A method for correcting bed settlement based on CT localization images and a computer-readable storage medium.

Abstract

This invention provides a method for correcting bed settlement based on CT positioning films, comprising: obtaining the standard boundary of the bed based on the positioning film scan; selecting two reference detector channels and obtaining the Y-axis height values ​​G1 and G2 of the two reference detector channels at the rotation center; obtaining a sequence H1 of the Y-axis height values ​​of the standard boundary at the rotation center based on the two reference detector channels; selecting a reconstruction center in the actual scan data and defining the distance between the reconstruction center and the rotation center as a compensation reference; substituting the compensation reference into the sequence H1 to obtain a compensation sequence B corresponding one-to-one with the values ​​in the sequence H1; and using the compensation sequence B to calibrate the actual scan data one-to-one. This invention calibrates the diagnostic bed at different vertical heights in the horizontal direction based on the results of the positioning film scan, and then compensates for the reconstruction at different horizontal positions to eliminate the influence of diagnostic bed settlement on the image.

Description

Technical Field

[0001] This invention relates to the field of CT image processing technology, and in particular to a method for correcting bed settlement based on CT positioning films and a computer-readable storage medium. Background Technology

[0002] Computed tomography (CT) is a device that uses rotating X-rays to illuminate a subject, then processes the image using a computer to obtain a cross-sectional image. Because basic CT images display transverse information, users sometimes use techniques such as MPR and VR to post-process a continuous horizontal segment of image to obtain more clinical information for clinical needs. The advent of wide-body detectors has accelerated axial scanning speeds, and the image quality of axial scanning is generally superior to helical scanning in transverse sections. Therefore, there is a demand for axial scanning for MPR and VR.

[0003] However, due to the inevitable horizontal movement of the diagnostic bed, some settling will occur. This settling will cause image misalignment, which may lead to errors in post-processing results and affect the visual appearance or diagnosis. During CT scans, the unavoidable settling of the diagnostic bed will cause vertical image deviation, affecting the performance of cross-slice images such as MPR.

[0004] Current technologies rely on mechanical design and material application to minimize diagnostic bed settlement, and generally discourage users from using techniques such as axial scanning for MPR and VR processing. However, due to the higher resolution of axial scanning, some users still have such needs. Although mechanical structure optimization and the use of more advanced materials can effectively reduce bed settlement, users' demands for the scanning length and maximum load capacity of diagnostic beds are also increasing, and these increases will inevitably lead to more significant bed settlement. Summary of the Invention

[0005] In order to overcome the above-mentioned technical defects, the purpose of this invention is to provide a method for correcting bed settlement based on CT positioning films and a computer-readable storage medium for correcting deviations in CT images caused by bed settlement.

[0006] This invention discloses a method for correcting bed settlement based on CT positioning films, comprising the following steps: obtaining the standard boundary of the bed board by scanning the positioning film, wherein the standard boundary is in the Z direction; selecting two reference detector channels and obtaining the Y-direction height values ​​G1 and G2 of the two reference detector channels at the rotation center; obtaining a sequence H1 of the Y-direction height values ​​of the standard boundary at the rotation center based on the two reference detector channels; selecting a reconstruction center in the actual scan data and defining the distance between the reconstruction center and the rotation center as the compensation reference; substituting the compensation reference into the sequence H1 to obtain a compensation sequence B that corresponds one-to-one with the values ​​in the sequence H1; and using the compensation sequence B to calibrate the actual scan data one-to-one to obtain calibrated scan data.

[0007] Preferably, obtaining the sequence H1 of Y-axis height values ​​of the standard boundary at the rotation center based on the two reference detector channels includes: obtaining sequences H1 and H2 of Y-axis height values ​​of the two standard boundaries at the rotation center based on the two reference detector channels; calculating the average value of sequences H1 and H2 in each Z-axis to obtain sequence I; and substituting the compensation reference into sequence H1 to obtain compensation sequence B corresponding to the values ​​in sequence H1 includes: substituting the compensation reference into sequence I to obtain compensation sequence B corresponding to the values ​​in sequence I.

