Device for calibrating an X-ray system, X-ray apparatus, and method for calibrating an X-ray apparatus.

Abstract

To provide a device (100) for calibrating an X-ray system (200) comprising an X-ray source (210) and an X-ray detector (220). [Solution] The calibration device (100) includes a set of at least two X-ray absorbing elements (1, 2), each element (1, 2) extending in the longitudinal (LO) and transverse (LA) directions. According to the present invention, the device (100) is configured to adjust the position of each element (1, 2) along a closed surface (C1, C2) in a plane extending transversely to the transverse (LA) and parallel to the longitudinal (LO) direction, such that the elements (1, 2) in each of the first and second subsets (10, 20) of the set of elements (1, 2) are positioned such that their longitudinal (LO) direction is aligned with the transverse alignment direction relative to the curved surface (C1, C2), characterized in that the first total length in the longitudinal (LO) direction of the elements (1, 2) of the first subset (10) is different from the second total length in the longitudinal (LO) direction of the elements (1, 2) of the second subset (20).

Description

Technical Field

[0001] The present invention relates to a device for calibrating an X-ray system comprising an X-ray source and an X-ray detector. This calibration device comprises a set of at least two X-ray absorption elements. Each element extends in the longitudinal and transverse directions. This calibration device is particularly suitable for calibrating an X-ray system in which an object to be inspected is transported along a transport path between the X-ray source and the X-ray detector. The present invention further relates to an X-ray apparatus comprising an X-ray system and a calibration device, and a method for calibrating the X-ray apparatus.

Background Art

[0002] X-ray systems have many applications including product inspection. For example, in the food industry, it is very important to reliably detect foreign objects in food. For this purpose, for example, by a belt conveyor, an object to be inspected can be transported along a transport path between the X-ray source and the X-ray detector of the X-ray system. The X-ray source creates a fan-shaped beam, and the X-ray detector is arranged to receive the X-ray beam and can be configured to output a signal according to the amount of received radiation. In this way, a two-dimensional X-ray image of the object to be inspected can be created. In the above example of food inspection, the X-ray image can make it possible to infer the presence of foreign objects in the food.

[0003] ,

[0004] (Lambert-Beer's law), is directly related to the distance x that the X-ray travels through the homogeneous body. Here, I0 is the intensity of the incident radiation, I is the intensity of the transmitted radiation, and b is the X-ray absorption coefficient depending on the material.

[0004] X-ray systems need to be calibrated periodically to ensure that the detector output signal accurately reflects the received radiation dose. This is due to the fact that the characteristics of the X-ray system, particularly the X-ray source and X-ray detector, can change over time. Furthermore, the characteristics of newly manufactured X-ray systems may not be fully understood. For example, an X-ray detector may contain a scintillation material that reacts to incident X-rays. This scintillation material may not be homogeneous. In addition, in the case of a line detector consisting of multiple individual detection elements, the detection elements may have slightly different characteristics, and therefore the detector may require calibration before use.

[0005] In a typical calibration process, a so-called phantom, an object with known absorption properties, is placed in the X-ray beam between the X-ray source and the X-ray detector. The detector's output signal for the phantom is recorded, and the X-ray system can be calibrated so that its output signal reliably indicates the amount of radiation that passed through the phantom. Some calibration processes require a phantom with spatially varying absorption properties for calibration purposes.

[0006] Various possible calibration devices (phantoms) are known in the art. Generally, calibration devices are adapted for calibrating specific types of X-ray systems. U.S. Patent No. 5,214,578 discloses a method for calibrating an X-ray system comprising an X-ray source and an X-ray detector. In this method, the X-ray detector is rotatable on an axis centered on the body under examination, and a circular phantom is positioned with its center offset from the rotation axis of the X-ray system. This calibration device is suitable for calibrating X-ray systems with a rotatable detector.

[0007] Japanese Patent No. 7102190 discloses a calibration device for an X-ray CT scanner. This calibration device comprises a plurality of concentric layers, where at least one of the composition and concentration of the material contained in each of the layers differs from one another at multiple rotation angles. The calibration device is scanned at multiple different rotation angles. This calibration device is suitable for calibrating an X-ray system based on scans at different rotation angles.

