Line artifact evaluation method, system, X-ray machine and storage medium

Abstract

Disclosed in embodiments of the present invention are a method, system, X-ray machine, and storage medium for evaluating line artifacts. The method includes: acquiring a captured image with and without a grid; performing a subtraction between the image with and without a grid to obtain a current line artifact image; determining the direction of line artifacts in the current line artifact image; calculating the pixel average value of each pixel row in the current line artifact image along the line artifact direction; calculating the pixel average value difference between adjacent pixel rows in the current line artifact image, and using the maximum pixel average value difference among all calculated pixel average value differences as the row pixel difference value of the current line artifact image, and recording the row pixel difference value; comparing the recorded row pixel difference value with a preset difference threshold value, and determining whether the line artifact is acceptable based on the comparison result. The technical solution in the embodiments of the present invention can achieve quantitative evaluation of line artifacts.

Description

Technical Field

[0001] The present invention relates to the medical field, and in particular to a line artifact evaluation method, system, X-ray machine and computer-readable storage medium. Background Art

[0002] In an X-ray machine, an X-ray source and an X-ray receiver (such as a flat-panel detector or an image detector) are mounted opposite each other so that the X-rays generated by the X-ray source penetrate an object and are incident on and detected by the X-ray receiver, thereby forming a projection image in digital radiographic imaging.

[0003] However, when X-rays penetrate an object, they are scattered. These scattered rays can reduce image contrast and signal-to-noise ratio, and thus affect image quality. To remove scattered rays, an anti-scatter grid is typically used between the X-ray source and the X-ray receiver. Existing anti-scatter grids are composed of alternating strips of low-absorption material (such as aluminum, carbon, or paper) and high-absorption material (such as lead). The grid transmits useful X-rays while blocking scattered rays. However, due to factors such as processing, the grid may form visible strip-shaped artifacts in the X-ray image, commonly referred to as line artifacts.

[0004] Minor line artifacts are generally acceptable because they do not affect clinical diagnosis. However, more pronounced line artifacts require appropriate artifact removal methods. Currently, determining whether line artifacts in an image are acceptable is typically done through visual inspection. However, this method is highly subjective and, for larger images containing gradual line artifacts, visual inspection often fails to reveal the severity of the artifact. Summary of the Invention

[0005] In view of this, the embodiments of the present invention propose, on the one hand, a method for evaluating line artifacts, and on the other hand, a system for evaluating line artifacts, an X-ray machine, and a computer-readable storage medium, so as to achieve quantitative evaluation of line artifacts to determine whether the line artifacts are acceptable.

[0006] A method for evaluating line artifacts provided in an embodiment of the present invention includes: acquiring a captured grid image and a non-grid image; performing a subtraction between the grid image and the non-grid image to obtain a current grid image; determining a direction of a line artifact in the current grid image; calculating a pixel average value for each pixel row in the current grid image along the line artifact direction; calculating pixel average value differences between adjacent pixel rows in the current grid image, taking a maximum pixel average value difference among all calculated pixel average value differences as a row pixel difference value of the current grid image, and recording the row pixel difference value; and comparing the recorded row pixel difference value with a preset difference threshold value, and determining whether the line artifact is acceptable based on the comparison result.

[0007] In one embodiment, before comparing the recorded row pixel differences with a preset difference threshold, the process further includes: determining whether a current downsampling count reaches a preset downsampling count threshold; if so, performing the operation of comparing all recorded row pixel differences with the preset difference threshold; otherwise, downsampling the current grid image to obtain a downsampled current grid image, incrementing the downsampling count by 1, and returning to perform the operation of calculating the pixel average value of each pixel row in the current grid image along the line artifact direction.

[0008] In one embodiment, after determining the direction of the line artifact in the current grid image and before calculating the pixel average value of each pixel row in the current grid image along the line artifact direction, the method further includes: rotating the current grid image according to a principle of making the line artifact direction parallel to horizontal rows or vertical columns, to obtain a rotated current grid image.

[0009] In one embodiment, determining the direction of the line artifact in the current grid image includes: performing Fourier transform on the current grid image to obtain a Fourier transform image; finding a position with a grayscale maximum value in an area other than a center point in the Fourier transform image; and determining the direction of the line artifact based on angle information of the position in the Fourier transform image.

