Filter plate for metal foil filter, metal foil filter and CT machine

Abstract

The utility model discloses a filter plate for a metal foil filter, the metal foil filter and a CT machine. The length direction of the filter is formed by cutting the foil parallel to the axial direction of the roller, and the foil is formed by rolling of the roller. According to the utility model, the roller with the same roundness requirement can provide a filter with higher quality, the cost is reduced, and the yield is high.

Description

[0001] Nouns and pronouns relating to persons in this patent application are not limited to a specific gender. Technical Field

[0002] The utility model relates to a CT machine, in particular to a metal foil filter thereof. Background Art

[0003] Flat filters are often used to improve beam quality or obtain the spectrum required for CT. Some filters are partly cut from foils that are manufactured using a rolling process. Due to the roundness error of the roller and the inherent properties of the repeated rolling process, periodic and non-periodic thickness variations will occur in the direction of roller movement. It will cause periodic and non-periodic attenuation fluctuations in this direction. Figure 1 The figure is a schematic diagram of the attenuation of each row of gold foil filters in the channel direction in the prior art. If the amplitude of the attenuation fluctuation reaches a certain level, it may cause artifacts in the image. Therefore, the failure rate of the current process method is high.

[0004] When cutting long and narrow filters from foil, the current method is to cut the filter parallel to the direction of roller movement. The traditional improvement method is to control the roundness error of the roller. However, since the filter has very high requirements for absolute thickness and thickness change rate, measuring and controlling the roundness of the roller will bring very high costs and operational difficulties. And due to the inherent properties of the rolling process, the thickness of the start / end section of the foil in the direction of roller movement cannot be well controlled. Therefore, when the foil processed by the current method is used for filters, it may cause artifacts in the image. This will inevitably increase costs and affect the yield rate. Utility Model Content

[0005] In view of this, the utility model provides a filter sheet for a metal foil filter, a metal foil filter, and a CT machine.

[0006] According to a first aspect of the utility model, a filter sheet for a metal foil filter is provided, wherein the length direction of the filter sheet is parallel to the axial direction of a roller and is formed by cutting the foil sheet, and the foil sheet is rolled by the roller.

[0007] In one embodiment, the diameter of the roller is not less than 45 mm.

[0008] In one embodiment, the distance between the edge of the filter and the edge of the foil in a direction parallel to the axial direction of the roller is not less than 15 mm.

[0009] In one embodiment, the distance between the edge of the filter and the edge of the foil in a direction perpendicular to the axial direction of the roller is not less than 1500 mm.

[0010] According to a second aspect of the utility model, a metal foil filter is provided, comprising a base and the filter plate described above.

[0011] According to a third aspect of the utility model, a CT machine is provided, characterized in that it includes the metal foil filter mentioned above.

[0012] The utility model can provide a higher quality filter sheet with a roller wheel having the same roundness requirement, thereby reducing costs and increasing the yield rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so that those skilled in the art will be more aware of the above and other features and advantages of the present invention. In the accompanying drawings:

[0014] Figure 1 It is a schematic diagram of the attenuation of each row of gold foil filters in the channel direction in the prior art.

[0015] Figure 2 It is a schematic diagram of a filter sheet for a metal foil filter according to an embodiment of the utility model.

[0016] Figure 3 Schematic diagram of rolled foil.

[0017] Figure 4 It is a schematic diagram of a metal foil filter according to an embodiment of the present utility model.

[0018] Figure 5 It is a schematic diagram of the attenuation of each row of metal foil filters in the channel direction according to an embodiment of the present utility model.

[0019] In the above drawings, the reference numerals used are as follows:

[0020] 102 Foil

[0021] 104 Roller

[0022] 106 Filter

[0023] 108 Base

[0024] 110 Metal filter DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail with reference to the following embodiments.

