X-ray focus measurement and analysis method, device and system

Abstract

The present invention relates to the field of X-ray focus measurement technology, and specifically discloses an X-ray focus measurement and analysis method, device, and system, including: obtaining a focus image formed by a photon detector, wherein the photon detector is capable of capturing X-rays emitted by an X-ray tube through a pinhole aperture and forming a focus image; performing image preprocessing on the focus image to obtain a preprocessed focus image; determining the actual focus position of the image in the preprocessed focus image; determining the target disk focus offset based on the actual focus position of the image and the imaging principle formed between the photon detector and the X-ray tube; performing focus stability analysis based on multiple target disk focus offsets formed by multiple focus images to obtain focus jitter quantitative analysis results. The X-ray focus measurement and analysis method provided by the present invention can detect the focus position offset while measuring the focus size of the X-ray tube irradiating the target disk.

Description

Technical Field

[0001] The present invention relates to the technical field of X-ray focus measurement, and in particular to an X-ray focus measurement and analysis method, an X-ray focus measurement and analysis device, and an X-ray focus measurement and analysis system. Background Art

[0002] The existing method for measuring the focal size of an X-ray tube on a target disk is to place a fixture on the tube's radiation exit surface. Inside the fixture is a diaphragm made of high-performance attenuating material, allowing the radiation to pass through the slit and reach the detector's receiving surface, thereby determining the radiation width on the detector plane. The actual focal size is then calculated based on the proportional relationship between the corresponding sides of similar triangles.

[0003] However, this measurement method in the existing technology cannot determine whether the focus position on the target disk is offset or whether the focus is jumping. Therefore, it cannot better verify the focus performance of the produced tube, and thus cannot guarantee the imaging quality of the tube, which will eventually lead to target surface damage and increased maintenance costs.

[0004] Therefore, how to measure the focal spot size of the X-ray tube on the target disk while detecting the offset of the focal spot position has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] The present invention provides an X-ray focus measurement and analysis method, an X-ray focus measurement and analysis device, and an X-ray focus measurement and analysis system, which solve the problem in the related art that only the size of the focus on the target disk can be measured but the offset of the focus position cannot be detected.

[0006] As a first aspect of the present invention, a method for measuring and analyzing an X-ray focus is provided, which includes: acquiring a focus image formed by a photon detector, wherein the photon detector is capable of capturing X-rays emitted by an X-ray tube through a pinhole aperture and forming a focus image; performing image preprocessing on the focus image to obtain a preprocessed focus image; determining an actual focus position of the image in the preprocessed focus image; determining a target disk focus offset based on the actual focus position of the image and an imaging principle formed between the photon detector and the X-ray tube; and performing focus stability analysis based on multiple target disk focus offsets formed by multiple focus images to obtain a focus jitter quantitative analysis result.

[0007] Furthermore, determining the actual focus position of the image in the preprocessed focus image includes: determining the focus geometric center of mass and the focus radius based on the spatial distribution of the connected domain in the preprocessed focus image and the grayscale characteristics; constructing a circle with the focus geometric center of mass as the center and the focus radius as the radius; and determining the actual focus position of the image based on all pixel points falling within the circle.

[0008] Furthermore, determining the focus geometric centroid according to the spatial distribution and grayscale features of the connected domain in the preprocessed focus image includes: performing grayscale weighted centroid calculation according to the grayscale values ​​of pixels in the connected domain in the preprocessed focus image to obtain centroid coordinates, wherein the calculation formula of the centroid coordinates is: ,in, Represents the pixel grayscale value; traverse all pixel points in the connected domain in the preprocessed focus image, and calculate the distance from each pixel point to the centroid coordinate to determine the focus radius.

[0009] Furthermore, the target focus offset is determined according to the actual focus position of the image and the imaging principle formed between the photon detector and the X-ray tube, including: determining the actual focus offset of the image according to the actual focus position of the image and the image center point position of the photon detector; determining the magnification ratio of the imaging model according to the distance between the photon detector and the X-ray tube; and determining the target focus offset according to the actual focus offset of the image and the magnification ratio of the imaging model.

[0010] Furthermore, the magnification ratio of the imaging model is determined according to the distance between the photon detector and the X-ray tube, including: determining the distance between two adjacent imaging foci on the photon detector according to the actual focus position of the image and the actual focus offset of the image; and determining the magnification ratio of the imaging model according to the distance between each two adjacent pinhole apertures, the distance between the pinhole aperture and the photon detector, and the distance between two adjacent imaging foci on the photon detector.