[0008] U.S. Patent No. 4,400,827 discloses a calibration device for calibrating rapid-sequence radiography. This calibration device comprises a disc in which multiple X-ray absorbing elements of different thicknesses perpendicular to the surface of the disc are arranged in a stepped manner along the circumference of the disc. The disc is rotated along a central axis perpendicular to its surface in synchronization with the cinematic imaging means of the cinematic radiography means, thereby changing the thickness of the X-ray absorbing material of the disc for each frame of cinematic radiography.

[0009] U.S. Patent No. 5,565,678 discloses a calibration target for an X-ray imaging system in which multiple X-ray absorption disks are stacked. This creates regions with different absorption characteristics in the radial direction.

[0010] EP 4 201 334 A1 discloses a calibration phantom for calibrating a CT imaging system. This calibration phantom comprises a base and a number of calibration wires distributed and connected to the base.

[0011] U.S. Patent Application Publication No. 2020 / 0261050(A1) discloses a calibration phantom for an X-ray imaging system in which a plurality of second and third objects are arranged around the periphery of a first central object. The first, second, and third materials are different from each other, so that at least one of the second and third objects is made of a second material and a third material, respectively. The calibration phantom moves through an X-ray path, and calibration is performed by determining the path length through the different materials of the phantom and generating a mapping between the path length and the detector response of an X-ray detector.

[0012] The calibration devices described above are not particularly suitable for calibrating X-ray systems in which the object to be inspected is transported along a transport path between the X-ray source and the X-ray detector. U.S. Patent Application Publication 2003 / 0072417(A1) and U.S. Patent No. 10,813,618(B2) each disclose a calibration device comprising multiple X-ray absorbing elements of different heights arranged in a stepped configuration. Different element heights result in different path lengths for the emitted X-rays. This calibration device is particularly suitable for X-ray systems comprising a fan beam and a line detector in which the object to be inspected is transported along a transport path between the X-ray source and the X-ray detector. Reliable calibration of an X-ray system requires passing the object through the X-ray system several times due to the unavoidable inaccuracies in positioning the calibration device. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] U.S. Patent No. 5,214,578 [Patent Document 2] Japanese Patent No. 7102190 [Patent Document 3] U.S. Patent No. 4,400,827 [Patent Document 4] U.S. Patent No. 5,565,678 [Patent Document 5] EP 4 201 334 A1 [Patent Document 6] U.S. Patent Application Publication No. 2020 / 0261050(A1) [Patent Document 7] U.S. Patent Application Publication No. 2003 / 0072417(A1) [Patent Document 8] U.S. Patent No. 10,813,618(B2) [Overview of the project]

[0014] Therefore, due to the problems of the prior art, the objective is to provide a calibration device for efficient and reliable calibration of X-ray systems, particularly X-ray systems in which an object to be inspected is transported along a transport path between an X-ray source and an X-ray detector. According to a first aspect of the present invention, this problem is solved by a device for calibrating the above type of X-ray system. The device is configured to adjust the position of each element along a closed surface in a plane extending transversely to the transverse direction and parallel to the longitudinal direction, such that the elements in each of the first and second subsets of the set of elements are positioned such that their longitudinal direction is aligned with the transverse direction relative to the surface, and the first longitudinal length of the elements of the first subset is different from the second longitudinal length of the elements of the second subset.

[0015] The term "closed surface" should be interpreted to also cover surfaces that extend between two turning points. Between these two turning points, the position of an element can be adjusted on the surface. In this case, the area enclosed within the surface becomes zero.

[0016] In the structure of the present invention, each of the two subsets corresponds to an aligned configuration of a number of absorbing elements corresponding to the number of elements in each subset. Adjusting the position of the aligned configurations allows each of their aligned directions to continuously coincide with the radiation beam path extending between the X-ray source and the X-ray detector. As a result, different configurations result in different absorption lengths of radiation passing through these configurations along their aligned directions.