[0010] In one embodiment, calculating the pixel average value difference between adjacent pixel rows in the current grid image includes: for each pixel row in the current grid image, calculating the pixel average value difference between the pixel row and an adjacent pixel row on a first side, or calculating the pixel average value difference between the pixel row and an adjacent pixel row on a second side, or calculating the pixel average value difference between the pixel row and adjacent pixel rows on both sides.

[0011] A line artifact assessment system provided in an embodiment of the present invention includes: a first unit for acquiring a captured grid image and a non-grid image; a second unit for performing a subtraction between the grid image and the non-grid image to obtain a current grid image; a third unit for determining a line artifact direction in the current grid image; a fourth unit for calculating a pixel average value for each pixel row in the current grid image along the line artifact direction; a fifth unit for calculating pixel average value differences between adjacent pixel rows in the current grid image, taking a maximum pixel average value difference among all calculated pixel average value differences as a row pixel difference value of the current grid image, and recording the row pixel difference value; and a sixth unit for comparing the row pixel difference value recorded by the fifth unit with a preset difference threshold value, and determining whether the line artifact is acceptable based on the comparison result.

[0012] In one embodiment, a seventh unit is further included between the fifth unit and the sixth unit, and the system further includes an eighth unit; the seventh unit is configured to determine whether a current downsampling count reaches a preset downsampling count threshold, and if so, trigger the sixth unit to perform an operation; otherwise, trigger the eighth unit to perform an operation; the eighth unit is configured to downsample the current grid image to obtain a downsampled current grid image, increment the downsampling count by 1, and trigger the fourth unit to perform an operation.

[0013] In one embodiment, between the third unit and the fourth unit, a ninth unit is further included, configured to rotate the current grid image according to the principle of making the direction of the line artifact parallel to the horizontal row or parallel to the vertical column, to obtain a rotated current grid image.

[0014] In one embodiment, the fifth unit calculates, for each pixel row in the current grid image, a pixel average difference between the pixel row and an adjacent pixel row on a first side, or a pixel average difference between the pixel row and an adjacent pixel row on a second side, or a pixel average difference between the pixel row and adjacent pixel rows on both sides.

[0015] In one embodiment, the third unit performs Fourier transform on the current grid image to obtain a Fourier transform image; finds a position with a grayscale maximum value in an area other than a center point in the Fourier transform image; and determines a direction of the line artifact based on angle information of the position in the Fourier transform image.

[0016] The line artifact assessment system proposed in an embodiment of the present invention is characterized by comprising: at least one memory and at least one processor, wherein: the at least one memory is used to store a computer program; and the at least one processor is used to call the computer program stored in the at least one memory to execute the line artifact assessment method described in any of the above embodiments.

[0017] An X-ray machine proposed in an embodiment of the present invention includes the line artifact evaluation system described in any one of the above embodiments.

[0018] The computer-readable storage medium proposed in the embodiment of the present invention stores a computer program thereon; the computer program can be executed by a processor and implement the line artifact evaluation method as described in any of the above embodiments.

[0019] As can be seen from the above scheme, in the embodiment of the present invention, a grid image is obtained by subtracting an image with a grid and an image without a grid, and the difference between adjacent pixel rows in the grid image along the direction of the line artifact is calculated. The difference between the adjacent pixel rows is compared with a set threshold to determine whether the line artifact is acceptable, thereby achieving quantitative evaluation of line artifacts and improving the intelligence, flexibility, and convenience of the X-ray system.

[0020] Furthermore, by downsampling the grid image a set number of times, calculating the difference between adjacent pixel rows based on the grid image after each downsampling, and comparing the difference between adjacent pixel rows of the undownsampled image and the image after each downsampling with the set threshold to determine whether the line artifact is acceptable, quantitative assessment of line artifacts in large-format images with gradient line artifacts that cannot be accurately assessed visually is achieved.