[0011] Furthermore, determining the target focus offset according to the actual focus offset of the image and the magnification ratio of the imaging model includes: determining that a ratio of the distance between the center point of the target and the pinhole aperture and the distance between the pinhole aperture and the focus of the photon detector is equal to a ratio between the target focus offset and the actual focus offset of the image; determining the ratio of the distance between the center point of the target and the pinhole aperture and the distance between the pinhole aperture and the focus of the photon detector as the magnification ratio of the imaging model; and determining the target focus offset according to the magnification ratio of the imaging model.

[0012] Furthermore, focus stability analysis is performed based on multiple target disk focus offsets formed by multiple focus images to obtain focus jitter quantitative analysis results, including: performing signal modeling on the multiple target disk focus offsets formed by the multiple focus images to obtain a time domain expression of the target disk focus offset; performing fast Fourier transform on the time domain expression of the target disk focus offset and then extracting the periodic jitter frequency component in the target disk focus offset; performing main jitter frequency and focus jitter frequency detection on the periodic jitter frequency component in the target disk focus offset to obtain focus jitter quantitative analysis results.

[0013] Furthermore, the focus image is subjected to image preprocessing to obtain a preprocessed focus image, including: performing image thresholding processing on the focus image to obtain a focus binary image; performing foreground area identification on the focus binary image and performing connected domain marking on the image after foreground area identification to obtain a preprocessed focus image.

[0014] As another aspect of the present invention, an X-ray focus measurement and analysis device is provided for implementing the X-ray focus measurement and analysis method described above, comprising: an image acquisition module for acquiring a focus image formed by a photon detector, wherein the photon detector is capable of capturing X-rays emitted by an X-ray tube through a pinhole aperture and forming a focus image; an image preprocessing module for performing image preprocessing on the focus image to obtain a preprocessed focus image; an image focus position determination module for determining the actual focus position of the image in the preprocessed focus image; a target focus offset determination module for determining a target focus offset based on the actual focus position of the image and the imaging principle formed between the photon detector and the X-ray tube; and a focus jitter analysis module for performing focus stability analysis based on multiple target focus offsets formed by multiple focus images to obtain a focus jitter quantitative analysis result.

[0015] As another aspect of the present invention, an X-ray focus measurement and analysis system is provided, comprising: a photon detector, an X-ray tube, a pinhole aperture, and a host computer, wherein the photon detector is communicatively connected to the host computer; an electron beam generated by an internal filament of the X-ray tube can be incident on an internal target disk and, after ionization, generates X-rays which are then irradiated on the photon detector through the pinhole aperture, and the photon detector can form a focus image based on the irradiation of the electron beam; the host computer includes the X-ray focus measurement and analysis device described above, and the X-ray focus measurement and analysis device in the host computer can obtain an actual focus offset of the image based on the focus image, determine a target disk focus offset based on the actual focus position of the image and an imaging principle formed between the photon detector and the X-ray tube, and perform focus stability analysis on multiple target disk focus offsets to obtain a quantitative analysis result of focus jitter.

[0016] The X-ray focus measurement and analysis method provided by the present invention obtains a focus image formed by a photon detector, preprocesses the focus image, and determines the image's actual focus position. Based on the image's actual focus position and the imaging principle formed between the photon detector and the X-ray tube, the target disk focus offset is determined. Finally, focus stability analysis is performed based on multiple target disk focus offsets formed from the multiple focus images. This X-ray focus measurement and analysis method can simultaneously measure the size of the focus irradiated by the X-ray tube on the target disk, detect the offset of the target disk focus position, and perform focus stability analysis, thereby effectively improving tube imaging quality and reducing abnormal target surface wear and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0018] Figure 1 This is a flow chart of the X-ray focus measurement and analysis method provided by the present invention.

[0019] Figure 2 This is a schematic diagram of the positions of the X-ray tube, photon detector, pinhole aperture and detector tooling provided by the present invention.

[0020] Figure 3 This is a flowchart of obtaining a pre-processed focus image provided by the present invention.

[0021] Figure 4a This is the focus image before image preprocessing provided by the present invention.

[0022] Figure 4b The focus binarized image obtained by the present invention.

[0023] Figure 4c This is the preprocessed focus image obtained after the image preprocessing provided by the present invention.

[0024] Figure 5 This is a flow chart for determining the actual focus position of an image provided by the present invention.

[0025] Figure 6 A flow chart for determining the target focus offset provided by the present invention.

[0026] Figure 7 Schematic diagram of the imaging model formed by the photon detector, pinhole aperture and X-ray tube provided by the present invention.