[0017] Thus, the calibration device according to the first aspect of the present invention is configured such that the position of the X-ray absorption elements can be adjusted along a closed surface so that the moving distances of the X-ray beam moving through the aligned elements of the first and second subsets in the aligned direction are different from each other. Thus, in contrast to the prior art, there is no need to move the calibration device along the transport path between the X-ray source and the X-ray detector for calibration, although the calibration device may be stationary. In this way, efficient and reliable calibration can be performed. Furthermore, the calibration device can be widely applied to the calibration of X-ray devices. The calibration device can be assembled in a small and compact shape.

[0018] The calibration device includes a set of at least two X-ray absorption elements. Preferably, the calibration device includes three or more X-ray absorption elements. In one example, the elements of the set of elements may be made of the same material, but the present invention is not limited thereto. In one example, the material can be a polymer material. In one example, the material can be PE or PMMA, but the present invention is not limited thereto. In another example, the material can be a metal, such as aluminum or iron.

[0019] The longitudinal direction and the transverse direction are defined for each element. In particular, the transverse extensions of all the elements can be parallel to each other.

[0020] In one advantageous example, the transverse extension may be larger than the longitudinal extension of the element. In one example, the transverse extension can be the same for all elements. In one example, the transverse extension can be selected to be greater than or equal to the width of a typical X-ray detector used in the X-ray system to be calibrated, preferably at least 2%, 5%, or 10% larger than the width. In a further example, the element can have a cuboid shape.

[0021] In a further example, the plane can be the normal of the transverse extension of the element. In a further example, the longitudinal direction and the transverse direction can be orthogonal directions.

[0022] The first subset may include one or more elements. Further, the second subset may include one or more elements. The first and second subsets are different from each other. In particular, they are different by at least one element. However, in one example, they may be different by two or more elements or all elements.

[0023] In a further advantageous example, the calibration device is configured to be able to adjust the position of each element of the set of elements along a closed surface such that the elements in each of a plurality of different subsets of elements are positioned in a state where their longitudinal directions are aligned in an alignment direction transverse to the surface, and the total length in the longitudinal direction of the elements of each subset is different from the total length in the longitudinal direction of the elements of other subsets. The plurality of subsets may be three, four, or more subsets of elements. Thus, a plurality of different movement distances of the X-ray beam through the aligned elements of different subsets in the alignment direction can be created.

[0024] In an advantageous example, the alignment directions of two or more subsets of elements may be the same. This is particularly advantageous for an X-ray system equipped with an X-ray source configured to emit an X-ray beam in a fixed direction.

[0025] Each element has first and second longitudinal ends in the longitudinal direction, and the first and second longitudinal ends may move along the surface during adjustment.

[0026] The first longitudinal end may be located closer to the center of the surface than the second longitudinal end. In one example, one of the ends is located on the surface.

[0027] In one example, the alignment direction may be the normal direction of the surface. In one example, the surface is a convex surface.

[0028] According to another embodiment of the first aspect of the present invention, the surface may include a plurality of nested, non-intersecting surfaces, each element may be associated with one of the plurality of surfaces, and the device may be configured to adjust the position of each element along the associated surface, independently of the position of elements associated with other surfaces. According to the embodiment, the device may be configured to adjust the position of each element along an associated surface among a plurality of K≧2 surfaces. All surfaces lie in the same plane. Each surface has a different perimeter, and each surface is entirely located within the surface with the larger perimeter, except for the surface with the largest perimeter. In one example, the device may be configured to adjust the position of elements along two surfaces. In another example, the device may be configured to adjust the position of elements along three or more surfaces, for example, three, four, or five surfaces. According to the embodiment, the device may be configured to adjust the position of all elements associated with one surface simultaneously and independently of the position of elements associated with other surfaces. In one example, first and second subsets, and potentially further subsets of elements, may include elements associated with different surfaces of the plurality of surfaces. However, the present invention is not limited thereto, and the first and second subsets, and potentially further subsets of elements, may include only elements associated with the same surface.

[0029] In one embodiment, the calibration device may be configured to adjust the positions of elements associated with the same curved surface simultaneously, and in particular only simultaneously.

