Multi-spectrum x-ray detector and automatic calibration method

Abstract

The application provides a multi-energy X-ray detector and an automatic calibration method, the multi-energy X-ray detector comprising: a lower cover, a support, a filter layer, a TFT module and an upper cover arranged in sequence above the lower cover; the filter layer is N in number, the TFT module is N+1 in number, and the filter layer and the TFT module are alternately stacked; wherein at least two markers are arranged between the outer surface of the lower cover and the upper surface of the bottommost TFT module, or at least two markers are arranged between the outer surface of the upper cover and the lower surface of the topmost TFT module; the material density of the markers is different from that of the adjacent material; N is an integer equal to or greater than 1. The multi-energy X-ray detector of the application does not need an additional jig for alignment and correction, reduces the system cost, and is simple and convenient to operate; can be applied to medical dual-energy radiography, and can also be applied to energy spectrum discrimination in other fields.

Description

Technical Field

[0001] This invention relates to the field of X-ray detection, and in particular to a multi-energy spectral X-ray detector and an automatic calibration method. Background Technology

[0002] Dual-energy subtraction angiography (DSA) in direct digital X-ray imaging can separate bone and soft tissue for independent visualization, reducing obstruction and improving the visibility of pulmonary nodular lesions. It can also differentiate between pulmonary and rib lesions in small chest nodules, leading to better characterization of these lesions. The absorption of X-rays by different tissues in the human body is related to the energy of the X-rays. In a dual-energy X-ray system, the different absorption rates of bone and soft tissues, and the differences in absorption effects between substances of different atomic weights, are more strongly reflected in the changes in the attenuation intensity of X-ray beams of different energies. Dual-energy subtraction angiography involves subtracting two images of the same body part obtained by exposing it with two different X-ray energies to obtain images of soft tissue, bone tissue, or specific substances.

[0003] Currently, there are two methods to achieve X-ray dual-energy silhouettes: the two-exposure method and the single-exposure method. The single-exposure method is typically implemented based on a dual-energy X-ray flat panel detector design, such as... Figure 1 As shown, the dual-energy spectral X-ray detector has a dual-layer X-ray sensor ( Figure 1 The X-ray system uses TFT modules 1 and 2. The upper sensor (TFT module 1) acquires low-energy images, while the X-rays, after passing through a filter layer, acquire high-energy images via the lower sensor (TFT module 2). Because both sensors image simultaneously, motion artifacts in the double-exposure method are eliminated, and the radiation dose to the patient and the requirements for the X-ray system are reduced. Figure 2 As shown, in actual X-ray imaging systems, the X-rays emitted from the X-ray source are not incident perpendicularly to the detector, and the distances from the X-ray source to the internal dual-layer sensors of the detector are different. Therefore, for dual-layer X-ray flat panel detectors, the images of the analyte left on the upper and lower sensor layers will have a magnification effect. Furthermore, for dual-layer X-ray flat panel detectors, during the structural assembly of the internal dual-layer sensors, pixel alignment accuracy issues are inevitable, and the alignment accuracy between the upper and lower layer pixels cannot be guaranteed through structural assembly alone. Therefore, when using the obtained upper and lower layer images for calculations, calculations cannot be performed directly based on the original pixel positions; it is necessary to find the correspondence between the upper and lower layer pixels.

[0004] Therefore, how to solve the problems of magnification effect and alignment accuracy between upper and lower layer images has become one of the urgent problems to be solved by those skilled in the art. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a multi-energy spectral X-ray detector and an automatic calibration method to solve the problems of amplification effect and low alignment accuracy of dual-layer X-ray flat panel detectors in the prior art.

[0006] To achieve the above and other related objectives, the present invention provides a multi-energy X-ray detector, comprising: a lower cover, a support member, a filter layer, a TFT module, and an upper cover sequentially disposed above the lower cover; the filter layer comprises N layers, the TFT module comprises N+1 layers, and the filter layer and the TFT module are alternately stacked;

[0007] Wherein, at least two markers are provided between the outer surface of the lower cover and the lower surface of the bottom TFT module, or at least two markers are provided between the outer surface of the upper cover and the upper surface of the top TFT module; the material density of the markers is different from that of the adjacent materials; N is an integer equal to or greater than 1.

[0008] Optionally, N is set to 1.

[0009] Optionally, the marker may be made of lead or tungsten.

[0010] Optionally, the marker may be cross-shaped or circular.