[0027] Figure 8 This is a schematic diagram of the ratio between the target focus offset and the actual image focus offset based on the pinhole aperture provided by the present invention.

[0028] Figure 9 This is a flow chart of obtaining focus jitter quantitative analysis results provided by the present invention.

[0029] Figure 10a This is a focus jitter quantitative analysis diagram in the X-axis direction provided by the present invention.

[0030] Figure 10b This is a focus jitter quantitative analysis diagram in the Y-axis direction provided by the present invention.

[0031] Figure 11a Another focus jitter quantitative analysis diagram in the X-axis direction provided by the present invention.

[0032] Figure 11b Another focus jitter quantitative analysis diagram in the Y-axis direction provided by the present invention.

[0033] Figure 12 This is a structural block diagram of the X-ray focus measurement and analysis device provided by the present invention. DETAILED DESCRIPTION

[0034] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first," "second," and the like in the specification and claims of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate for the embodiments of the present invention described herein. In addition, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to these processes, methods, products, or apparatuses.

[0037] In this embodiment, an X-ray focus measurement and analysis method is provided. Figure 1FIG. 1 is a flow chart of an X-ray focus measurement and analysis method according to an embodiment of the present invention. Figure 1 As shown, it includes: S100, obtaining a focus image formed by a photon detector, wherein the photon detector can capture the X-rays emitted by the X-ray tube through the pinhole aperture and form a focus image; in the embodiment of the present invention, specifically as follows Figure 2 Figure 1 shows the positions of the photon detector 1, pinhole aperture 2, and X-ray tube 3. When the X-ray tube 3 is operating, the target disk inside the tube rotates, and the filament generates an electron beam that strikes the target disk. Ionization generates X-rays, which then radiate out through the radiation window. These X-rays pass through the three apertures in the aperture and strike the photon detector, forming three focal images. The photon detector 1 is connected to the device housing the X-ray tube via a detector fixture 4.

[0038] S200. Perform image preprocessing on the focus image to obtain a preprocessed focus image. In an embodiment of the present invention, image preprocessing is performed on the focus image to achieve conversion from a grayscale image to a binary image, and dynamic threshold segmentation can be used to effectively distinguish between foreground areas with high grayscale values ​​(including focus features) and background areas with low grayscale values, thereby laying a foundation for subsequent feature extraction.

[0039] S300, determining the actual focus position of the image in the preprocessed focus image; in an embodiment of the present invention, the geometric centroid of the foreground area is calculated based on the preprocessed focus image to determine the actual focus position of the image.

[0040] S400. Determine a target disk focus offset based on the actual focus position of the image and an imaging principle formed between the photon detector and the X-ray tube. Specifically, determine the target disk focus offset based on the actual focus position of the image in combination with an imaging model formed by the photon detector and the X-ray tube.

[0041] It should be noted that, in the embodiment of the present invention, since the focus image formed by the photon detector is actually an image including three focuses, the focus offset can be obtained by combining the offset of the three focus images with the imaging principle in the actual imaging principle.

[0042] S500 , performing focus stability analysis based on multiple target disk focus offsets formed by multiple focus images to obtain a focus jitter quantitative analysis result.

[0043] By capturing multiple focus images at the same time, multiple target focus offsets can be obtained. Focus stability analysis of multiple target focus offsets can be performed to obtain the focus jitter amount, and finally the focus jitter quantitative analysis result can be obtained.

[0044] The X-ray focus measurement and analysis method provided by the present invention obtains a focus image formed by a photon detector, preprocesses the focus image, and determines the image's actual focus position. Based on the image's actual focus position and the imaging principle formed between the photon detector and the X-ray tube, the target disk focus offset is determined. Finally, focus stability analysis is performed based on multiple target disk focus offsets formed from the multiple focus images. This X-ray focus measurement and analysis method can simultaneously measure the size of the focus irradiated by the X-ray tube on the target disk, detect the offset of the target disk focus position, and perform focus stability analysis, thereby effectively improving tube imaging quality and reducing abnormal target surface wear and maintenance costs.

[0045] In an embodiment of the present invention, the focus image is preprocessed to obtain a preprocessed focus image, such as Figure 3 As shown, it includes: S210, performing image thresholding processing on the focus image to obtain a focus binary image; it should be understood that the embodiment of the present invention performs image thresholding processing on the focus image, which can realize the adaptive conversion of grayscale image to binary image, and effectively distinguishes the foreground area with high grayscale value (including focus features) from the background area with low grayscale value through dynamic threshold segmentation technology, thereby establishing a foundation for subsequent feature extraction.

