is shown as having hexagonal pixels, but many other shapes can also implement the invention. For example, square pixels, rectangular pixels, etc.
[0041] In the claims, any reference numerals placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements other than those listed in the claims. The words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements. In an apparatus claim enumerating several means, several of these means may be embodied in the same hardware. Measures recited in mutually different dependent claims may be advantageously combined.
Claims
1. An anti-scattering grid (10) for selective transmission of radiation, the anti-scattering grid (10) comprising a first module (11) and a second module (12). in, Each of the first module (11) and the second module (12) includes a plurality of walls having a height (h). In each of the first module (11) and the second module (12), the wall forms a plurality of repeating grid cells with a grid pitch (p). The first module (11) and the second module (12) are laid together in a tiling direction (t) transverse to the height (h) of the wall, such that the side (110) of the first module faces the adjacent side (120) of the second module in a longitudinal direction (l) transverse to the tiling direction (t) and the height (h). Wherein, for each coordinate in the longitudinal direction (l) along the side (110) of the first module facing the adjacent side (120) of the second module, the side (110) and the adjacent side (120) are separated by a tiling distance (td) in the tiling direction (t), and Wherein, the average value (td_avg) of all the tiling distances (td) between the side (110) and the adjacent side (120) along the longitudinal direction (l) is greater than zero and less than 200% of the grid pitch (p), preferably greater than zero and less than 100% of the grid pitch.
2. The anti-scattering grid according to claim 1, wherein, The tiling distance (td) is constant along the longitudinal direction (l).
3. The anti-scattering grid according to claim 1, wherein, The tiling distance (td) is not constant along the longitudinal direction (l), and in at least one coordinate along the longitudinal direction (l), the tiling distance (td) is less than 10% of the grid pitch (p).
4. The anti-scattering grid according to claim 3, wherein, In a plurality of uniformly distributed coordinates along the longitudinal direction (l), the tiling distance (td) is less than 10% of the grid pitch (p).
5. The anti-scattering grid according to any one of the preceding claims, wherein, The average value (td_avg) of all the tiling distances (td) is greater than 10% and less than 50% of the grid pitch (p).
6. The anti-scattering grid according to any one of the preceding claims, wherein, The grid cells between the walls comprise solid or semi-solid pixel material, and the density of the pixel material is less than 10 g / cm³. 3 Preferably less than 5 g / cm 3 And more preferably less than 3 g / cm 3 .
7. The anti-scattering grid according to claim 6, wherein, The unit material includes at least one of aluminum, glass, cotton fiber, adhesive, aerogel, foam, carbon, or paper.
8. The anti-scattering grid according to any one of the preceding claims, wherein, The space between the side (110) of the first module (11) and the adjacent side (120) of the second module (12) comprises a solid or semi-solid paving material, and the density of the paving material is less than 10 g / cm³. 3 Preferably less than 5 g / cm 3 And more preferably less than 3g / cm 3 .
9. The anti-scattering grid according to claim 6, wherein, The tiling material includes at least one of aluminum, glass, cotton fiber, adhesive, aerogel, foam, carbon, or paper.
10. The anti-scattering grid according to any one of the preceding claims, wherein, For each module (11, 12), the wall extends in the tiling direction (t), and for each module (11, 12), the grid cell repeats only in the longitudinal direction (l) to form a one-dimensional grid.
11. The anti-scattering grid according to any one of claims 1-9, wherein, For each module (11, 12), the grid cell is repeated in the tiling direction (t) and the longitudinal direction (l) to form a two-dimensional grid.
12. The anti-scattering grid according to claim 11, wherein, Each of the grid cells has a hexagonal shape.
13. The anti-scattering grid according to any one of the preceding claims, wherein, Each of the first module (11) and the second module (12) has a hexagonal external shape.
14. An imaging component comprising an anti-scattering grid according to any one of the preceding claims.
15. An imaging system comprising the imaging component according to claim 14.