CT Scanning System Error Correction Method, Device, Equipment, and Storage Medium

Abstract

The CT scan system error correction method, device, equipment and medium provided by the embodiments of the present disclosure include: determining first attenuation data of a target phantom based on multi-energy X-rays at different rotation angles; determining the measured attenuation paths of X-rays passing through the target phantom at different rotation angles; determining second attenuation data of mono-energy X-rays passing through the target phantom at different rotation angles according to the measured attenuation paths and the conversion factor between the attenuation data and the attenuation paths under mono-energy X-rays; determining first target attenuation data and second target attenuation data under the target measured attenuation path according to the first attenuation data and the second attenuation data; and determining the mapping function between the mono-energy X-ray attenuation data and the multi-energy X-ray attenuation data under different target measured attenuation paths according to the first target attenuation data and the second target attenuation data under the target measured attenuation path. While beam hardening correction is achieved, detector response consistency correction is also achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of CT scanning and related technical fields. Specifically, it relates to a method, device, equipment, and storage medium for error correction of a CT scanning system. Background Art

[0002] CT scanning systems are widely used in the industrial and medical industries. In a CT scanning system, CT image reconstruction is based on the Lambert-Beer Law. In the formula, is the propagation path length, is the initial light intensity, is the light intensity after propagating length, is the attenuation coefficient. For monoenergetic X-rays, is a constant. For polyenergetic X-rays, since the proportion of low-energy photons gradually decreases during propagation (i.e., beam hardening), is no longer a constant. Therefore, in the scenario of polyenergetic X-rays, a CT scanning system needs to perform beam hardening correction. In addition, the detector module of a CT scanning system usually includes multiple channels. Different responses of different channels to X-rays with the same light intensity will cause artifacts in image reconstruction. Simple air correction can ensure the response consistency of different channels to X-rays without attenuation by the phantom. However, when polyenergetic X-rays pass through the phantom, their energy changes, and air correction cannot ensure the response consistency of different detection channels at this time. Nonlinear correction is required to ensure the response consistency of the detector to X-rays with different attenuations.

[0003] In the prior art, by scanning a water phantom placed off the rotation center, X-rays after passing through water with different thicknesses can be detected by all detection channels, and then this data is used for analysis such as hardening correction and nonlinear correction. During this process, in order to increase the statistics, operations such as increasing the current and multi-turn scanning are often required. Due to limitations such as the heat capacity of the lamp tube, such operations often greatly increase the data acquisition and analysis time. In addition, to obtain attenuation data of water equivalent to the size of an adult body part, a water phantom of an extremely large size often needs to be scanned, increasing the phantom cost and operation difficulty. Summary of the Invention

[0004] The embodiments described herein provide a method, device, equipment, and storage medium for error correction of a CT scanning system, which solve the problems existing in the prior art.

[0005] In a first aspect, according to the content of the present disclosure, a method for error correction of a CT scanning system is provided, including:

[0006] Determine the first attenuation data of the target phantom based on polyenergetic X-rays at different rotation angles, where the target phantom includes a first phantom and a second phantom, and the centers of the first phantom and the second phantom do not overlap with the rotation center;

[0007] Calculate the first attenuation path of the X-rays passing through the first phantom and the second attenuation path of the X-rays passing through the second phantom at different rotation angles, and determine the measured attenuation path of the X-rays passing through the target phantom at different rotation angles according to the first attenuation path and the second attenuation path;

[0008] Determine the second attenuation data of the monoenergetic X-rays passing through the target phantom at different rotation angles according to the measured attenuation path and the conversion factor between the attenuation data and the attenuation path under monoenergetic X-rays;

[0009] Determine the first target attenuation data and the second target attenuation data at the target measured attenuation path according to the first attenuation data and the second attenuation data;

[0010] Determine the mapping function between the monoenergetic X-ray attenuation data and the polyenergetic X-ray attenuation data at different target measured attenuation paths according to the first target attenuation data and the second target attenuation data at the target measured attenuation path.

[0011] In some embodiments of the present disclosure, the determining the first attenuation data of the target phantom based on polyenergetic X-rays at different rotation angles includes:

[0012] Obtain the initial attenuation data of the target phantom based on polyenergetic X-rays at different rotation angles, where the initial attenuation data includes detector channels and scanning angles;

[0013] Obtain the air attenuation data;

[0014] Correct the initial attenuation data based on the air attenuation data to obtain the first attenuation data.