[0021] In addition, by rotating the grid image so that the direction of the line artifacts is parallel to the horizontal rows or parallel to the vertical columns, the calculation of the differences between adjacent pixel rows can be facilitated, thereby reducing the computational complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so that those skilled in the art will understand the above and other features and advantages of the present invention more clearly. In the accompanying drawings:

[0023] Figure 1 FIG. 4 is an exemplary flow chart of a method for evaluating line artifacts in an embodiment of the present invention.

[0024] Figure 2 FIG. 4 is an exemplary structural diagram of a line artifact evaluation system according to an embodiment of the present invention.

[0025] Figure 3FIG. 4 is an exemplary structural diagram of another line artifact evaluation system according to an embodiment of the present invention.

[0026] The accompanying drawings are numerals as follows:

[0027] Label meaning S11~S18 step 201 Unit 1 202 Unit 2 203 Unit 3 204 Unit 4 205 Unit 5 206 Unit 6 207 Unit 7 208 Unit 8 209 Unit 9 31 Memory 32 processor 33 monitor 34 bus DETAILED DESCRIPTION

[0028] In this embodiment of the present invention, considering that line artifacts are typically caused by non-uniformities in highly absorptive strip materials, the direction of the line artifacts aligns with the grid arrangement. Furthermore, the human eye is more sensitive to changes in adjacent areas. Therefore, the quantitative line artifact assessment scheme in this embodiment considers calculating the differences between adjacent pixel rows along the direction of the line artifact and comparing these differences with a set threshold to determine whether the line artifact is acceptable. Furthermore, to quantitatively assess line artifacts in larger images with gradient line artifacts, consideration is given to downsampling a set number of times. Based on each downsampled image, the differences between adjacent pixel rows are calculated. The differences between adjacent pixel rows in the undownsampled image and each downsampled image are then compared with the set threshold to determine whether the line artifact is acceptable.

[0029] In order to make the purpose, technical solution and effect of the present invention more clearly understood, the specific implementation methods of the present invention are now described with reference to the accompanying drawings.

[0030] In this document, "exemplary" and "illustrative" mean "serving as an example, instance, or illustration." Any diagram or implementation described in this document as "exemplary" or "illustrative" should not be interpreted as a more preferred or advantageous technical solution. To simplify the drawings, only the parts related to the present invention are schematically shown in each figure, and they do not represent the actual structure of the product. In this document, "one" not only means "only one", but also "more than one". In this document, "first", "second", etc. are only used to distinguish one from another, and do not indicate their importance or order.

[0031] Figure 1 FIG. 1 is an exemplary flow chart of a method for evaluating line artifacts according to an embodiment of the present invention. Figure 1 As shown, the method may include the following steps:

[0032] Step S11 : acquiring the collected grid image and non-grid image.

[0033] In this embodiment, the image captured when the grid is in place is referred to as the grid-mounted image Fw, and the image captured when the grid is not in place is referred to as the non-grid-mounted image Fo. In specific implementations, the images here can be aerial images without people or other scanned objects, although images with scanned objects are not limited thereto.

[0034] Step S12: Subtract the grid image from the non-grid image to obtain a current grid image.

[0035] In this embodiment, when the grid image and the non-grid image are subtracted, the non-grid image Fo can be subtracted from the grid image Fw, or the grid image can be subtracted from the non-grid image Fo. In specific implementation, the absolute value of the difference can be taken as needed.

[0036] Step S13: determining the direction of the line artifacts in the current grid image.

[0037] In this embodiment, if the grid line arrangement direction is known, the line artifact direction is directly determined to be the known grid line arrangement direction. If the grid line arrangement direction is unknown, various methods can be used in this step to detect the grid arrangement direction, i.e., the line artifact direction. For example, a Fourier transform image can be obtained by performing a Fourier transform on the current grid image. The location of the grayscale maximum in the region excluding the center point of the Fourier transform image is then located. The line artifact direction can then be determined based on the angle information of the location within the Fourier transform image.

[0038] Step S14 : calculating the pixel average value of each pixel row in the current grid image along the line artifact direction.