[0030] In further embodiments, the surface may be a concentric surface. The center of the concentric surface can be seen as the center of rotation. In further embodiments, the surface is circular. The longitudinal direction of the element may be the normal to the surface, and in one example, the alignment direction of the element may be the normal direction. The transverse direction of the element is perpendicular to the longitudinal direction and may be the normal to the plane of the surface.

[0031] In a further embodiment of the calibration device according to a first aspect of the present invention, at least two elements may have different longitudinal extensions. When the device is configured to allow the position of each element to be adjusted along a single closed surface, at least two elements on this single surface may have different longitudinal extensions. In this case, each of the first and second subsets may include one of at least two elements having different longitudinal extensions. When the device is configured to allow the position of each element to be adjusted along two or more closed surfaces, the positions of at least two elements having different longitudinal extensions may be adjustable on the same surface or on different surfaces.

[0032] In another example of the present invention, the device comprises at least three elements, two of which have the same longitudinal extension, and each of the first and second subsets includes one of two elements having the same longitudinal extension, and one of the two subsets includes a further element having the same or different longitudinal extension.

[0033] According to yet another embodiment of the calibration device according to the present invention, the elements may be separate elements. The distance between adjacent elements along the same curved surface may be the same or different for each pair of adjacent elements. In one example, at least some of the elements may be in contact at their first or second ends.

[0034] In a convenient example of the above embodiment, the device may be configured to adjust the position of elements so as to form a passage that extends straight across a curved surface and in which no elements are positioned. In this way, the device may function to adjust the position of elements along a closed curved surface so that an X-ray beam passes through the device without passing through any X-ray absorbing elements. In particular, in one example, the passage may extend in the alignment direction.

[0035] In a further embodiment of the calibration device according to a first aspect of the present invention, the first and / or second subset may include two elements associated with the same surface. For example, when the closed surface is circular and the longitudinal directions of the elements of the first and / or second subset are aligned with the normal to the surface, the two elements associated with the same surface are located opposite each other with respect to the surface. Thus, instead of a single element having a first length in the longitudinal direction, two elements having second and third lengths in the longitudinal direction may be provided opposite each other with respect to the surface. The sum of the second and third lengths is equal to the first length. This can reduce the overall height of the calibration device, which is advantageous because X-ray systems generally have limited space between the X-ray source and the X-ray detector.

[0036] According to yet another embodiment of the calibration device, the first and second side ends of an element may be attached to first and second supports spaced laterally apart, and the device may be configured to adjust the position of the element along a closed curved surface by allowing independent rotation of the first and second supports about a common axis extending laterally. In one example, the device may include a stepping motor configured to drive the first and second supports. The embodiment allows for a simple and constructive realization of adjusting the element along a curved surface. In this embodiment, the lateral length of all elements may be the same. In one preferred example, the first and second supports may be disc-shaped. However, the present invention is not limited thereto.

[0037] In yet another embodiment of the calibration device according to a first aspect of the present invention, each of the first and second supports may include a plurality of first and second segments, and the device may be configured to allow rotation of the first and second segments relative to each other so that elements associated with different curved surfaces can move relative to each other. In one example, the segments may have an annular shape, but the present invention is not limited thereto.

[0038] For calibration, the calibration device needs to be positioned between the X-ray source and the X-ray detector. Therefore, in another embodiment of the present invention, the device may include means for positioning the calibration device between the X-ray source and the X-ray detector on an X-ray system. In one example, the positioning means may include magnetic means. The magnetic means may be configured to interact with complementary magnetic means arranged within the X-ray system, thereby achieving the positioning of the calibration device. In another example, the positioning means may include a support frame.

[0039] In a further embodiment of the calibration device according to the present invention, the calibration device may include a stationary X-ray absorber positioned within a curved surface. The stationary X-ray absorber is not movable by the operation of the calibration device. Therefore, emitted X-rays passing through the calibration device can be absorbed regardless of the position of the elements along the curved surface.