[0015] In some embodiments of the present disclosure, the determining the measured attenuation path of the X-rays passing through the target phantom at different rotation angles according to the first attenuation path and the second attenuation path includes:

[0016] Sum the first attenuation path of the X-rays passing through the first phantom and the second attenuation path of the X-rays passing through the second phantom at the same rotation angle to obtain the initial measured attenuation path of the X-rays passing through the target phantom at different rotation angles;

[0017] Process the initial measured attenuation path according to the relationship between the first attenuation data and the preset attenuation data to obtain the measured attenuation path.

[0018] In some embodiments of the present disclosure, processing the initial measured attenuation path according to the relationship between the first attenuation data and the preset attenuation data to obtain a measured attenuation path includes:

[0019] When the pulse width of the first attenuation data is different from the pulse width of the preset attenuation data, determining the adjustment distances from the centers of the first phantom and the second phantom to the rotation center;

[0020] When the timing of the pulse peak of the first attenuation data is different from the timing of the pulse peak of the preset attenuation data, determining the adjustment deflection angles of the centers of the first phantom and the second phantom;

[0021] Adjusting the initial measured attenuation path according to the adjustment distances and adjustment deflection angles to obtain a measured attenuation path.

[0022] In some embodiments of the present disclosure, determining the first target attenuation data and the second target attenuation data under the target measured attenuation path according to the first attenuation data and the second attenuation data includes:

[0023] Obtaining a first correlation between the first attenuation data and the rotation angle, a second correlation between the second attenuation data and the rotation angle, and a third correlation between the measured attenuation path and the rotation angle;

[0024] According to the first correlation between the first attenuation data and the rotation angle, the second correlation between the second attenuation data and the rotation angle, the third correlation between the measured attenuation path and the rotation angle, the first attenuation data, and the second attenuation data, determining the first target attenuation data and the second target attenuation data under the target measured attenuation path.

[0025] In some embodiments of the present disclosure, before determining the mapping function between the monoenergetic X-ray attenuation data and the polyenergetic X-ray attenuation data under different target measured attenuation paths according to the first target attenuation data and the second target attenuation data under the target measured attenuation path, further includes:

[0026] Determining a first initial attenuation path according to the relationship between the first attenuation path and the first preset attenuation path, and determining a second initial attenuation path according to the relationship between the second attenuation path and the second preset attenuation path;

[0027] Determining a first initial rotation angle corresponding to the first initial attenuation path, and determining a second initial rotation angle corresponding to the second target attenuation;

[0028] Determining an initial rotation angle according to the first initial rotation angle and the second initial rotation angle;

[0029] Determine the measured attenuation paths of X-rays passing through the target phantom at different initial rotation angles according to the first initial attenuation path and the second initial attenuation path at different said initial rotation angles.

[0030] In some embodiments of the present disclosure, it further includes:

[0031] In response to receiving the multi-energy X-ray attenuation data of the test phantom at the test angle, determine the mono-energy X-ray attenuation data of the test phantom at the test angle according to the mapping function between the mono-energy X-ray attenuation data and the multi-energy X-ray attenuation data under the target measured attenuation path;

[0032] Perform back-projection reconstruction based on the mono-energy X-ray attenuation data of the test phantom at different test angles to obtain a scanned image.

[0033] In a second aspect, according to the content of the present disclosure, a CT scanning system error correction device is provided, including:

[0034] A first attenuation data determination module, configured to determine the first attenuation data of the target phantom based on multi-energy X-rays at different rotation angles, wherein the target phantom includes a first phantom and a second phantom, and the centers of the first phantom and the second phantom do not overlap with the rotation center;

[0035] A measured attenuation path determination module, configured to calculate the first attenuation path of X-rays passing through the first phantom and the second attenuation path of X-rays passing through the second phantom at different rotation angles, and determine the measured attenuation paths of X-rays passing through the target phantom at different rotation angles according to the first attenuation path and the second attenuation path;

[0036] A second attenuation data determination module, configured to determine the second attenuation data of mono-energy X-rays passing through the target phantom at different rotation angles according to the measured attenuation path and the conversion factor between the attenuation data and the attenuation path under mono-energy X-rays;

[0037] A target attenuation data association module, configured to determine a first target attenuation data and a second target attenuation data under the target measured attenuation path according to the first attenuation data and the second attenuation data;

[0038] A mapping function determination module, configured to determine the mapping function between the mono-energy X-ray attenuation data and the multi-energy X-ray attenuation data under different target measured attenuation paths according to the first target attenuation data and the second target attenuation data under the target measured attenuation path.