[0008] Preferably, when the positioning piece is a side-mounted piece, the step of selecting two reference detector channels and obtaining the Y-axis height values ​​G1 and G2 of the two reference detector channels at the rotation center includes: selecting two reference detector channels, obtaining the detector positions D1 and D2 corresponding to the two reference detector channels; calculating the angles E1 and E2 between the two detector channels and the rotation center using the detector positions D1 and D2; and calculating the Y-axis height values ​​G1 and G2 of the two detector channels at the rotation center using the angles E1 and E2 and the distance F from the X-ray source focal point to the rotation center.

[0009] Preferably, when the positioning piece is a positive positioning piece, the step of selecting two reference detector channels and obtaining the Y-axis height values ​​G1 and G2 of the two reference detector channels at the rotation center includes: selecting two reference detector channels, obtaining the detector positions D1 and D2 corresponding to the two reference detector channels; calculating the angles E1 and E2 between the two detector channels and the rotation center using the detector positions D1 and D2; and calculating the Y-axis height values ​​G1 and G2 of the two detector channels at the rotation center using the angles E1 and E2, the distance F from the X-ray source focal point to the rotation center, the bed width K, and the distance J between the bed and the rotation center during scanning.

[0010] Preferably, the step of obtaining the standard boundaries on both sides of the bed board by scanning the positioning piece includes: when the positioning piece is a side positioning piece, the standard boundary is the lower boundary of the bed board; when the positioning piece is a front positioning piece, the standard boundary is the boundary of the left and right sides of the bed board.

[0011] Preferably, the step of obtaining the standard boundaries on both sides of the bed board by scanning the positioning plate includes: the Z-axis dimension of the standard boundary is greater than the safety threshold and less than the total length of the positioning plate; the safety threshold is calculated based on the maximum load and maximum travel of the bed board.

[0012] Preferably, obtaining the standard boundaries on both sides of the bed board by scanning the positioning plate includes: deleting abnormal points to obtain a smooth curve of the standard boundaries.

[0013] Preferably, the step of obtaining the standard boundaries on both sides of the bed board by scanning the positioning plate further includes: interpolating the missing points to obtain a smooth curve of the standard boundary.

[0014] Preferably, the step of selecting two reference detector channels and obtaining the detector positions D1 and D2 corresponding to the two reference detector channels further includes: if the reference detector channel corresponds to multiple pixels, then selecting a pixel close to the rotation center and obtaining the detector position corresponding to that pixel.

[0015] The present invention also discloses a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the bed board settlement correction method.

[0016] Compared with existing technologies, the above technical solution has the following advantages:

[0017] 1. This invention obtains the vertical height of the bed board at different positions in each horizontal direction based on the positioning film, and obtains the vertical height difference between each scan based on the horizontal position of each axial scan. This vertical height difference can be used to compensate for the height difference between each scan. The image can be corrected for the vertical height difference between each horizontal position in each scan for each patient, ensuring that the final transverse image is at the same vertical height, which is beneficial for subsequent image processing. No additional scanning is performed, no additional radiation is introduced, and it is suitable for anteroposterior, lateral, and dual-positioning films. Attached Figure Description

[0018] Figure 1 A flowchart of the bed slab settlement correction method based on CT positioning images provided by the present invention;

[0019] Figure 2 Another flowchart of the bed board settlement correction method based on CT positioning film provided by the present invention;

[0020] Figure 3 The diagram illustrates the calculation principle of the height values ​​G1 and G2 when the positioning piece provided by this invention is a side-positioning piece;

[0021] Figure 4 This is a schematic diagram illustrating the calculation principle of the height values ​​G1 and G2 when the positioning piece provided by this invention is a positive positioning piece. Detailed Implementation

[0022] The advantages of the present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments.