[0040] According to a second aspect of the present invention, an X-ray apparatus is provided. This X-ray apparatus comprises an X-ray system having an X-ray source that emits an X-ray beam along a radiation path, and an X-ray detector that receives the X-ray beam and outputs a signal according to the amount of radiation received, and a calibration device according to any of the above, wherein the calibration device is positioned between the X-ray source and the X-ray detector such that the longitudinally extending portions of the elements of the first and second subsets are in the radiation plane along the radiation path of the X-ray beam when the longitudinal directions of the elements of the first and second subsets are aligned in the alignment direction, respectively. The X-ray apparatus according to the second aspect of the present invention enables calibration using a stationary calibration device, and different travel distances of the X-ray beam can be obtained by adjusting the position of the X-ray absorbing elements along one or more closed surfaces. The X-ray apparatus according to the second aspect of the present invention enables highly efficient and reliable calibration of the X-ray system.

[0041] In one embodiment, the X-ray apparatus may be configured to emit a fan-shaped X-ray beam into a radiating surface, and the X-ray detector may include a line detector positioned within the radiating surface to receive the radiation beam.

[0042] A third aspect of the present invention provides a method for calibrating the X-ray system of an X-ray apparatus according to a second embodiment. This method is The steps include adjusting the position of the elements of the calibration device to a first position so that the vertical direction of the elements of the first subset aligns with the alignment direction, After adjusting the elements to a first position, the X-ray source is operated to receive a first signal indicating the amount of radiation that has traveled through a first subset of the elements. The steps include adjusting the position of the elements of the calibration device to a second position so that the vertical direction of the elements of the second subset aligns with the alignment direction, After adjusting the elements to a second position, the X-ray device is operated to receive a second signal indicating the amount of radiation that has traveled through the second subset of elements. The procedure includes the step of calibrating the X-ray system based on first and second signals.

[0043] Since the absorption characteristics of the first and second subsets of elements are known, the X-ray system can be calibrated so that the output signal indicates the amount of radiation received. Preferably, the calibration device may include a plurality of subsets of elements with different longitudinal lengths, and the method may include adjusting the positions of the elements so that the aligned longitudinal directions of each subset of elements lie within the radiation plane.

[0044] In one embodiment, the method further includes: The steps include adjusting the position of the elements of the calibration device to the zero position so that there are no elements aligned in the alignment direction, The process includes the steps of adjusting the elements to the zero position, and then operating the X-ray device to receive a base signal indicating the maximum amount of radiation that has not traveled through any subset of the elements. The present invention will be described in detail below with reference to the following drawings. [Brief explanation of the drawing]

[0045] [Figure 1a]This is a perspective cross-sectional view of an X-ray apparatus according to a second aspect of the present invention, the X-ray apparatus comprising an X-ray system and a calibration device according to a first aspect of the present invention. [Figure 1b] This is an enlarged view of the portion of Figure 1a that shows the X-ray system and calibration device. [Figure 2] This is a side view of an element of a calibration device according to a first aspect of the present invention, with some parts of the element partially removed for ease of representation. [Figure 3a] This is a cross-sectional view showing different configurations obtained by operating the calibration device shown in Figure 2. [Figure 3b] This is a cross-sectional view showing different configurations obtained by operating the calibration device shown in Figure 2. [Modes for carrying out the invention]

[0046] Figure 1a is a perspective cross-sectional view of an embodiment of an X-ray apparatus 1000 according to a second aspect of the present invention. The X-ray apparatus 1000 comprises an X-ray system 200 and a calibration device 100 according to an embodiment of the first aspect of the present invention. The X-ray system 200 comprises an X-ray source 210, which emits a fan-shaped beam 211 into the radiation plane. The X-ray system 200 further comprises a line detector 220, which is an X-ray detector spaced perpendicularly from the X-ray source 210. The X-ray detector 220 may comprise a plurality of detection elements, for example having a scintillation material, that convert the incident emitted X-rays into electrical signals. The electrical signals are processed within the X-ray apparatus 1000, calibrated against a standard, and provide a measurement output indicating the amount of incident emitted X-rays. However, the calibration may change during use, and the X-ray apparatus 1000 may require recalibration. All of these can be achieved by using the calibration device 100, which is further described below.