[0039] In a third aspect, according to the content of the present disclosure, a computer device is provided, including:

[0040] One or more processors;

[0041] A storage device for storing one or more programs

[0042] When the one or more programs are executed by the one or more processors, the one or more processors implement the method according to any one of the first aspect.

[0043] In a fourth aspect, according to the content of the present disclosure, there is provided a computer-readable storage medium having a computer program stored thereon, and when the program is executed by a processor, the method according to any one of the first aspect is implemented.

[0044] The CT scan system error correction method, device, equipment and medium provided by the embodiments of the present disclosure first determine the first attenuation data of a target phantom based on multi-energy X-rays at different rotation angles; and calculate the first attenuation path of X-rays passing through a first phantom and the second attenuation path of X-rays passing through a second phantom at different rotation angles, and determine the measured attenuation path of X-rays passing through the target phantom at different rotation angles according to the first attenuation path and the second attenuation path; then determine the second attenuation data of mono-energy X-rays passing through the target phantom at different rotation angles according to the measured attenuation path and the conversion factor between the attenuation data and the attenuation path under mono-energy X-rays; further determine the first target attenuation data and the second target attenuation data of mono-energy X-rays at the target measured attenuation path according to the first attenuation data and the second attenuation data; finally, determine the mapping function between the mono-energy X-ray attenuation data and the multi-energy X-ray attenuation data at different target measured attenuation paths according to the first target attenuation data and the second target attenuation data at the target measured attenuation path. It realizes the correction of multi-energy X-ray attenuation to mono-energy X-ray attenuation under the same path. While realizing beam hardening correction, since the same mono-energy attenuation coefficient is selected when establishing the mapping process of multi-energy X-rays to mono-energy X-rays for all detector channels, this mapping also realizes detector response consistency correction; in addition, the information of the tube energy spectrum and the filtration system is not applicable during the process of realizing beam hardening correction and detector response consistency correction. Therefore, when the tube energy spectrum or the filtration system changes significantly, such as the filtration deflects during installation, this correction algorithm is still effective.

[0045] The above description is only an overview of the technical solutions of the embodiments of the present application. In order to be able to understand the technical means of the embodiments of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the embodiments of the present application more obvious and understandable, the specific embodiments of the present application are specifically given below. Description of the Drawings

[0046] To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the accompanying drawings of the embodiments will be briefly described below. It should be understood that the following described drawings only relate to some embodiments of the present disclosure and do not limit the present disclosure, where:

[0047] Figure 1 is a schematic flowchart of a method for correcting CT scanning system errors provided by an embodiment of the present disclosure;

[0048] Figure 2 is a schematic structural diagram of a device for correcting CT scanning system errors provided by an embodiment of the present disclosure;

[0049] Figure 3 is a schematic structural diagram of a computer device provided by an embodiment of the present disclosure.

[0050] In the accompanying drawings, labels with the same last two digits correspond to the same elements. It should be noted that the elements in the drawings are schematic and not drawn to scale. Detailed Embodiments

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of the present disclosure without creative efforts also fall within the scope of protection of the present disclosure.

[0052] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the subject matter of the present disclosure belongs. Further, it will be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the specification and the relevant art, and will not be interpreted in an idealized or overly formal form unless otherwise clearly defined herein. As used herein, a statement that two or more parts are "connected" or "coupled" together shall mean that these parts are directly joined together or joined through one or more intermediate components.

[0053] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase "embodiments" appearing in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0054] As used herein, the term "and / or" is merely a description of the relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists, both A and B exist, and B exists. Additionally, in this text, the character " / " generally indicates an "or" relationship between the associated objects before and after.

[0055] In addition, in all embodiments of the present disclosure, terms such as "first" and "second" are only used to distinguish one component (or a part of the component) from another component (or another part of the component).

[0056] In the description of the present application, unless otherwise specified, the meaning of "a plurality" refers to two or more (including two). Similarly, "a plurality of groups" refers to two or more groups (including two groups).

[0057] To enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings.