[0046] Specifically, a dynamic threshold calculation mechanism is adopted. Its technical advantage lies in overcoming the environmental sensitivity of fixed thresholds. The specific process includes: a) extreme value detection: obtaining the maximum pixel intensity value (maxPixelValue ∈ [0,65535]) by scanning the entire image; b) adaptive threshold calculation: threshold = maxPixelValue × 5%, where 5% is an empirical coefficient derived from the statistical analysis of the distribution of microscopic image features to ensure that the top 5% of the highlighted effective areas are retained; c) binary mapping: Specifically, the maximum value of 16-bit unsigned integer is used to maintain data format consistency and generate a binary mask matrix.

[0047] like Figure 4a Shown is the focus image before image preprocessing. Figure 4b Shown is the obtained focus binarized image.

[0048] S220 , performing foreground region recognition on the focus binary image and performing connected component marking on the image after foreground region recognition to obtain a preprocessed focus image.

[0049] In the embodiment of the present invention, spatially discrete foreground regions in a binary image are accurately identified, and a regional topological structure is established by assigning unique labels, thereby laying a foundation for subsequent morphological analysis and feature measurement.

[0050] First, we implement the eight-connected domain labeling. Specifically, we use an iterative seed filling algorithm based on depth-first search (DFS), including: 1) neighborhood definition. Using the Moore neighborhood model, we define the eight-directional offsets as shown in Table 1.

[0051] Table 1 8-direction offset table

[0052]

[0053] 2) Stacked DFS process.

[0054] a) Initialization phase: Create a label matrix label_map, initialize it to 0, and set the current label counter label_num = 1.

[0055] b) Scan detection: traverse the image, and when it is detected that: I(x,y)==65535 and label_map(x,y)==0, create an empty stack and push (x,y) as the initial seed.

[0056] c) Area diffusion: while stack not empty: pop the top coordinate of the stack (current_x, current_y). If the coordinate is out of bounds or already marked, skip it and set label_map(current_x, current_y) = label_num.

[0057] The validity of the 8-neighborhood coordinates is checked: (1) within the image boundary (0 ≤ x < width, 0 ≤ y < height); (2) satisfying I(neighbor) == 65535; (3) unlabeled (label_map(neighbor) == 0); (4) the qualified neighborhood coordinates are pushed onto the stack.

[0058] d) Label update: When the stack is cleared, it means that the current connected domain is labeled, and label_num += 1 is executed.

[0059] like Figure 4c As shown, this is a picture after the connected domain is marked, which is also a preprocessed focus image obtained after image preprocessing.

[0060] In an embodiment of the present invention, the actual focus position of the image in the pre-processed focus image is determined, such as Figure 5 As shown, it includes: S310, determining the focus geometric centroid and focus radius according to the spatial distribution and grayscale characteristics of the connected domain in the preprocessed focus image.

[0061] In an embodiment of the present invention, based on the spatial distribution and grayscale characteristics of the connected domain, the geometric centroid of each foreground area is accurately calculated, and its spatial extension range is quantified, providing a geometric benchmark for accurate positioning and feature analysis of the focus area.

[0062] Specifically, the focus geometric centroid is determined according to the spatial distribution and grayscale features of the connected domain in the preprocessed focus image, including: (1) performing grayscale weighted centroid calculation according to the grayscale values ​​of pixels in the connected domain in the preprocessed focus image to obtain centroid coordinates, wherein the calculation formula of the centroid coordinates is: ,in, Represents the pixel grayscale value.

[0063] It should be understood that this embodiment of the present invention uses a grayscale weighted centroid method to improve the positioning accuracy of focused areas (high grayscale values) by weighting the spatial coordinates based on pixel grayscale values. The weighted centroid is more robust than the simple arithmetic mean centroid and is more affected by high grayscale areas (such as the focal point).

[0064] (2) Traversing all pixel points in the connected domain of the preprocessed focus image, and calculating the distance from each pixel point to the centroid coordinates to determine the focus radius.

[0065] Specifically, all pixels in the connected domain are traversed, the distance to the centroid is calculated, and the maximum value is taken as the region radius for subsequent ROI extraction.

[0066] S320: Construct a circle with the geometric centroid of the focus as the center and the focus radius as the radius.

[0067] Specifically, the focus centroid is used as the center of the circle and the radius is the circle, and the pixels within the circle are extracted as the central image for subsequent analysis.

[0068] S330: Determine the actual focus position of the image according to all pixel points falling within the circle.