[0011] Optionally, the imaging area of ​​the marker does not intersect with the imaging area of ​​the object under test.

[0012] To achieve the above and other related objectives, the present invention also provides an automatic calibration method, the automatic calibration method comprising the following steps:

[0013] S1: Obtain the original images of the corresponding N+1 objects under test by N+1 TFT modules arranged sequentially along the X-ray incident direction;

[0014] S2: Calculate the edge contours of the markers in the N+1 original images using an edge detection operator;

[0015] S3: Calculate the size of the marker in each of the N+1 original images, and calculate the scaling ratio of the i-th original image relative to the first original image; where i is a consecutive integer greater than 1 and less than N+2;

[0016] S4: Based on the corresponding scaling ratio, perform global scaling on N original images respectively to obtain the corresponding scaled images;

[0017] S5: Obtain the first original image and N scaled images, mark the center points of two markers in each image, connect the two center points in the same image with a straight line, and calculate the angle formed by projecting the straight line in each scaled image onto the corresponding straight line in the first original image, and use the angle as the rotation angle.

[0018] S6: Using the center point of each rotation angle as the base point, rotate each scaled image to obtain the corresponding rotated image;

[0019] S7: Calculate the displacement between the center point of any one of the markers in each rotated image and the center point of the corresponding marker in the first original image;

[0020] S8: When detecting the object to be measured, firstly, the i-th image is globally scaled according to the corresponding scaling ratio, then the i-th image is rotated according to the corresponding rotation angle, and finally the i-th image is translated according to the corresponding displacement to obtain N automatically corrected images; the automatically corrected images are projected together with the first image and output.

[0021] Optionally, if the marker is between the outer surface of the lower cover and the lower surface of the bottommost TFT module, X-rays are incident from the lower cover side; if the marker is between the outer surface of the upper cover and the upper surface of the topmost TFT module, X-rays are incident from the upper cover side.

[0022] Optionally, step S5 may also be: acquiring a first original image and N scaled images, marking the center points of M markers in each image, connecting the center points of the M markers in the same image to each other with straight lines, and calculating the angle formed by projecting each straight line in each scaled image onto the corresponding straight line in the first original image, and using the average value of the angles as the rotation angle; where M is an integer greater than 2.

[0023] Optionally, steps S2 to S7 are performed on the image obtained by gain correction to obtain the scaling ratio, rotation angle, and displacement.

[0024] Optionally, in step S8, X-rays are used to detect the object to be tested from one side of the top cover.

[0025] As described above, the multi-energy spectral X-ray detector and automatic calibration method of the present invention have the following beneficial effects:

[0026] 1. The multi-energy spectral X-ray detector of the present invention does not require additional fixtures for alignment and calibration, which reduces system costs and is simple and convenient to operate.

[0027] 2. The multi-energy spectrum X-ray detector of the present invention does not require additional X-ray imaging. It only needs to obtain the correspondence between each image based on the original calibration to deduce the accurate image of the object under test.

[0028] 3. The multi-energy spectrum X-ray detector of the present invention can be applied to dual-energy silhouette in medicine, and can also be applied to energy spectrum resolution in other fields. Attached Figure Description

[0029] Figure 1 The diagram shows a structural schematic of a dual-energy X-ray detector in the prior art.

[0030] Figure 2 This diagram illustrates the amplification effect principle of a dual-energy X-ray detector in the prior art.

[0031] Figure 3 The diagram shown is a structural schematic of the multi-energy spectral X-ray detector of the present invention.

[0032] Figure 4 The diagram shows a schematic of the marker being placed on the top cover in the multi-energy spectral X-ray detector of the present invention.

[0033] Figure 5 This is a schematic diagram showing a low-energy image projected onto a high-energy image.

[0034] Figure 6 This is a schematic diagram showing a low-energy image projected onto a scaled image.

[0035] Figure 7 This is a schematic diagram showing the projection of a rotated image onto a low-energy image.

[0036] Figure 8 The image shown is a schematic diagram of the calibrated image.

[0037] Component designation explanation

[0038] 1. Bottom cover

[0039] 2 Support components

[0040] 3. Filter layer

[0041] 41 First TFT Module

[0042] 42 Second TFT Module

[0043] 5. Top Cover

[0044] 6. Markers

[0045] 7. Test Item

[0046] Steps S1 to S8 Detailed Implementation

[0047] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0048] Please see Figures 1 to 8 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0049] Example 1

[0050] like Figure 3 As shown, this embodiment provides a multi-energy X-ray detector, which includes at least: a lower cover 1, a support 2, a filter layer 3, a TFT module and an upper cover 5 sequentially disposed above the lower cover 1.