[0039] In this embodiment, if the line artifact direction is horizontal, the pixel average value of each pixel row in the current grid image is calculated along the horizontal direction; if the line artifact direction is vertical, the pixel average value of each pixel row in the current grid image (i.e., pixel rows arranged in the column direction) is calculated along the vertical direction; if the line artifact direction is an oblique direction other than the horizontal or vertical direction, the pixel average value of each pixel row in the current grid image (i.e., pixel rows arranged in the oblique direction) is calculated along the oblique direction. Of course, for the convenience of calculation, if the line artifact direction is an oblique direction other than the horizontal or vertical direction, in this embodiment, the current grid image can also be rotated according to the principle of making the line artifact direction parallel to the horizontal row or parallel to the vertical column, so that the line artifact direction is horizontal or vertical, thereby obtaining a rotated current grid image.

[0040] Step S15 , calculating pixel average differences between adjacent pixel rows in the current grid image, taking the maximum pixel average difference among all calculated pixel average differences as the row pixel difference of the current grid image, and recording the row pixel difference.

[0041] In this embodiment, for each pixel row in the current grid image, a pixel average difference between the pixel row and the adjacent pixel row on its first side may be calculated, such as E(i)-E(i-1); accordingly, the row pixel difference ΔE=max{E(i)-E(i-1)}. Alternatively, for each pixel row in the current grid image, a pixel average difference between the pixel row and the adjacent pixel row on its second side may be calculated, such as E(i)-E(i+1); accordingly, the row pixel difference ΔE=max{E(i)-E(i+1)}. Alternatively, for each pixel row in the current grid image, a pixel average difference between the pixel row and the adjacent pixel rows on both sides may be calculated, such as 2E(i)-E(i-1)-E(i+1); accordingly, the row pixel difference ΔE=max{2E(i)-E(i-1)-E(i+1)}. Where, E(i) is the average pixel value of the i-th pixel row, E(i-1) is the average pixel value of the i-1-th pixel row, and E(i+1) is the average pixel value of the i+1-th pixel row. i is a positive integer.

[0042] Step S16: comparing the recorded row pixel difference with a preset difference threshold, and determining whether the line artifact is acceptable based on the comparison result.

[0043] In this step, if the recorded row pixel difference is less than a preset difference threshold, it is determined that the line artifact is acceptable; otherwise, it is determined that the line artifact is unacceptable.

[0044] In addition, in other embodiments, step S17, as indicated by the dotted line, may be further included between step S15 and step S16 to determine whether the current number of downsampling times reaches a preset number threshold. If so, step S16 is executed; otherwise, step S18 is further executed to downsample the current grid image, for example, by a factor of 2, to obtain the downsampled current grid image, and the number of downsampling times is incremented by 1, and then the process returns to step S14. The initial value of the number of downsampling times is 0.

[0045] In this embodiment, if step S15 is recorded using a non-replacement method, then more than one row pixel difference value is typically recorded. In this case, in step S16, each row pixel difference value can be sequentially compared with a preset difference threshold. If all row pixel differences are less than the difference threshold, or a set number of row pixel differences are less than the difference threshold, then the line artifact can be determined to be acceptable; otherwise, the line artifact can be determined to be unacceptable. If step S15 is recorded using a replacement method, then the only row pixel differences recorded are those corresponding to the last downsampled grid image. In step S16, the row pixel differences corresponding to the last downsampled grid image can be directly compared with the preset difference threshold. If the difference is less than the difference threshold, then the line artifact can be determined to be acceptable; otherwise, the line artifact can be determined to be unacceptable.

[0046] Here, the preset downsampling times threshold can be set according to actual needs. For example, for thinner line artifacts, a lower downsampling times threshold can be set; for thicker line artifacts, a higher downsampling times threshold can be set.

[0047] The above describes in detail the line artifact assessment method according to the embodiment of the present invention. The following describes in detail the line artifact assessment system according to the embodiment of the present invention. The line artifact assessment system according to the embodiment of the present invention can be used to implement the line artifact assessment method according to the embodiment of the present invention. Details not disclosed in the embodiment of the system according to the present invention can be found in the corresponding description of the embodiment of the method according to the present invention and will not be detailed here.

[0048] Figure 2 FIG. 1 is an exemplary structural diagram of a system for evaluating line artifacts according to an embodiment of the present invention. Figure 2 As shown by the solid line portion in , the system may include: a first unit 201 , a second unit 202 , a third unit 203 , a fourth unit 204 , a fifth unit 205 and a sixth unit 206 .