[0069] Specifically, for each pixel (x, y), the focal centroid is calculated The square of the Euclidean distance: If the square of the distance is less than or equal to the square of the radius, the pixel is retained (set to 1, and retain the original value after multiplying with the original image), otherwise it is set to 0.

[0070] In the embodiment of the present invention, the target focus offset is determined according to the actual focus position of the image and the imaging principle formed between the photon detector and the X-ray tube, such as Figure 6 As shown, it includes: S410, determining the actual focus offset of the image according to the actual focus position of the image and the image center point position of the photon detector.

[0071] In the embodiment of the present invention, the position of the image center point of the photon detector is known, and the actual focus offset of the image can be determined according to the deviation between the actual focus position of the image and the image center point position of the photon detector.

[0072] It should be understood that the actual focus offset of the image is actually a pixel offset, and the physical unit offset can be obtained based on the coordinate system conversion. Therefore, the physical offset can be inferred from the focus position difference of multiple frames of image.

[0073] Specifically, the conversion of pixel units to physical units can be achieved through the following conversion formula: , among which Pixel Pitch Indicates the actual physical size of the pixel (such as micron level), Indicates the X coordinate offset in pixel offset, express The X offset in the corresponding physical quantity after conversion, Indicates the Y coordinate offset in pixel offset, express The Y offset of the corresponding physical quantity after conversion.

[0074] S420: Determine a magnification ratio of the imaging model according to the distance between the photon detector and the X-ray tube.

[0075] In an embodiment of the present invention, the target disk offset is inferred based on the trigonometric relationship. Specifically, the aperture-detector distance (Distance_Hole_Detector) and the pinhole position (Distance_Hole) can be used to calculate the magnification ratio of the actual imaging model.

[0076] Specifically, the magnification ratio of the imaging model is determined according to the distance between the photon detector and the X-ray tube, including: (1) determining the distance between two adjacent imaging foci on the photon detector according to the actual focal position of the image and the actual focal offset of the image.

[0077] It should be understood that there are three focal points on each focus image. According to the above description, the actual focus position and the actual focus offset of the image have been obtained. Therefore, the distance between the two adjacent imaging focal points on the photon detector can be obtained, that is, Figure 7 The distance x2 between two adjacent imaging foci of the photon detector 1 is shown.

[0078] (2) The magnification ratio of the imaging model is determined based on the distance between each two adjacent pinhole apertures, the distance between the pinhole aperture and the photon detector, and the distance between the two adjacent imaging foci on the photon detector.

[0079] It should be understood that since the distance x1 between each two adjacent pinhole apertures 2 is known, and the distance n between the pinhole aperture 2 and the photon detector 1 is known, the distance m from the X-ray tube 3 to the pinhole aperture 2 can be calculated according to the proportional relationship of similar triangles, that is, , from which the magnification ratio of the imaging model can be obtained as .

[0080] S430: Determine a target disk focus offset according to the actual focus offset of the image and the magnification ratio of the imaging model.

[0081] In an embodiment of the present invention, the target disk focus offset can be determined based on the magnification ratio of the imaging model obtained above.

[0082] Specifically, the target disk focus offset is determined according to the actual focus offset of the image and the magnification ratio of the imaging model, including: (1) according to the ratio of the distance between the center point of the target disk and the pinhole aperture and the distance between the pinhole aperture and the focus of the photon detector being equal to the ratio between the target disk focus offset and the actual focus offset of the image.

[0083] It should be understood that if Figure 8 As shown, the center point position of the target disk 31 in the X-ray tube 3 is known, the distance between the center point of the target disk 31 and the pinhole aperture 2 is m, and the distance between the pinhole aperture 2 and the central focus 11 in the focal image of the photon detector (since there are three focal points on the focal image, the focus at the central position is taken here) is n. Since the ratio of m to n has been obtained according to the above steps, and in the embodiment of the present invention, this ratio is also equal to the ratio between the target disk focus offset x3 and the actual image focus offset x4, that is, .

[0084] (2) The ratio of the distance between the center point of the target disk and the pinhole aperture and the distance between the pinhole aperture and the focus of the photon detector is determined as the magnification ratio of the imaging model.

[0085] In the embodiment of the present invention, it is determined .

[0086] (3) Determine the target focus offset according to the magnification ratio of the imaging model.

[0087] It should be understood that since the actual focus offset x4 of the image is known, it can be calculated based on The target focus offset can be obtained.

[0088] Specifically, the actual focus offset of the image is x4 ( , ), target focus offset x3 ( , ),therefore, , , and finally the target focus offset is obtained.