[0051] like Figure 3 As shown, the lower cover 1 and the upper cover 5 are used to protect the multi-energy X-ray detector.

[0052] like Figure 3 As shown, the support member 2 is disposed on the upper side of the lower cover 1 and is used to support the TFT module.

[0053] like Figure 3 As shown, there are N filter layers 3 and N+1 TFT modules. The filter layers 3 and the TFT modules are stacked alternately. The filter layers 3 are used to filter low-energy X-rays, and the TFT modules are used to acquire images of the object under test. N is an integer equal to or greater than 1.

[0054] As an example, N is set to 1, the filter layer 3 is a single layer, and there are two TFT modules: a first TFT module 41 and a second TFT module 42. The first TFT module 41 is disposed on the lower side of the filter layer 3, and the second TFT module 42 is disposed on the upper side of the filter layer 3. Through the filter layer 3, one TFT module can acquire low-energy images, and the other TFT module can acquire high-energy images. It should be noted that N can also take other values, and this example does not impose any restrictions.

[0055] like Figure 3As shown, at least two markers 6 are provided between the outer surface of the top cover 5 and the upper surface of the top TFT module.

[0056] Specifically, in this embodiment, at least two markers 6 are provided between the outer surface of the upper cover 5 and the upper surface of the second TFT module 42. Figure 3 The diagram shows two markers 6 on both the lower cover 1 and the upper cover 5. In this embodiment, the markers are located on one side of the upper cover 5 (this is for illustrative purposes only). The material density of the markers 6 is different from that of the adjacent materials, thus allowing a clear image to be left on each TFT module (the first TFT module 41 and the second TFT module 42). As an example, the material of the markers 6 is lead or tungsten. The markers 6 can also be other materials with a different material density than the adjacent materials, which is not limited here. The adjacent materials refer to the components in contact with the markers 6. In this embodiment, the markers 6 are located between the outer surface of the upper cover 5 and the upper surface of the second TFT module 42, and the material density of the markers 6 is different from that of the upper cover 5 and the second TFT module 42.

[0057] As an example, the number of markers 6 is 3 or 4, such as... Figure 4 As shown, the number of markers 6 in this embodiment is 4.

[0058] Specifically, the mark 6 is in the shape of a cross or a circle. The center point of the cross and the circle is easy to mark, which facilitates calibration. Making the mark 6 into other shapes is also applicable to this invention, and is not limited here.

[0059] Specifically, the imaging area of ​​the marker 6 does not intersect with the imaging area of ​​the object under test 7. In this embodiment, in order not to affect the imaging of the object under test 7, the four markers 6 are respectively set in the edge areas of the four corners of the upper cover 5; the markers 6 can also be set in other areas, not limited to this embodiment.

[0060] The multi-energy spectrum X-ray detector in this invention does not require a second or multiple X-ray imaging sessions. Multiple images of the object under test 7 can be obtained with a single X-ray imaging session, thereby obtaining the correspondence between the images.

[0061] Example 2

[0062] This embodiment provides an automatic calibration method based on the multi-energy spectral X-ray detector described in Embodiment 1. The automatic calibration method includes the following steps:

[0063] S1: Obtain the original images of the corresponding N+1 objects under test by using N+1 TFT modules arranged sequentially along the X-ray incident direction.

[0064] Specifically, such as Figure 3 As shown, the marker 6 is located between the outer surface of the upper cover 5 and the upper surface of the topmost TFT module (second TFT module 42). X-rays are incident from one side of the upper cover 5 (X-rays are incident from the side away from the lower cover 1). The first TFT module 41 acquires a high-energy image of the object under test 7, and the second TFT module 42 acquires a low-energy image of the object under test 7. It should be noted that the high-energy image and the low-energy image here are the unprocessed original images.

[0065] As an example, such as Figure 3 As shown, the object to be tested 7 is one, but it can be one or more, which is not limited here; in this embodiment, the object to be tested 7 is the letter "A", but it can also be other shapes and structures; the marker 6 is between the outer surface of the upper cover 5 and the upper surface of the second TFT module 42, and the object to be tested 7 is placed above the upper cover 5 for detection.