[0026] When reconstructing an image, the original data is high-pass filtered in the channel direction, so the artifact is very sensitive to the attenuation fluctuation of the filter in the channel direction, but has a higher tolerance in the row direction. The utility model adjusts the cutting direction when cutting the filter from the foil, so that the cutting direction is perpendicular to the moving direction of the roller (roller) (parallel to the axial direction of the roller), thereby transferring the attenuation change from the channel direction to the row direction. Since the row length is shorter, the attenuation fluctuation in this direction will be relatively smaller.

[0027] Figure 2 FIG. 1 is a schematic diagram of a filter sheet 106 for a metal foil filter according to an embodiment of the present invention. Figure 2 As shown, the filter 106 is cut from the foil 102, and the foil 102 is rolled by the roller 104. The length direction of the filter 106 is parallel to the axial direction of the roller 104. The raw material of the foil 102 is a uniform, high-purity metal, such as 9999 gold. The thickness of the foil 102 can be, for example, 0.05 mm. In other embodiments, the foil 102 can also be made of metals such as tin. The thinner the metal foil, the more advantages of the utility model can be reflected, because for thicker metal foils, the change in attenuation is not obvious.

[0028] The larger the roller diameter, the longer the period, the smoother the attenuation fluctuation in the roller movement direction, and the smaller the impact on image quality. In order to reduce the impact of the attenuation fluctuation on the row direction, in one embodiment of the present utility model, the roller 104 has a larger diameter, for example, increased from 30 mm to 45 mm or more.

[0029] Due to the inherent properties of the rolling process, the thickness of the foil will vary at the edges. The difference perpendicular to the direction of roller movement is caused by the different pressures on the foil at different positions of the rollers. Figure 3 Schematic diagram of rolled foil 102. In order to mitigate this effect, the edge portion of foil 102 in this direction can be cut off (for example, 15 mm is cut off from each edge of 210 mm foil to achieve the required width of 180 mm). In other embodiments, more can be cut off. That is, the distance between the edge of filter 106 and the edge of foil 102 in the direction parallel to the axial direction of roller 104 is not less than 15 mm. The difference between the beginning and the end of the roller moving direction is due to the different roller molding (roller molding) of these two parts compared with other parts. To prevent this effect, the beginning and end portions (for example, about 1500 mm) can be cut off in this direction. In other embodiments, more can be cut off. That is, the distance between the edge of filter 106 and the edge of foil 102 in the direction perpendicular to the axial direction of roller 104 is not less than 1500 mm.

[0030] The filter 106 can be used to make a metal foil filter. Figure 4 Schematic diagram of a metal foil filter 110 according to an embodiment of the present invention. The metal foil filter 110 includes a base 108 and a filter sheet 106 , and the filter sheet 106 can be adhered to the base 108 . Figure 5 FIG. 1 is a schematic diagram of the attenuation of each row of the metal foil filter 110 in the channel direction according to an embodiment of the present utility model. Figure 5 As shown, the attenuation in the channel direction becomes more gradual, while the variation in the row direction can be ignored. The metal foil filter 110 can be used in a CT machine.

[0031] The utility model can provide a higher quality filter sheet with rollers of the same roundness, thereby reducing costs and increasing the yield rate.

[0032] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A filter sheet for a metal foil filter, characterized in that: The filter (106) is cut from a foil (102); the length direction of the filter (106) is parallel to the axial direction of the roller (104); and the foil (102) is rolled by the roller (104).

2. The filter according to claim 1, characterized in that: The diameter of the roller (104) is not less than 45 mm.

3. The filter according to claim 1, characterized in that: The distance between the edge of the filter (106) and the edge of the foil (102) in a direction parallel to the axial direction of the roller (104) is not less than 15 mm.

4. The filter according to claim 1, characterized in that: The distance between the edge of the filter (106) and the edge of the foil (102) in a direction perpendicular to the axial direction of the roller (104) is not less than 1500 mm.

5. A metal foil filter, characterized in that: include: Base (108); The filter (106) as claimed in any one of claims 1 to 4.

6. A CT machine, characterized in that: Comprising the metal foil filter as claimed in claim 5.

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