[0049] The first unit 201 is used to obtain the collected grid image and non-grid image.

[0050] The second unit 202 is configured to perform a subtraction between the image with grid and the image without grid to obtain a current grid image.

[0051] The third unit 203 is configured to determine the direction of the line artifact in the current grid image. In a specific implementation, if the direction of the grid lines is known, the third unit 203 may directly determine the line artifact direction as the known direction of the grid lines. If the direction of the grid lines is unknown, the third unit 203 may perform a Fourier transform on the current grid image to obtain a Fourier transform image; locate the location of the grayscale maximum in the region of the Fourier transform image excluding the center point; and determine the direction of the line artifact based on the angle information of the location in the Fourier transform image.

[0052] The fourth unit 204 is configured to calculate a pixel average value of each pixel row in the current grid image along the line artifact direction.

[0053] The fifth unit 205 is configured to calculate pixel average differences between adjacent pixel rows in the current grid image, use the maximum pixel average difference among all calculated pixel average differences as the row pixel difference of the current grid image, and record the row pixel difference. Specifically, the fifth unit 205 may calculate, for each pixel row in the current grid image, the pixel average difference between the pixel row and the adjacent pixel rows on its first side, the pixel average difference between the pixel row and the adjacent pixel rows on its second side, or the pixel average difference between the pixel row and the adjacent pixel rows on both sides.

[0054] The sixth unit 206 is configured to compare the row pixel difference recorded by the fifth unit with a preset difference threshold, and determine whether the line artifact is acceptable based on the comparison result.

[0055] and Figure 1 In accordance with the method shown, in one embodiment, Figure 2 As shown by the dotted line portion in FIG, a seventh unit 207 is further included between the fifth unit 205 and the sixth unit 206 , and accordingly, the system further includes an eighth unit 208 .

[0056] The seventh unit 207 is used to determine whether the current downsampling times reaches a preset downsampling times threshold. If so, the sixth unit 206 is triggered to perform an operation; otherwise, the eighth unit 208 is triggered to perform an operation.

[0057] The eighth unit 208 is configured to downsample the current grid image to obtain a downsampled current grid image, increase the number of downsampling times by 1, and trigger the fourth unit 204 to perform an operation.

[0058] and Figure 1 In accordance with the method shown, in one embodiment, Figure 2As shown by the dotted line portion in FIG, between the third unit 203 and the fourth unit 204, the present invention further includes: a ninth unit 209, configured to rotate the current grid image according to the principle of making the direction of the line artifact parallel to the horizontal row or parallel to the vertical column, to obtain a rotated current grid image.

[0059] Figure 3 FIG. 1 is a structural diagram of another line artifact evaluation system according to an embodiment of the present invention. Figure 3 As shown, the system may include at least one memory 31 , at least one processor 32 and at least one display 33 . In addition, other components may be included, such as communication ports, etc. These components communicate via a bus 34 .

[0060] Among them, at least one memory 31 is used to store computer programs. In one embodiment, the computer program can be understood to include Figure 2 In addition, at least one memory 31 can also store an operating system, etc. Operating systems include but are not limited to: Android operating system, Symbian operating system, Windows operating system, Linux operating system, etc.

[0061] At least one display 33 is used to display images and human-computer interaction information.

[0062] At least one processor 32 is configured to invoke a computer program stored in at least one memory 31 to execute the line artifact assessment method described in the embodiments of the present invention. The processor 32 may be a CPU, a processing unit / module, an ASIC, a logic module, or a programmable gate array. The processor 32 may receive and transmit data via the communication port.

[0063] An embodiment of the present invention further provides an X-ray machine, which includes the line artifact evaluation system in any of the above embodiments.

[0064] It should be noted that not all steps and modules in the above processes and structure diagrams are required, and certain steps or modules can be omitted based on actual needs. The execution order of the steps is not fixed and can be adjusted as needed. The division of the modules is merely for the convenience of describing the functional division adopted. In actual implementation, a module can be implemented by multiple modules, and the functions of multiple modules can be implemented by the same module. These modules can be located in the same device or in different devices.