[0023] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0024] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0025] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0026] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0028] In the following description, suffixes such as "module," "part," or "unit" used to denote elements are used only for the convenience of the description of the invention and have no specific meaning in themselves. Therefore, "module" and "part" can be used interchangeably.

[0029] See appendix Figure 1-2 This invention discloses a method for correcting bed settlement based on CT positioning films. The method calibrates the vertical height of the diagnostic bed in the horizontal direction based on the scanning results of the positioning films, and then compensates for the reconstruction at different horizontal positions to eliminate the influence of diagnostic bed settlement on the image. The method includes the following steps:

[0030] S100. Obtain the standard boundary of the bed board by scanning the positioning plate. The standard boundary is in the Z direction.

[0031] S200. Select two reference detector channels and obtain the Y-axis height values ​​G1 and G2 of the two reference detector channels at the rotation center.

[0032] S300. Based on the two reference detector channels, obtain the sequence H1 of Y-axis height values ​​of the standard boundary at the rotation center;

[0033] S400. Select a reconstruction center in the actual scan data and define the distance between the reconstruction center and the rotation center as the compensation reference. Substitute the compensation reference into the sequence H1 to obtain the compensation sequence B that corresponds one-to-one with the values ​​in the sequence H1.

[0034] S500 uses the compensation sequence B to calibrate the actual scan data one by one, and obtains the calibrated scan data.

[0035] The purpose of step S100 is to obtain a boundary. Since the boundary between the bed board and the air is relatively easy to define, this boundary is usually the bed board boundary. Different positioning plates correspond to different boundaries, such as side positioning plates (see Appendix). Figure 3 This corresponds to the lower vertical boundary of the bed board, while the orthographic plate (see attached) Figure 4 The left and right edges of the bed board are the corresponding boundaries.

[0036] Specifically, the obtained boundary should be a one-pixel matrix in actual operation, for side-view images (see appendix). Figure 3This pixel matrix includes pixels in the X-direction and Z-direction, for positive-position patches (see Appendix). Figure 4 The pixel matrix includes pixels in the Y-direction and Z-direction.

[0037] When acquiring the boundary, what is actually acquired are the pixels. The distances between adjacent pixels are converted into straight lines using Hought calculation. Thus, connecting the straight lines between several pixels sequentially forms a boundary curve, which is referred to as the standard boundary in the preceding text. Of course, at the pixel size, the distances between adjacent pixels (the boundary) appear as straight lines, while at the positioning patch size, the boundary appears as a continuous, relatively smooth curve.

[0038] If any abnormal pixels are found during the inspection, causing obvious convex or concave points on the boundary curve, these abnormal pixels will be removed. This ensures a smoother boundary curve, facilitating subsequent processing.

[0039] Furthermore, after removing abnormal pixels, or if there are missing pixels during detection, the boundary curve will become noticeably skewed and therefore not smooth. Interpolation can be used to fill in the missing points and ensure the smoothness of the boundary curve.

[0040] Ideally, to ensure that the final boundary curve does not exhibit a large wavy shape, for side-view images, the deviation of the X pixels between the starting and ending points should be less than ±A. This A value is a preset adjustable value.

[0041] In boundary detection, some pixels may be faulty, rendering some data unusable. If the data volume is insufficient, the resulting boundary curve will be inaccurate. Therefore, to ensure the validity of the final boundary curve, the Z-axis length of the obtained boundary curve must be greater than a safety threshold during calculation to guarantee data sufficiency and thus accuracy.

[0042] In a preferred embodiment, the safety threshold is typically related to the settlement of the bed slab. Therefore, a rough estimate of the bed slab settlement can be obtained by calculating the load on the bed slab and the travel of the bed slab, and then a safety threshold can be estimated based on this settlement.