[0058] Based on the problems existing in the prior art, the embodiments of the present disclosure provide a method for correcting the errors of a CT scanning system. Figure 1 It is a schematic flowchart of a method for correcting the errors of a CT scanning system provided by the embodiments of the present disclosure. As Figure 1 shown, the specific process of the method for correcting the errors of a CT scanning system includes:

[0059] S110. Determine the first attenuation data based on multi - energy X - rays of the target phantom at different rotation angles.

[0060] Among them, the target phantom includes a first phantom and a second phantom, and the centers of the first phantom and the second phantom do not overlap with the rotation center.

[0061] In a specific implementation manner, if it is desired to obtain large - path attenuation data, it is necessary to make the vertical projections of the first phantom and the second phantom on the scanning bed overlap as much as possible. At this time, the line connecting the center of the first phantom and the rotation center and the line connecting the center of the second phantom and the rotation center should be 0° or 180°; if it is desired to obtain small - path attenuation data, it is necessary to make the vertical projections of the first phantom and the second phantom on the scanning bed avoid overlapping as much as possible. At this time, the line connecting the center of the first phantom and the rotation center and the line connecting the center of the second phantom and the rotation center should be 90° or 270°, and the distances from the center of the first phantom to the rotation center and from the center of the second phantom to the rotation center should be as large as possible. Adjusting the placement positions of the first phantom and the second phantom can adjust the overlapping situation of their projections.

[0062] The embodiments of the present disclosure do not specifically limit the positions of the first phantom and the second phantom. If a mapping function between the large-path monoenergetic X-ray attenuation data and the multi-energy X-ray attenuation data is required, the line connecting the center of the first phantom and the rotation center and the line connecting the center of the second phantom and the rotation center are set to 0° or 180°. If a mapping function between the small-path monoenergetic X-ray attenuation data and the multi-energy X-ray attenuation data is required, the line connecting the center of the first phantom and the rotation center and the line connecting the center of the second phantom and the rotation center are set to 90° or 270°. The embodiments of the present disclosure do not specifically limit this.

[0063] In addition, the sizes of the first phantom and the second phantom need to be selected according to the object to be scanned during actual application and the geometric information of the CT. The embodiments of the present disclosure do not specifically limit this.

[0064] As a specific implementable manner, determining the first attenuation data of the target phantom based on multi-energy X-rays at different rotation angles includes: obtaining the initial attenuation data of the target phantom based on multi-energy X-rays at different rotation angles, where the initial attenuation data includes detector channels and scanning angles; obtaining air attenuation data; and correcting the initial attenuation data based on the air attenuation data to obtain the first attenuation data.

[0065] Specifically, the scanning device is rotated by controlling the current. Exemplarily, taking a current of 300 mA and sampling 1100 scanning angles per circle as an example, the target phantom is scanned. After scanning, the initial attenuation data of the target phantom based on multi-energy X-rays at different rotation angles is obtained , where i represents different scanning angles and j represents different detector channels. Then, the air is scanned under the same conditions to obtain the air attenuation data . Finally, the initial attenuation data is corrected based on the air attenuation data to obtain the first attenuation data, and the obtained first attenuation data satisfies: .

[0066] In addition, as a preferred implementation manner, the rotation device can be controlled to rotate multiple circles, and the attenuation data at the same scanning angle but different numbers of circles is averaged, which can reduce the error of the determined attenuation data.

[0067] By selecting first phantoms and second phantoms with appropriate sizes and combining the placement methods of the first phantoms and the second phantoms, large-path attenuation data or small-path attenuation data can be obtained, so the dependence on large-sized phantoms during the correction process can be reduced.

[0068] In addition, compared with the prior art that scans a single motif, the present application scans the first motif and the second motif, reducing the situation where only air attenuation data is detected by the channel at certain scanning angles. This situation not only causes waste of resources but also exposes the detector directly to the radiation of high-energy X-rays, increasing detector damage.

[0069] S120. Calculate the first attenuation path of the X-ray passing through the first motif and the second attenuation path of the X-ray passing through the second motif at different rotation angles, and determine the measured attenuation path of the X-ray passing through the target motif at different rotation angles according to the first attenuation path and the second attenuation path.

[0070] As a preferred implementable manner, determining the measured attenuation path of the X-ray passing through the target motif at different rotation angles according to the first attenuation path and the second attenuation path includes: summing the first attenuation path of the X-ray passing through the first motif and the second attenuation path of the X-ray passing through the second motif at the same rotation angle to obtain the initial measured attenuation path of the X-ray passing through the target motif at different rotation angles; processing the initial measured attenuation path according to the relationship between the first attenuation data and the preset attenuation data to obtain the measured attenuation path.