[0047] The X-ray system 200 further includes a belt conveyor 230 configured to transport the object to be inspected along a transport path that is lateral to the radiation surface, specifically perpendicular to it.

[0048] Figure 1b is an enlarged view of a portion of Figure 1a showing the X-ray system 200 and the calibration device 100. As can be seen from Figure 1b, the calibration device 100 comprises multiple X-ray absorbing elements 1 and 2. The calibration device 100 is configured to allow adjustment of the positions of elements 1 and 2 so that selected elements 1 and 2 are within the radiating plane, as will be further described below.

[0049] The calibration device 100 further includes positioning means 40 configured to position the calibration device 100 between the X-ray source 210 and the X-ray detector 220.

[0050] Figure 2 is a perspective view of elements 1 and 2 of the calibration device 100 according to the embodiments shown in Figures 1a and 1b. Some of elements 1 and 2 have been partially removed for ease of representation. As can be seen from Figure 2, the calibration device 100 comprises a plurality of (inner) elements 1 associated with a first (inner) curved surface C1 (see Figures 3a to 3c) and a plurality of (outer) elements 2 associated with a second (outer) curved surface C2 (see Figures 3a to 3c). The calibration device 100 is configured to allow adjustment of the position of the inner elements 1 along the inner curved surface C1 and adjustment of the position of the outer elements 2 along the outer curve C2, independently of the inner elements 1. In this embodiment, the curved surfaces are circular concentric curved surfaces centered on a common axis A.

[0051] In this embodiment, elements 1 and 2 are rectangular parallelepipeds. Each element 1 and 2 has an extension in the vertical direction LO and an extension in the horizontal direction LA. The horizontal direction LA is parallel to the common axis A. The vertical direction LO is the normal to the curved surfaces C1 and C2.

[0052] The calibration device 100 is configured to adjust the position of each element along the associated curved surfaces C1 and C2 so that the longitudinal direction of elements 1 and 2 in each of the first and second subsets 10 and 20 of the set of elements aligns with the alignment direction, which is the normal to the curved surface, and the first total length in the longitudinal direction of elements 1 and 2 in the first subset 10 is different from the second total length in the longitudinal direction of elements 1 and 2 in the second subset 20. In particular, the positions of elements 1 and 2 can be adjusted so that when the longitudinal directions of elements 1 and 2 in the first and second subsets 10 and 20 are aligned with the alignment direction, the longitudinally extending portions of the elements in the first and second subsets are in the radiating plane along the X-ray beam radiation path R. This characteristic will be further explained with reference to Figures 3a to 3c.

[0053] Figures 3a to 3c show three different configurations of the calibration device 100 according to embodiments of the present invention. As can be seen from Figures 3a to 3c, each element 1, 2 has a distal end and a proximal end in the longitudinal direction LO. The proximal end is close to the common axis A, and the distal end is the end away from the common axis A. The calibration device 100 has six (inner) elements 1 associated with a first (inner) surface C1 (dashed line). The distal ends of the elements 1 associated with the first surface C1 move along the first surface C1 during adjustment of their positions along the first surface C1. Seven (outer) elements 2 are associated with a second (outer) surface C2 (dashed line). The proximal ends of the elements 2 associated with the second surface C2 move along the second surface C2 during adjustment of their positions along the second surface C2. Each closed surface C1, C2 has at least two elements 1, 2 associated with different longitudinal extensions.

[0054] Figure 3a shows the first configuration of the calibration device 100, which is the configuration shown in Figure 2. As can be seen from Figure 3a, the longitudinal LO of the three elements 1a, 2a, and 2b are aligned in the alignment direction AD, which is the normal to the closed surfaces C1 and C2. The X-ray beam radiation path R extends through elements 1 and 2 of the first and second subsets 10 and 20, along their aligned longitudinal LO. The three elements are those of the first subset 10, which consists of element 1a associated with the inner surface C1 and elements 2a and 2b associated with the outer surface C2. The longitudinal extension of element 1a is h1, the longitudinal extension of element 2a is h2, and the longitudinal extension of element 2b is h3. Therefore, the total length of elements 1a, 2a, and 2b in the longitudinal LO is h1 + h2 + h3. When the calibration device 100 is in its first configuration, the emitted X-rays from the X-ray source 210 travel through the three elements 1a, 2a, and 2b along a radiation path R parallel to the alignment direction AD, thereby traveling through the first total length of the X-ray absorbing elements 1a, 2a, and 2b in the longitudinal direction.