[0065] It is understood that the hardware modules in the above-mentioned embodiments can be implemented mechanically or electronically. For example, a hardware module may include a specially designed permanent circuit or logic device (such as a dedicated processor, such as an FPGA or ASIC) for performing a specific operation. The hardware module may also include a programmable logic device or circuit (such as a general-purpose processor or other programmable processor) temporarily configured by software to perform a specific operation. As for whether to implement the hardware module mechanically, or using a dedicated permanent circuit, or using a temporarily configured circuit (such as configured by software), it can be decided based on cost and time considerations.

[0066] In addition, embodiments of the present invention further provide a computer-readable storage medium having a computer program stored thereon. The computer program can be executed by a processor and implement the line artifact assessment method described in the embodiments of the present invention. Specifically, a system or device can be provided, equipped with a storage medium, on which software program code implementing the functions of any of the aforementioned embodiments is stored, and the computer (or CPU or MPU) of the system or device can read and execute the program code stored in the storage medium. Furthermore, instructions based on the program code can be used to cause an operating system, etc., operating on the computer to perform some or all of the actual operations. The program code read from the storage medium can also be written to a memory provided in an expansion board inserted into the computer or to a memory provided in an expansion unit connected to the computer. Subsequently, based on the instructions of the program code, a CPU, etc. installed in the expansion board or expansion unit can execute some or all of the actual operations, thereby implementing the functions of any of the aforementioned embodiments. Examples of storage media for providing the program code include floppy disks, hard disks, magneto-optical disks, optical disks (such as CD-ROMs, CD-Rs, CD-RWs, DVD-ROMs, DVD-RAMs, DVD-RWs, and DVD+RWs), magnetic tapes, non-volatile memory cards, and ROMs. Alternatively, the program code may be downloaded from a server computer via a communications network.

[0067] As can be seen from the above scheme, in the embodiment of the present invention, a grid image is obtained by subtracting an image with a grid and an image without a grid, and the difference between adjacent pixel rows in the grid image along the direction of the line artifact is calculated. The difference between the adjacent pixel rows is compared with a set threshold to determine whether the line artifact is acceptable, thereby achieving quantitative evaluation of line artifacts and improving the intelligence, flexibility, and convenience of the X-ray system.

[0068] Furthermore, by downsampling the grid image a set number of times, calculating the difference between adjacent pixel rows based on the grid image after each downsampling, and comparing the difference between adjacent pixel rows of the undownsampled image and the image after each downsampling with the set threshold to determine whether the line artifact is acceptable, quantitative assessment of line artifacts in large-format images with gradient line artifacts that cannot be accurately assessed visually is achieved.

[0069] In addition, by rotating the grid image so that the direction of the line artifacts is parallel to the horizontal rows or parallel to the vertical columns, the calculation of the differences between adjacent pixel rows can be facilitated, thereby reducing the computational complexity.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for evaluating line artifacts, characterized in that: include: Acquiring the collected grid image and non-grid image (S11); Subtracting the grid image from the non-grid image to obtain a current grid image (S12); determining a direction of a line artifact in the current grid image (S13); Calculating a pixel average value of each pixel row in the current grid image along the line artifact direction (S14); Calculating pixel average differences between adjacent pixel rows in the current grid image, taking the maximum pixel average difference among all the calculated pixel average differences as a row pixel difference of the current grid image, and recording the row pixel difference (S15); The recorded row pixel difference is compared with a preset difference threshold, and whether the line artifact is acceptable is determined based on the comparison result (S16).

2. The method for evaluating line artifacts according to claim 1, wherein: Before comparing the recorded row pixel difference with a preset difference threshold, the method further includes: It is determined whether the current number of downsampling times reaches a preset downsampling times threshold (S17). If so, the operation of comparing the recorded row pixel difference with a preset difference threshold is performed. Otherwise, the current grid image is downsampled to obtain a downsampled current grid image, the number of downsampling times is incremented by 1 (S18), and the process returns to the operation of calculating the pixel average value of each pixel row in the current grid image along the line artifact direction.