[0089] In an embodiment of the present invention, focus stability analysis is performed based on multiple target focus offsets formed by multiple focus images to obtain a focus jitter quantitative analysis result, such as Figure 9 As shown, it includes: S510, performing signal modeling on a plurality of target disk focus offsets formed by the plurality of focus images to obtain a time domain expression of the target disk focus offsets.

[0090] It should be understood that by converting the target disk focus offset into a time domain signal, frequency domain analysis can be achieved.

[0091] Specifically, the time domain sequence is constructed, and the X / Y direction offset sequence: the single frame offsets m_FocalX_Offset[i] and m_FocalY_Offset[i] are stored.

[0092] Sampling interval: ,in Indicates the sampling frequency; the actual frequency of the kth frequency point for: , N represents the total number of samples.

[0093] S520 , performing fast Fourier transform on the time domain expression of the target focus offset, and extracting the periodic jitter frequency component in the target focus offset.

[0094] Specifically, frequency analysis is achieved by extracting the periodic jitter component in the target focus offset.

[0095] The real and imaginary parts of the time domain sequence are obtained through fast Fourier transform (specifically, efficient FFT calculation can be performed by calling the cv::dft function in OpenCV), and then the spectrum amplitude is calculated.

[0096] The amplitude calculation formula is: The larger the amplitude, the higher the energy of the corresponding frequency component, indicating the presence of frequency jitter.

[0097] The normalized frequency resolution is: , where M represents the length of the time domain sequence.

[0098] S530 , performing main jitter frequency and focus jitter frequency detection on the periodic jitter frequency component in the target disk focus offset to obtain a focus jitter quantitative analysis result.

[0099] In an embodiment of the present invention, stability assessment of the periodic jitter frequency components in the target disk focus offset is primarily based on two core characteristic parameters: the main jitter frequency and the focus jitter frequency. The main jitter frequency is the global maximum jitter frequency found in the amplitude spectrum; the focus jitter frequency represents the frequency corresponding to a non-zero amplitude in the amplitude spectrum. The relationship between the number of frequency components present and stability is as follows: The greater the number of focus jitter frequency components N, the more complex the periodic jitter components contained in the focus offset signal. Jitter components of different frequencies may arise from the superposition of multiple physical factors (such as mechanical vibration and electromagnetic interference), resulting in unstable multi-periodic coupled motion of the focus position. For example, when N = 1, focus jitter is primarily dominated by a single frequency component, and the motion pattern is relatively predictable. When N = 3, jitter components of different frequencies modulate each other, potentially inducing complex nonlinear vibrations and exacerbating focus position fluctuations. The relationship between jitter amplitude and stability: The amplitude of each frequency component directly reflects the amplitude of the focus offset at the corresponding frequency. The larger the amplitude, the higher the peak value of the focus position offset within that frequency period. For example, if the amplitude of a frequency component is 0.5 μm, the maximum focus offset within that frequency period is 0.5 μm. If the amplitude of another component is 2 μm, its effect on the focus position is even more significant. Therefore, the presence of high-amplitude components in the amplitude spectrum directly reduces focus stability.

[0100] Figure 10a and Figure 10b This is a quantitative analysis chart of focus jitter from the X-axis and Y-axis directions, based on Figure 10a and Figure 10b As shown, each direction is divided into two figures, the upper figure is the actual focus jitter value, and the lower figure is the jitter frequency value. Figure 10a and Figure 10b The 200 focal points shown have jitter at very few points, so the FFT result curve is relatively flat without obvious peaks. Figure 11a and Figure 11b The following is a quantitative analysis of poor focus jitter characteristics. Figure 11a The focus shown has two jitter frequency components with the same amplitude, proving that the focus jitter is dominated by two frequency components and may be caused by two reasons (the reasons need to be analyzed according to the specific situation). Figure 11b The focus shown exhibits three jitter frequency components of varying amplitudes. These components can trigger a combined frequency response in nonlinear vibration, generating harmonic, sum, or difference frequency components, further exacerbating focus position instability. Prioritize analyzing the primary jitter frequency (with the largest amplitude) to prevent long-term coupling of these multiple frequency components and potential degradation of system accuracy.

[0101] In summary, the X-ray focus measurement and analysis device provided by the present invention obtains a focus image formed by a photon detector, preprocesses the focus image, and determines the image's actual focus position. The target disk focus offset is determined based on the image's actual focus position and the imaging principle formed between the photon detector and the X-ray tube. Finally, focus stability analysis is performed based on the multiple target disk focus offsets formed by the multiple focus images. This X-ray focus measurement and analysis method can simultaneously detect the offset of the target disk focus position while measuring the size of the focus irradiated by the X-ray tube on the target disk. It also performs focus stability analysis, thereby effectively improving tube imaging quality and reducing abnormal target surface wear and maintenance costs.