[0066] As an example, such as Figure 4 As shown, the markers 6 are located at the four corner edges of the upper cover 5 and are named: positioning marker 11, positioning marker 12, positioning marker 13, and positioning marker 14. Furthermore, the imaging area of ​​the markers 6 does not intersect with the imaging area of ​​the object under test 7. Figure 5 The diagram shows X-rays incident from one side of the upper cover 5, resulting in the second TFT module 42 acquiring a low-energy image of the test object 7, and the first TFT module 41 acquiring a high-energy image of the test object 7. The low-energy and high-energy images are projected together. The diagram shows that both the test object 7 and the marker 6 exhibit ghosting and magnification effects. It should be noted that in this embodiment, the marker 6 and the test object 7 are placed together for illustration, thus clearly showing the morphological changes of the test object 7, and the scaling, rotation, and translation between the high-energy and low-energy images of the test object 7.

[0067] S2: Calculate the edge contours of the marker 6 in the N+1 original images using the edge detection operator.

[0068] Specifically, as an example, the edge detection operators include, but are not limited to, the Sobel operator, the Prewitt operator, the Roberts operator, the Canny operator, or the Marr-Hildreth operator. These edge detection operators mark points in the image where brightness changes significantly, thereby identifying the complete image of the marker 6. It should be noted that the material density of the marker 6 differs from that of its adjacent materials, thus allowing the edge operators to mark points where brightness changes significantly.

[0069] As an example, the edge contour of the marker 6 in the two original images (the low-energy image and the high-energy image) is calculated using an edge detection operator.

[0070] S3: Calculate the size of the marker 6 in each of the N+1 original images, and calculate the scaling ratio of the i-th original image relative to the first original image; where i is a consecutive integer greater than 1 and less than N+2. It should be noted that when N is 1, i is 2.

[0071] Specifically, the size of the complete image of marker 6 in the low-energy image and the high-energy image are calculated respectively, and the scaling ratio of the high-energy image relative to the low-energy image (the first original image, the first image in the X-ray incident direction) is calculated.

[0072] S4: Based on the corresponding scaling ratio, perform global scaling on the N original images to obtain the corresponding scaled images. It should be noted that the N original images here are the N original images with a magnification effect, excluding the first image in the X-ray incident direction (the low-energy image).

[0073] Specifically, based on the magnification effect, the scaling ratio is greater than 1, and the high-energy image is globally reduced in size to obtain the scaled image. For example... Figure 6 The diagram shows a scaled image, after global downscaling of the high-energy image, projected onto the low-energy image.

[0074] S5: Obtain a first original image and N scaled images, mark the center points of at least two of the markers in each image, connect the center points of at least two of the markers in the same image with a straight line, and calculate the angle formed by projecting the straight line in each scaled image onto the corresponding straight line in the first original image, and use the angle as the rotation angle.

[0075] Specifically, such as Figure 6 As shown, scaled images of the low-energy image and the high-energy image are obtained. The center points of at least two markers 6 in both the low-energy image and the scaled image are marked. A straight line is drawn connecting the center points of the at least two markers 6 in the same image. The angle formed by projecting the straight line in the scaled image onto the corresponding straight line in the low-energy image is calculated and used as the rotation angle. It should be noted that when there are multiple TFT modules, along the X-ray direction, the X-rays pass through multiple filter layers 3, and the multiple TFT modules obtain multiple high-energy images, with the energy of the multiple high-energy images increasing sequentially.

[0076] As an example, when the number of markers 6 is two, such as Figure 6The positioning marks 11 and 14 in the image are connected to the center points of the two markers 6 in the low-energy image (positioning marks 11 and 14) to obtain a straight line; the center points of the two markers 6 in the scaled image (positioning marks 11' and 14') are connected to obtain another straight line; the included angle α formed by the two straight lines in the projection direction is calculated, and the included angle α is used as the rotation angle.

[0077] As another example, step S5 can also be: acquiring a first original image and N scaled images, marking the center points of M markers 6 in each image, connecting the center points of the M markers 6 in each image with straight lines, and calculating the angle formed by the projection of the straight lines in each scaled image onto the corresponding straight lines in the first original image, using the average value of the angles as the rotation angle; where M is an integer greater than 2. Specifically, this embodiment uses four markers 6, named as positioning marker 11, positioning marker 12, positioning marker 13, and positioning marker 14, respectively, and describes their placement on the four corner edges of the upper cover 5. Figure 6 As shown, the low-energy image and the scaled image are obtained, and the center points of the markers 6 in the low-energy image and the scaled image are marked respectively. The center points of the four markers 6 in the low-energy image and the scaled image are connected in pairs with straight lines (there are a total of 6 straight lines in each image). The angle formed by the projection of the straight line in the scaled image and the corresponding straight line in the low-energy image is calculated respectively. The average value of the angles is used as the rotation angle to reduce the error; where M is an integer greater than 2.