[0055] Figure 3b shows a second configuration of the calibration device 100 according to an embodiment of the present invention. The longitudinal LOs of the four elements 1b, 1c, 2c, and 2d of the second subset 200 are aligned in the alignment direction AD. The longitudinal extension LO of element 1b is H1, the longitudinal extension LO of element 1c is H2, the longitudinal extension of element 2c is H3, and the longitudinal extension of element 2d is H4. Elements 1b and 1c are associated with an inner curved surface C1, and elements 2c and 2d are associated with an outer curved surface C2. The second longitudinal length of elements 1b, 1c, 2c, and 2d is H1 + H2 + H3 + H4. As is clear from Figures 3a and 3b, the first longitudinal length and the second longitudinal length are different. When the emitted X-rays from the X-ray source 210 are released, the emitted X-rays travel along the radiation path R parallel to the alignment direction AD through the four elements 1b, 1c, 2c, and 2d, thereby traveling along the second full length of the X-ray absorbing element in the longitudinal direction.

[0056] Figure 3c shows a third configuration of the calibration device 100 according to an embodiment of the present invention. As can be seen from Figure 3c, there are no elements that intersect with the radiation path R of the emitted X-rays. Therefore, the emitted X-rays are not absorbed when they pass through the calibration device 100. [Explanation of Symbols]

[0057] 1, 1a, 1b, 1c Elements associated with the first closed surface 2, 2a, 2b, 2c, 2d Elements associated with the second closed surface 3. First side end 4. Second side end Elements of the first subset of 10 elements Elements of the second subset of 20 elements 30a, 30b First and second supports 31a, 31b First segment 32a, 32b Second segment 40 Position means 100 Calibration Devices 200 X-ray systems 210 X-ray source 211 Fan-shaped beam 220 X-ray detectors 230 Belt Conveyor 1000 X-ray equipment A Common axis C1 First curved surface C2 Second Curved Surface AD alignment direction LO (Vertical Direction) LA (Lateral Direction) R radiation path

Claims

1. A device (100) for calibrating an X-ray system (200) comprising an X-ray source (210) and an X-ray detector (220), wherein the calibration device (100) includes a set of at least two X-ray absorbing elements (1, 2), each element (1, 2) extending in the longitudinal (LO) direction and the transverse (LA) direction, wherein the device (100) has a closed surface (C) in a plane extending transversely to the transverse (LA) direction and parallel to the longitudinal (LO) direction. １ , C ２ The position of each element (1, 2) along the curved surface (C) is such that the elements (1, 2) in each of the first and second subsets (10, 20) of the set of elements (1, 2) correspond to each of the aligned configurations consisting of multiple absorbing elements, with the vertical direction (LO) of the element being the curved surface (C) １ , C ２ Device (100) is configured to be adjustable so as to be positioned in a lateral alignment direction relative to the first subset (10), wherein the first total length in the longitudinal direction (LO) of the elements (1, 2) of the first subset (10) is different from the second total length in the longitudinal direction (LO) of the elements (1, 2) of the second subset (20), and the adjustment of the position of the aligned configuration is characterized in that each of the aligned directions is made to coincide with a radiation beam path extending between the X-ray source (210) and the X-ray detector (220).

2. The curved surface (C １ , C ２ ) includes a plurality of nested non-intersecting curved surfaces (C １ , C ２ ) that extend horizontally with respect to the transverse direction (LA) and parallel to the longitudinal direction (LO) within the plane. Each element (1, 2) is associated with one of the plurality of curved surfaces (C １ , C ２ ). The device (100) is configured to adjust the position of each element (1, 2) along the associated curved surface (C １ , C ２ ) regardless of the position of the element (1, 2) associated with other curved surfaces (C １ , C ２ ). The device (100) according to claim 1.