[0102] As another aspect of the present invention, an X-ray focus measurement and analysis device 100 is provided for implementing the above-mentioned X-ray focus measurement and analysis method, wherein Figure 12 As shown, it includes: an image acquisition module 110, used to acquire a focus image formed by a photon detector, wherein the photon detector is capable of capturing X-rays emitted by an X-ray tube through a pinhole aperture and forming a focus image; an image preprocessing module 120, used to perform image preprocessing on the focus image to obtain a preprocessed focus image; an image focus position determination module 130, used to determine the actual focus position of the image in the preprocessed focus image; a target focus offset determination module 140, used to determine the target focus offset according to the actual focus position of the image and the imaging principle formed between the photon detector and the X-ray tube; and a focus jitter analysis module 150, used to perform focus stability analysis based on multiple target focus offsets formed by multiple focus images to obtain a focus jitter quantitative analysis result.

[0103] The X-ray focus measurement and analysis device provided by the present invention obtains a focus image formed by a photon detector, pre-processes the focus image, and determines the image's actual focus position. Based on the image's actual focus position and the imaging principle formed between the photon detector and the X-ray tube, the target disk focus offset is determined. Finally, focus stability analysis is performed based on the multiple target disk focus offsets formed from the multiple focus images. This X-ray focus measurement and analysis device can simultaneously detect the offset of the target disk's focus position while measuring the size of the X-ray tube's focus on the target disk. It also performs focus stability analysis, effectively improving tube imaging quality and reducing abnormal target surface wear and maintenance costs.

[0104] The specific working principle of the X-ray focus measurement and analysis device provided by the present invention can be referred to the description of the X-ray focus measurement and analysis method above, and will not be repeated here.

[0105] As another embodiment of the present invention, an X-ray focus measurement and analysis system is provided, comprising: a photon detector, an X-ray tube, a pinhole aperture, and a host computer, wherein the photon detector is communicatively connected to the host computer; an electron beam generated by an internal filament of the X-ray tube can be incident on an internal target disk and, after refraction, passes through the pinhole aperture to illuminate the photon detector, and the photon detector can form a focus image based on the illumination of the electron beam; the host computer includes the X-ray focus measurement and analysis device described above, and the X-ray focus measurement and analysis device in the host computer can obtain an actual focus offset of the image based on the focus image, determine a target disk focus offset based on the actual focus position of the image and the imaging principle formed between the photon detector and the X-ray tube, and perform focus stability analysis on multiple target disk focus offsets to obtain a quantitative analysis result of focus jitter.

[0106] The X-ray focus measurement and analysis system provided by the present invention comprises a host computer including the aforementioned X-ray focus measurement and analysis device. The system obtains a focus image formed by a photon detector, pre-processes the focus image, and determines the image's actual focus position. The system then determines the target disk focus offset based on the image's actual focus position and the imaging principle formed between the photon detector and the X-ray tube. Finally, focus stability analysis is performed based on multiple target disk focus offsets formed from the multiple focus images. This X-ray focus measurement and analysis device can simultaneously detect the offset of the target disk's focus position while measuring the size of the X-ray tube's focus on the target disk. It also performs focus stability analysis, thereby effectively improving tube imaging quality and reducing abnormal target surface wear and maintenance costs.

[0107] The specific working principle of the X-ray focus measurement and analysis system provided by the present invention can be referred to the description of the X-ray focus measurement and analysis method above, and will not be repeated here.