[0078] S6: Using the center point of each rotation angle as the base point, rotate each scaled image to obtain the corresponding rotated image.

[0079] Specifically, using the center point of the rotation angle α as the base point (the center point of the rotation angle α is the intersection point when the straight line in the scaled image and the corresponding straight line in the first original image are projected together), the scaled image is rotated (each image is a scaled image) so that the two sides of the rotation angle α coincide. For example... Figure 7 The diagram shows the scaled image after rotation and its projection onto the low-energy image.

[0080] S7: Calculate the displacement between the center point of any one of the markers 6 in each rotated image and the center point of the corresponding marker 6 in the first image.

[0081] Specifically, such as Figure 7As shown, select any center point of the marker 6 in the rotated image (such as positioning mark 11'), and calculate the horizontal and vertical displacements between this center point of the marker 6 and the corresponding center point of the marker 6 in the low-energy image (such as positioning mark 11). Figure 8 The diagram shows the result of horizontal and vertical translation, with the rotated image and the low-energy image projected together. This allows for a clear view of the sample 7. In the medical field, this method can eliminate artifacts and improve diagnostic efficiency. It can also be applied to other fields requiring energy spectrum resolution, which are not limited here.

[0082] As an example, the average displacement between the center points of any two or more of the markers 6 in each rotated image and the center point of the corresponding marker 6 in the first image is calculated to reduce the error.

[0083] S8: When detecting the object to be measured 7, firstly, the i-th image is globally scaled according to the corresponding scaling ratio, then the i-th image is rotated according to the corresponding rotation angle, and finally the i-th image is translated according to the corresponding displacement to obtain N automatically corrected images; the automatically corrected images are projected together with the first image and output.

[0084] Specifically, such as Figure 8 The diagram shows the high-energy image after global scaling, rotation, and translation, projected onto the low-energy image. The multi-energy spectral X-ray detector will... Figure 8 Output the results.

[0085] Specifically, in step S8, X-rays probe the object under test 7 from one side of the upper cover 5. After obtaining the scaling ratio, rotation angle, and translation relationship of the images between each TFT module, the image obtained by each TFT module 4 can be automatically calibrated directly, regardless of where the X-rays enter from.

[0086] As another implementation of this embodiment, the multi-energy X-ray detector undergoes gain correction before leaving the factory, and steps S2 to S7 are performed on the image obtained by gain correction to obtain the scaling ratio, rotation angle and displacement.

[0087] The multi-energy spectral X-ray detector of the present invention does not require additional fixtures for alignment and calibration, reducing system costs and making operation simple and convenient.

[0088] The multi-energy X-ray detector of the present invention has two TFT modules, or multiple modules. By setting the marker 6, the alignment and correction problem between different image sensors is solved.

[0089] Example 3

[0090] like Figure 3 As shown, this embodiment provides a multi-energy spectrum X-ray detector, which differs from the multi-energy spectrum X-ray detector described in Embodiment 1 in that: at least two markers 6 are provided between the outer surface of the lower cover 1 and the lower surface of the bottom TFT module 4. Figure 3 The diagram shows two markers 6 on both the lower cover 1 and the upper cover 5. In this embodiment, the markers are located on one side of the lower cover 1 (this is for illustrative purposes only).

[0091] Specifically, the marker 6 is disposed between the outer surface of the lower cover 1 and the lower surface of the first TFT module 41, and the material density of the marker 6 is different from that of the lower cover 1, the support member 2 and the first TFT module 41.

[0092] The other structures and principles of the multi-energy spectral X-ray detector in this embodiment are the same as those of the multi-energy spectral X-ray detector described in Embodiment 1, and will not be repeated here.

[0093] Example 4

[0094] This embodiment provides an automatic calibration method based on the multi-energy spectral X-ray detector described in Embodiment 3. The automatic calibration method differs from the automatic calibration method in Embodiment 2 in that: the marker 6 is located between the outer surface of the lower cover 1 and the lower surface of the bottommost TFT module (the first TFT module 41). X-rays are incident from one side of the lower cover 1 (X-rays are incident from the side away from the upper cover 5), thereby the second TFT module 42 acquires a high-energy image of the object under test 7, and the first TFT module 41 acquires a low-energy image of the object under test 7.