[0043] Since the boundary curve is obtained based on the positioning piece, if the Z-axis length of the boundary curve is greater than the total length of the positioning piece, the final boundary curve will be inaccurate. Therefore, it is also necessary to ensure that the Z-axis length of the obtained boundary curve is less than the total length of the positioning piece.

[0044] For step S300, preferably, in order to make the obtained compensation sequence B more accurate, the Y-axis height values ​​of the two standard boundaries at the rotation center can also be obtained simultaneously, and the average of them can be used to obtain a new sequence for subsequent compensation processing.

[0045] Specifically: Based on two reference detector channels, obtain the Y-axis height values ​​of the two standard boundaries at the rotation center, sequences H1 and H2; calculate the average value of sequences H1 and H2 in each Z-axis to obtain sequence I; substitute the compensation reference into sequence I to obtain the compensation sequence B, which corresponds one-to-one with the values ​​in sequence I.

[0046] For step S200, the calculation method for obtaining the Y-axis height value of the two detector channels at the rotation center varies depending on the type of positioning plate.

[0047] However, the similarity lies in the fact that although step S100 has obtained the position of the pixel in the X direction or the Y direction on the positioning piece, in order to ensure the accuracy of the final vertical height, it is necessary to convert all the points obtained in step S100 into height values ​​on the detector.

[0048] Next, when the positioning piece is a lateral positioning piece, see the appendix. Figure 3 Two reference detector channels are selected, and their corresponding detector positions D1 and D2 are obtained. Given the unit angle E corresponding to each pixel, the angles E1 and E2 between the two detector channels and the rotation center can be calculated using the detector positions D1 and D2. Finally, using the Pythagorean theorem, the Y-axis height values ​​G1 and G2 of the two detector channels at the rotation center are calculated using angles E1 and E2 and the distance F from the ray source focus to the rotation center: tanE1 = G1 / F; tanE2 = G2 / F.

[0049] When the positioning piece is in positive position, see the appendix. Figure 4 Similarly, two reference detector channels are selected, and the detector positions D1 and D2 corresponding to the two reference detector channels are obtained. Given the unit angle E corresponding to each pixel, the angles E1 and E2 between the two detector channels and the rotation center are calculated using the detector positions D1 and D2. Unlike side-view images, in the case of front-view images, it is also necessary to obtain the bed width K and the distance J between the bed and the rotation center during scanning. These, combined with the angles E1 and E2 and the distance F from the X-ray source focal point to the rotation center, are then used to calculate the Y-axis height values ​​G1 and G2 of the two detector channels at the rotation center.

[0050]

[0051] It should be noted that the G1 and G2 obtained here do not accurately represent the Y-axis height values ​​of the two detector channels at the center of rotation, but are only equivalent to the Y-axis height values ​​of the two detector channels at the center of rotation.

[0052] In the above steps of selecting two reference detector channels to obtain the detector positions D1 and D2 corresponding to the two reference detector channels, if the reference detector channel corresponds to multiple pixels, then select a pixel close to the rotation center to obtain the detector position corresponding to that pixel.

[0053] Preferably, for step S200, a photo of the bed board can be taken by a camera, and the vertical height of different positions in each horizontal direction can be obtained by analyzing the photo, or the vertical height of different positions in each horizontal direction can be obtained more accurately by a sensor (such as an infrared rangefinder).

[0054] In addition, for step S100, the boundary curve can also be obtained through AI algorithm.

[0055] This invention can correct the vertical height difference between each horizontal position in each scan for each patient, so that the final transverse image is at the same vertical height, which is beneficial for subsequent image processing.

[0056] The present invention also discloses a computer-readable storage medium storing a computer program thereon, wherein the steps of a bed settlement correction method are implemented when the computer program is executed by a processor.