3. The method for evaluating line artifacts according to claim 1 or 2, wherein: After determining the direction of the line artifact in the current grid image (S13), and before calculating the pixel average value of each pixel row in the current grid image along the line artifact direction (S14), the method further includes: According to the principle of making the direction of the line artifact parallel to the horizontal row or parallel to the vertical column, the current grid image is rotated to obtain a rotated current grid image.

4. The method for evaluating line artifacts according to claim 1 or 2, wherein: The determining the direction of the line artifact in the current grid image (S13) includes: Performing Fourier transform on the current grid image to obtain a Fourier transform image; Find the position of the grayscale maximum value in the area other than the center point in the Fourier transform image; The direction of the line artifact is determined according to the angle information of the position in the Fourier transform image.

5. The method for evaluating line artifacts according to claim 1 or 2, characterized in that: The calculating the pixel average value difference between adjacent pixel rows in the current grid image (S14) includes: For each pixel row in the current grid image, a pixel average difference between the pixel row and an adjacent pixel row on a first side thereof is calculated, or a pixel average difference between the pixel row and an adjacent pixel row on a second side thereof is calculated, or a pixel average difference between the pixel row and adjacent pixel rows on both sides thereof is calculated.

6. A system for evaluating line artifacts, characterized in that include: The first unit (201) is used to obtain the collected grid image and non-grid image; The second unit (202) is configured to perform a subtraction between the image with grid and the image without grid to obtain a current grid image; A third unit (203) is configured to determine a direction of line artifacts in the current grid image; A fourth unit (204) is configured to calculate a pixel average value of each pixel row in the current grid image along the line artifact direction; a fifth unit (205) configured to calculate pixel average value differences between adjacent pixel rows in the current grid image, use the maximum pixel average value difference among all the calculated pixel average value differences as a row pixel difference value of the current grid image, and record the row pixel difference value; The sixth unit (206) is used to compare the row pixel difference recorded by the fifth unit with a preset difference threshold, and determine whether the line artifact is acceptable based on the comparison result.

7. The line artifact evaluation system according to claim 6, characterized in that: A seventh unit (207) is further included between the fifth unit (205) and the sixth unit (206), and the system further includes an eighth unit (208); The seventh unit (207) is used to determine whether the current downsampling times reaches a preset downsampling times threshold, and if so, trigger the sixth unit (206) to perform an operation; otherwise, trigger the eighth unit (208) to perform an operation; The eighth unit (208) is configured to downsample the current grid image to obtain a downsampled current grid image, increase the number of downsampling times by 1, and trigger the fourth unit (204) to perform an operation.

8. The line artifact evaluation system according to claim 6 or 7, characterized in that: Between the third unit (203) and the fourth unit (204), further comprising: The ninth unit (209) is configured to rotate the current grid image according to the principle of making the direction of the line artifact parallel to the horizontal row or parallel to the vertical column, to obtain a rotated current grid image.

9. The line artifact evaluation system according to claim 6 or 7, characterized in that: The fifth unit (205) calculates, for each pixel row in the current grid image, a pixel average difference between the pixel row and an adjacent pixel row on a first side thereof, or calculates a pixel average difference between the pixel row and an adjacent pixel row on a second side thereof, or calculates a pixel average difference between the pixel row and adjacent pixel rows on both sides thereof.

10. The line artifact evaluation system according to claim 6 or 7, characterized in that: The third unit (203) performs Fourier transform on the current grid image to obtain a Fourier transform image; finds the position of the grayscale maximum in the area other than the center point of the Fourier transform image; and determines the direction of the line artifact based on the angle information of the position in the Fourier transform image.

11. A system for evaluating line artifacts, characterized in that include: At least one memory (31) and at least one processor (32), wherein: The at least one memory (31) is used to store a computer program; The at least one processor (32) is configured to call a computer program stored in the at least one memory (31) to execute the line artifact evaluation method according to any one of claims 1 to 5.

12. An X-ray machine, characterized in that: A line artifact assessment system comprising the method according to any one of claims 6 to 11.

13. A computer-readable storage medium having a computer program stored thereon; characterized in that: The computer program can be executed by a processor and implements the line artifact evaluation method according to any one of claims 1 to 5 .

Images