[0071] Specifically, processing the initial measured attenuation path according to the relationship between the first attenuation data and the preset attenuation data to obtain the measured attenuation path includes: when the pulse width of the first attenuation data is different from the pulse width of the preset attenuation data, determining the adjustment distances from the centers of the first motif and the second motif to the rotation center; when the timing of the pulse peak of the first attenuation data is different from the timing of the pulse peak of the preset attenuation data, determining the adjustment deflection angles of the centers of the first motif and the second motif; adjusting the initial measured attenuation path according to the adjustment distances and the adjustment deflection angles to obtain the measured attenuation path.

[0072] After placing the first motif and the second motif in the scanning device, the first attenuation path of the X-ray passing through the first motif and the second attenuation path of the X-ray passing through the second motif at different rotation angles can be measured according to the placement positions of the first motif and the second motif, and then the first attenuation path of the X-ray passing through the first motif and the second attenuation path of the X-ray passing through the second motif at the same rotation angle are summed to obtain the attenuation path of the X-ray of the target motif at this rotation angle. In this way, the attenuation paths of the X-ray of the target motif at different rotation angles are calculated in sequence, and then the initial measured attenuation path of the X-ray passing through the target motif is determined according to the attenuation paths of the X-ray passing through the target motif at different rotation angles.

[0073] As an example, if the X-axis coordinate and Y-axis coordinate of the center of the cross-section of the first motif satisfy:

[0074]

[0075]

[0076] The X-axis coordinate and Y-axis coordinate of the center of the cross-section of the second motif satisfy:

[0077]

[0078]

[0079] At this time, the first attenuation path of the X-ray passing through the first motif satisfies:

[0080]

[0081]

[0082] The second attenuation path of the X-ray passing through the second motif satisfies:

[0083]

[0084]

[0085] Among them, represents the X-axis coordinate of the center of the cross-section of the first motif, represents the Y-axis coordinate of the center of the cross-section of the first motif, represents the distance from the center of the first motif to the rotation center, is the cross-section radius of the first motif, is the deflection angle of the center of the first motif (with the eccentric angle when the motif is directly below the rotation center being 0° as the reference), represents the X-axis coordinate of the center of the cross-section of the second motif, represents the Y-axis coordinate of the center of the cross-section of the second motif, represents the distance from the center of the second motif to the rotation center, is the cross-section radius of the second motif, is the deflection angle of the center of the second motif (with the eccentric angle when the motif is directly below the rotation center being 0° as the reference), is the rotation angle of the radiation source, is the angle between the line connecting the radiation source to the detector channel and the line connecting the radiation source to the rotation center, is the distance from the radiation source to the rotation center.

[0086] After obtaining the first attenuation path of the first motif and the second attenuation path of the second motif at the rotation angle, the first attenuation path of the first motif and the second attenuation path of the second motif at the rotation angle are summed up to obtain at Measured attenuation path of the target phantom at the rotation angle.

[0087] During the actual operation process, the placement position of the target phantom often has a certain deviation from the preset position. Therefore, there is a certain difference between the initial measured attenuation path of the X-ray passing through the target phantom at different rotation angles calculated according to the above formula and the actual path. At this time, by fitting the first attenuation data and the preset attenuation data, according to the relationship between the pulse width of the first attenuation data after fitting and the pulse width of the preset attenuation data, and the relationship between the timing of the pulse peak of the first attenuation data and the timing of the pulse peak of the preset attenuation data, the positions of the first phantom and the second phantom are adjusted to change the deflection angle of the center of the first phantom and the distance from the center of the first phantom to the rotation center, and to change the deflection angle of the center of the second phantom and the distance from the center of the second phantom to the rotation center.