[0057] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for correcting bed settlement based on CT positioning images, characterized in that, Includes the following steps: The standard boundary of the bed board is obtained by scanning the positioning plate, and the standard boundary is in the Z direction; Two reference detector channels are selected, and the Y-axis height values ​​G1 and G2 of the two reference detector channels at the rotation center are obtained; Based on the two reference detector channels, obtain the sequence H1 of Y-axis height values ​​of the standard boundary at the rotation center; In the actual scan data, a reconstruction center is selected, and the distance between the reconstruction center and the rotation center is defined as the compensation reference; the compensation reference is substituted into the sequence H1 to obtain the compensation sequence B that corresponds one-to-one with the values ​​in the sequence H1; The actual scan data are calibrated one by one using the compensation sequence B to obtain calibrated scan data; The sequence H1 for obtaining the Y-axis height value of the standard boundary at the rotation center based on the two reference detector channels includes: Based on the two reference detector channels, obtain the Y-axis height values ​​of the two standard boundaries at the rotation center, sequences H1 and H2; calculate the average value of sequences H1 and H2 in each Z-axis to obtain sequence I; The step of substituting the compensation benchmark into the sequence H1 to obtain the compensation sequence B that corresponds one-to-one with the values ​​in the sequence H1 includes: Substitute the compensation benchmark into the sequence I to obtain the compensation sequence B, which corresponds one-to-one with the values ​​in the sequence I; When the positioning piece is a side-mounted piece, selecting two reference detector channels and obtaining the Y-axis height values ​​G1 and G2 of the two reference detector channels at the rotation center includes: Two reference detector channels are selected, and the detector positions D1 and D2 corresponding to the two reference detector channels are obtained; the angles E1 and E2 between the two detector channels and the rotation center are calculated using the detector positions D1 and D2. The Y-axis height values ​​G1 and G2 of the two detector channels at the center of rotation are calculated using the angles E1 and E2 and the distance F from the focal point of the X-ray source to the center of rotation. When the positioning piece is a positive positioning piece, the step of selecting two reference detector channels and obtaining the Y-axis height values ​​G1 and G2 of the two reference detector channels at the rotation center includes: Two reference detector channels are selected, and the detector positions D1 and D2 corresponding to the two reference detector channels are obtained; the angles E1 and E2 between the two detector channels and the rotation center are calculated using the detector positions D1 and D2. The Y-axis height values ​​G1 and G2 of the two detector channels at the center of rotation are calculated using the angles E1 and E2, the distance F from the focal point of the X-ray source to the center of rotation, the width K of the bed board, and the distance J between the bed board and the center of rotation during scanning.

2. The method for correcting bed slab settlement according to claim 1, characterized in that, The step of obtaining the standard boundaries on both sides of the bed board by scanning the positioning plate includes: When the positioning piece is a side-positioning piece, the standard boundary is the lower boundary of the bed board; When the positioning piece is a positive positioning piece, the standard boundary is the boundary of the left and right sides of the bed board.

3. The method for correcting bed slab settlement according to claim 1, characterized in that, The step of obtaining the standard boundaries on both sides of the bed board by scanning the positioning plate includes: The Z-axis dimension of the standard boundary is greater than the safety threshold and less than the total length of the positioning piece; the safety threshold is calculated based on the maximum load and maximum stroke of the bed board.

4. The method for correcting bed slab settlement according to claim 1, characterized in that, The step of obtaining the standard boundaries on both sides of the bed board by scanning the positioning plate includes: Remove abnormal points to obtain a smooth curve of the standard boundary.

5. The method for correcting bed slab settlement according to claim 4, characterized in that, The step of obtaining the standard boundaries on both sides of the bed board by scanning the positioning plate also includes: Interpolation is performed on the missing points to obtain a smooth curve of the standard boundary.

6. The method for correcting bed slab settlement according to claim 1 or 2, characterized in that, The step of selecting two reference detector channels and obtaining the detector positions D1 and D2 corresponding to the two reference detector channels further includes: If the reference detector channel corresponds to multiple pixels, then select a pixel close to the rotation center and obtain the detector position corresponding to that pixel.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the bed slab settlement correction method according to any one of claims 1-6.

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