[0095] Specifically, the marker 6 is located between the outer surface of the lower cover 1 and the lower surface of the first TFT module 41, and the test object 7 is placed below the lower cover 1 for detection.

[0096] The other steps of the automatic calibration method in this embodiment are based on the same calibration principle as the automatic calibration method described in Embodiment 2, and will not be repeated here.

[0097] In summary, this invention provides a multi-energy spectral X-ray detector and an automatic calibration method. The multi-energy spectral X-ray detector includes: a lower cover, a support member, a filter layer, a TFT module, and an upper cover sequentially disposed above the lower cover; there are N filter layers and N+1 TFT modules, with the filter layers and TFT modules alternately stacked; wherein at least two markers are disposed between the outer surface of the lower cover and the upper surface of the bottommost TFT module, or at least two markers are disposed between the outer surface of the upper cover and the lower surface of the topmost TFT module; the material density of the markers is different from that of adjacent materials; N is an integer equal to or greater than 1. The multi-energy spectral X-ray detector of this invention does not require additional fixtures for alignment and calibration, reducing system costs and offering simple and convenient operation; it can be applied to dual-energy X-ray imaging in medicine and also to spectral resolution in other fields. Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability.

[0098] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. An automatic calibration method based on a multi-energy spectral X-ray detector, characterized in that, The multi-energy spectral X-ray detector includes at least a lower cover, a support member, a filter layer, a TFT module, and an upper cover sequentially disposed above the lower cover; there are N filter layers and N+1 TFT modules, with the filter layers and TFT modules alternately stacked; wherein at least two markers are disposed between the outer surface of the lower cover and the lower surface of the bottommost TFT module, or at least two markers are disposed between the outer surface of the upper cover and the upper surface of the topmost TFT module; the material density of the markers is different from that of adjacent materials; N is an integer equal to or greater than 1; the automatic calibration method includes the following steps: S1: Obtain N+1 original images of the object under test by N+1 TFT modules arranged sequentially along the X-ray incident direction; S2: Calculate the edge contours of the markers in the N+1 original images respectively using the edge detection operator; S3: Calculate the size of the marker in each of the N+1 original images, and calculate the scaling ratio of the i-th original image relative to the first original image; where i is a consecutive integer greater than 1 and less than N+2; S4: Based on the corresponding scaling ratio, perform global scaling on the 2nd to N+1th original images respectively to obtain the corresponding N scaled images; S5: Obtain the first original image and N scaled images, mark the center points of two markers in each image, connect the two center points in the same image with a straight line, and calculate the angle formed by projecting the straight line in each scaled image onto the corresponding straight line in the first original image, and use the angle as the rotation angle. S6: Using the center point of each rotation angle as the base point, rotate each scaled image to obtain the corresponding rotated image; S7: Calculate the displacement between the center point of any one of the markers in each rotated image and the center point of the corresponding marker in the first original image; S8: When detecting N+1 images of the object to be tested, firstly, the i-th image is globally scaled according to the corresponding scaling ratio, then the i-th image is rotated according to the corresponding rotation angle, and finally the i-th image is translated according to the corresponding displacement to obtain N automatically corrected images; the automatically corrected images are projected together with the first image and output.

2. The automatic calibration method according to claim 1, characterized in that: If the marker is located between the outer surface of the lower cover and the lower surface of the bottommost TFT module, X-rays will be incident from the lower cover side; if the marker is located between the outer surface of the upper cover and the upper surface of the topmost TFT module, X-rays will be incident from the upper cover side.

3. The automatic calibration method according to claim 1, characterized in that, Step S5 can also be: obtaining a first original image and N scaled images, marking the center points of M markers in each image, connecting the center points of the M markers in the same image to each other with straight lines, and calculating the angle formed by projecting each straight line in each scaled image onto the corresponding straight line in the first original image, and taking the average value of the angles as the rotation angle; where M is an integer greater than 2.

4. The automatic calibration method according to claim 1, characterized in that: Steps S2 to S7 are performed on the image obtained by gain correction to obtain the scaling ratio, rotation angle, and displacement.

5. The automatic calibration method according to claim 1, characterized in that: In step S8, X-rays are used to detect the object under test from one side of the top cover.

Images