[0088] Specifically, when the pulse width of the first attenuation data is less than the pulse width of the preset attenuation data, the positions of the first phantom and the second phantom are adjusted respectively to increase the distance from the center of the first phantom to the rotation center and the distance from the center of the second phantom to the rotation center. When the pulse width of the first attenuation data is greater than the pulse width of the preset attenuation data, the positions of the first phantom and the second phantom are adjusted respectively to decrease the distance from the center of the first phantom to the rotation center and the distance from the center of the second phantom to the rotation center. When the timing of the pulse peak of the first attenuation data is earlier than the timing of the pulse peak of the preset attenuation data, the positions of the first phantom and the second phantom are adjusted respectively to increase the deflection angle of the center of the first phantom and the deflection angle of the center of the second phantom. When the timing of the pulse peak of the first attenuation data is later than the timing of the pulse peak of the preset attenuation data, the positions of the first phantom and the second phantom are adjusted respectively to decrease the deflection angle of the center of the first phantom and the deflection angle of the center of the second phantom.

[0089] In a specific embodiment, the adjustment distances from the centers of the first phantom and the second phantom to the rotation center can be determined according to the pulse widths of the first attenuation data and the preset attenuation data. The adjustment deflection angles of the centers of the first phantom and the second phantom can be determined according to the timings of the pulse peaks of the first attenuation data and the preset attenuation data. Then, the adjustment distance is summed with the distance from the center of the first phantom to the rotation center to obtain the target distance from the center of the first phantom to the rotation center. The adjustment distance is summed with the distance from the center of the second phantom to the rotation center to obtain the target distance from the center of the second phantom to the rotation center. The adjustment deflection angle is summed with the deflection angle of the center of the first phantom to obtain the target deflection angle of the center of the first phantom. The adjustment deflection angle is summed with the deflection angle of the center of the second phantom to obtain the target deflection angle of the center of the second phantom. Finally, the target distance from the center of the first phantom to the rotation center, the target distance from the center of the second phantom to the rotation center, the target deflection angle of the center of the first phantom, and the target deflection angle of the center of the second phantom are substituted into the above formula to obtain the measured attenuation path.

[0090] It should be noted that the preset attenuation data is the attenuation data generated by the target phantom at different rotation angles at a preset position based on monoenergetic X-rays.

[0091] S130. Determine the second attenuation data of the monoenergetic X-ray passing through the target phantom at different rotation angles according to the measured attenuation path and the conversion factor between the attenuation data and the attenuation path under monoenergetic X-rays.

[0092] Regardless of whether the target phantom is under monoenergetic X-rays or polyenergetic X-rays, when the rotation angle is the same, the attenuation path is fixed. The conversion factor between the attenuation data and the attenuation path under monoenergetic X-rays is a fixed value, and the attenuation data of the monoenergetic X-ray passing through the target phantom and the attenuation path satisfy: . Therefore, when the measured attenuation path of the target phantom at different rotation angles is known and the conversion factor between the attenuation data and the attenuation path under monoenergetic X-rays is known, the second attenuation data of the monoenergetic X-ray passing through the target phantom at different rotation angles can be obtained.

[0093] S140. Determine the first target attenuation data and the second target attenuation data under the target measured attenuation path according to the first attenuation data and the second attenuation data.

[0094] In a specific embodiment, determining the first target attenuation data and the second target attenuation data under the target measurement attenuation path according to the first attenuation data and the second attenuation data includes: obtaining a first correlation relationship between the first attenuation data and the rotation angle, a second correlation relationship between the second attenuation data and the rotation angle, and a third correlation relationship between the measurement attenuation path and the rotation angle; determining the first target attenuation data and the second target attenuation data under the target measurement attenuation path according to the first correlation relationship between the first attenuation data and the rotation angle, the second correlation relationship between the second attenuation data and the rotation angle, the third correlation relationship between the measurement attenuation path and the rotation angle, the first attenuation data, and the second attenuation data.

[0095] Specifically, according to step S110, the first attenuation data at different rotation angles can be obtained. Therefore, according to the first attenuation data at different rotation angles, the first correlation relationship between the first attenuation data and the rotation angle can be obtained. According to step S120, the measurement attenuation paths of the target phantom at different rotation angles can be obtained. Therefore, according to the measurement attenuation paths of the target phantom at different rotation angles, the third correlation relationship between the measurement attenuation path and the rotation angle can be obtained. According to step S130, the second attenuation data at different rotation angles can be obtained. Therefore, according to the second attenuation data at different rotation angles, the second correlation relationship between the second attenuation data and the rotation angle can be obtained.