3. The curved surface (C １ , C ２ The device (100) according to claim 2, wherein the surface is a concentric curved surface.

4. The curved surface (C １ , C ２ The device (100) according to any one of claims 1 to 3, wherein each of the ) is circular.

5. At least two elements have different longitudinal extensions (h １ , h ３ , H １ , H ２ , H ３ A device (100) according to any one of claims 1 to 4, having ).

6. The device (100) according to any one of claims 1 to 5, wherein the elements (1, 2) are separate elements (1, 2).

7. The device (100) according to claim 6, configured to allow adjustment of the position of the elements so as to form a passage that extends straight across the curved surface and in which no elements are positioned.

8. At least one of the first and second subsets (10, 20) is the same surface (C １ , C ２ A device (100) according to any one of claims 1 to 7, comprising two elements (1, 2) associated with ).

9. The first and second side ends (3, 4) of the elements (1, 2) are attached to the first and second supports (30a, 30b) spaced apart in the lateral direction, and the device allows the first and second supports (30a, 30b) to rotate independently about a common axis (A) extending in the lateral direction (LA), thereby enabling the closed surface (C １ , C ２ The device (100) according to any one of claims 1 to 8, configured to adjust the position of the elements (1, 2) along the )

10. Each of the first and second supports (30a, 30b) includes a plurality of first and second segments (31a, 31b, 32a, 32b), and the device (100) allows the first and second segments (31a, 31b, 32a, 32b) to rotate relative to each other, thereby enabling different curved surfaces (C １ , C ２ The device (100) according to claims 2 and 9, wherein the elements (1, 2) associated with the ) are configured to move relative to each other.

11. The device (100) according to any one of claims 1 to 10, further comprising means (40) for positioning the calibration device (100) between the X-ray source (210) and the X-ray detector (220) within the X-ray system (200).

12. The curved surface (C １ , C ２ The device (100) according to any one of claims 1 to 11, further comprising a stationary X-ray absorber disposed within ).

13. X-ray apparatus (1000) comprising: an X-ray system (200) having an X-ray source (210) that emits an X-ray beam (211) into a radiating surface; an X-ray detector (220) that receives the X-ray beam (211) and outputs a signal according to the amount of received radiation; and a calibration device (100) according to any one of claims 1 to 12, wherein the calibration device (100) is positioned between the X-ray source (210) and the X-ray detector (220) such that when the longitudinal directions of the elements (1, 2) of the first and second subsets (10, 20) are aligned in the alignment direction, the longitudinally extending portions of the elements (1, 2) of the first and second subsets (10, 20) are in the radiating surface along the radiation path (R) of the X-ray beam.

14. The X-ray apparatus (1000) according to claim 13, wherein the X-ray source (210) is configured to emit a fan-shaped X-ray beam (211) into a radiating surface, and the X-ray detector (220) includes a line detector positioned in the radiating surface to receive the radiation beam (211).

15. A method for calibrating the X-ray system of an X-ray apparatus (1000) according to claim 13 or 14, The steps include adjusting the position of the elements (1, 2) of the calibration device (100) to a first position such that the aligned longitudinal direction (LO) of the first subset (10) of the elements (1, 2) lies within the radiating plane, After adjusting the elements (1, 2) to the first position, the X-ray source (210) is operated to receive a first signal according to the first radiation dose that has passed through the elements (1, 2) of the first subset (10). The steps include adjusting the position of the elements (1, 2) of the calibration device (100) to a second position such that the aligned longitudinal direction (LO) of the second subset (20) of the elements (1, 2) lies within the radiating plane, After adjusting the elements (1, 2) to the second position, the X-ray source (210) is operated to receive a second signal according to the second radiation dose that has passed through the elements (1, 2) of the second subset (20). A step of calibrating the X-ray system (200) based on the first and second signals, Methods that include...

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