[0108] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. An X-ray focus measurement and analysis method, characterized in that: include: Acquiring a focal image formed by a photon detector, wherein the photon detector is capable of capturing X-rays emitted by the X-ray tube through a pinhole aperture and forming a focal image; performing image preprocessing on the focus image to obtain a preprocessed focus image; determining an actual focus position of an image in the preprocessed focus image; Determining the target disk focus offset according to the actual focus position of the image and the imaging principle formed between the photon detector and the X-ray tube; Focus stability analysis is performed based on multiple target focus offsets formed by multiple focus images to obtain quantitative analysis results of focus jitter; Determining the target disk focus offset according to the actual focus position of the image and the imaging principle formed between the photon detector and the X-ray tube includes: Determining an actual focus offset of the image based on the actual focus position of the image and the image center point position of the photon detector; determining a magnification ratio of the imaging model according to the distance between the photon detector and the X-ray tube; Determining a target disk focus offset according to the actual focus offset of the image and the magnification ratio of the imaging model; Determining a magnification ratio of an imaging model according to a distance between the photon detector and the X-ray tube includes: Determine the distance between two adjacent imaging focal points on the photon detector according to the actual focal position of the image and the actual focal offset of the image; The magnification ratio of the imaging model is determined according to the distance between each two adjacent pinhole apertures, the distance between the pinhole aperture and the photon detector, and the distance between two adjacent imaging focal points on the photon detector; Determining the target disk focus offset according to the actual focus offset of the image and the magnification ratio of the imaging model includes: According to the ratio of the distance between the center point of the target disk and the pinhole aperture and the distance between the pinhole aperture and the focus of the photon detector being equal to the ratio between the focus offset of the target disk and the actual focus offset of the image; Determining the ratio of the distance between the center point of the target disk and the pinhole aperture and the distance between the pinhole aperture and the focus of the photon detector as the magnification ratio of the imaging model; Determining the target disk focus offset according to the magnification ratio of the imaging model; Focus stability analysis is performed based on multiple target focus offsets formed by multiple focus images to obtain quantitative analysis results of focus jitter, including: Performing signal modeling on a plurality of target focus offsets formed by the plurality of focus images to obtain a time domain expression of the target focus offsets; Performing a fast Fourier transform on the time domain expression of the target focus offset to extract a periodic jitter frequency component in the target focus offset; The main jitter frequency and focus jitter frequency of the periodic jitter frequency component in the target disk focus offset are detected to obtain a focus jitter quantitative analysis result.

2. The X-ray focus measurement and analysis method according to claim 1, characterized in that: Determining an actual focus position of the image in the preprocessed focus image includes: Determine the focus geometric centroid and focus radius according to the spatial distribution and grayscale characteristics of the connected domain in the preprocessed focus image; Construct a circle with the geometric centroid of the focus as the center and the focus radius as the radius; The actual focus position of the image is determined based on all pixel points falling within the circle.

3. The X-ray focus measurement and analysis method according to claim 2, characterized in that: Determining the focus geometric centroid according to the spatial distribution and grayscale features of the connected domain in the preprocessed focus image includes: Grayscale weighted centroid calculation is performed based on the grayscale values ​​of pixels in the connected domain in the preprocessed focus image to obtain centroid coordinates, wherein the calculation formula of the centroid coordinates is: ， Where I(x,y) represents the pixel grayscale value; All pixels in the connected domain of the preprocessed focus image are traversed, and the distance from each pixel to the centroid coordinates is calculated to determine the focus radius.

4. The X-ray focus measurement and analysis method according to claim 1, wherein: Performing image preprocessing on the focus image to obtain a preprocessed focus image includes: Performing image thresholding processing on the focus image to obtain a focus binary image; The foreground region of the focus binary image is identified and the connected domain of the image after the foreground region identification is marked to obtain a preprocessed focus image.

5. An X-ray focus measurement and analysis device, used to implement the X-ray focus measurement and analysis method according to any one of claims 1 to 4, characterized in that: include: An image acquisition module, configured to acquire a focal image formed by a photon detector, wherein the photon detector is capable of capturing X-rays emitted by the X-ray tube through a pinhole aperture and forming a focal image; An image preprocessing module, configured to perform image preprocessing on the focus image to obtain a preprocessed focus image; An image focus position determination module, configured to determine an actual focus position of the image in the preprocessed focus image; a target focus offset determination module, configured to determine the target focus offset according to the actual focus position of the image and the imaging principle formed between the photon detector and the X-ray tube; The focus jitter analysis module is used to perform focus stability analysis based on multiple target plate focus offsets formed by multiple focus images to obtain focus jitter quantitative analysis results.

6. An X-ray focus measurement and analysis system, characterized in that: include: A photon detector, an X-ray tube, a pinhole aperture and a host computer, wherein the photon detector is communicatively connected to the host computer; The electron beam generated by the internal filament of the X-ray tube can be projected onto the internal target disk and, after ionization, generate X-rays which are then irradiated onto the photon detector through the pinhole aperture. The photon detector can form a focal image according to the irradiation of the electron beam; The host computer includes the X-ray focus measurement and analysis device according to claim 5. The X-ray focus measurement and analysis device in the host computer can obtain the actual focus offset of the image based on the focus image, and determine the target disk focus offset based on the actual focus position of the image and the imaging principle formed between the photon detector and the X-ray tube, and can perform focus stability analysis on multiple target disk focus offsets to obtain focus jitter quantitative analysis results.

Images