[0096] After obtaining the first correlation relationship between the first attenuation data and the rotation angle, the second correlation relationship between the second attenuation data and the rotation angle, and the third correlation relationship between the measurement attenuation path and the rotation angle, if a rotation angle of the scanning device is selected, the measurement attenuation path at this rotation angle can be determined according to the third correlation relationship between the measurement attenuation path and the rotation angle. Then, the first attenuation data at this rotation angle can be determined according to the first correlation relationship between the first attenuation data and the rotation angle, and the second attenuation data at this rotation angle can be determined according to the second correlation relationship between the second attenuation data and the rotation angle. Finally, the first attenuation data and the second attenuation data under this measurement attenuation path are obtained, that is, the first target attenuation data and the second target attenuation data under the target measurement attenuation path.

[0097] S150. Determine the mapping function between the monoenergetic X-ray attenuation data and the polyenergetic X-ray attenuation data under different target measurement attenuation paths according to the first target attenuation data and the second target attenuation data under the target measurement attenuation path.

[0098] After step S140 determines the first target attenuation data and the second target attenuation data under the target measurement attenuation path, a mapping function between the monoenergetic X-ray attenuation data and the polyenergetic X-ray attenuation data under different target measurement attenuation paths is constructed according to the first target attenuation data and the second target attenuation data.

[0099] After constructing the mapping function between the mono - energy X - ray attenuation data and the multi - energy X - ray attenuation data under different target measurement attenuation paths, during the actual scanning process, when the scanning device rotates to a test angle, the measurement attenuation path of the measurement phantom at this test angle can be obtained. Then, find the mapping function between the mono - energy X - ray attenuation data and the multi - energy X - ray attenuation data corresponding to this measurement attenuation path. Furthermore, according to the mapping function between the mono - energy X - ray attenuation data and the multi - energy X - ray attenuation data corresponding to this measurement attenuation path, convert the collected multi - energy X - ray attenuation data into mono - energy X - ray attenuation data, and then image reconstruction can be performed according to the Lambert - Beer law.

[0100] The CT scan system error correction method provided by the embodiments of the present disclosure first determines the first attenuation data of the target phantom based on multi - energy X - rays at different rotation angles; and calculates the first attenuation path of the X - rays passing through the first phantom and the second attenuation path of the X - rays passing through the second phantom at different rotation angles, and determines the measurement attenuation path of the X - rays passing through the target phantom at different rotation angles according to the first attenuation path and the second attenuation path; then determines the second attenuation data of the mono - energy X - rays passing through the target phantom at different rotation angles according to the measurement attenuation path and the conversion factor between the attenuation data and the attenuation path under mono - energy X - rays; furthermore, determines the first target attenuation data and the second target attenuation data under the target measurement attenuation path according to the first attenuation data and the second attenuation data; finally, determines the mapping function between the mono - energy X - ray attenuation data and the multi - energy X - ray attenuation data under different target measurement attenuation paths according to the first target attenuation data and the second target attenuation data under the target measurement attenuation path. It realizes the correction of multi - energy X - ray attenuation to mono - energy X - ray attenuation under the same path. While realizing beam hardening correction, since the same mono - energy attenuation coefficient is selected when establishing the mapping process from multi - energy X - rays to mono - energy X - rays for all detector channels, this mapping also realizes the detector response consistency correction; in addition, during the process of realizing beam hardening correction and detector response consistency correction, the information of the tube energy spectrum and the filtration system is not applicable. Therefore, when there are significant changes in the tube energy spectrum or the filtration system, such as the filtration deflects during installation, this correction algorithm is still effective.

[0101] Based on the above - mentioned embodiments, before performing step S150, it further includes:

[0102] According to the relationship between the first attenuation path and the first preset attenuation path, the first initial attenuation path is determined, and according to the relationship between the second attenuation path and the second preset attenuation path, the second initial attenuation path is determined; the first initial rotation angle corresponding to the first initial attenuation path is determined, and the second initial rotation angle corresponding to the second target attenuation is determined; the initial rotation angle is determined according to the first initial rotation angle and the second initial rotation angle; according to the first initial attenuation path and the second initial attenuation path at different initial rotation angles, the measured attenuation path of the X-ray passing through the target model at different initial rotation angles is determined.

[0103] Specifically, in the interval where the path length of the X-ray passing through the phantom varies greatly between two adjacent rotation angles, some minor errors in the prepared phantom, such as the processing error of the phantom size and the fitting error of the phantom eccentric position, will cause a large change in the mapping relationship. In addition, since the phantoms all have a shell made of non-aqueous material, the proportion of the shell made of non-aqueous material in these intervals is relatively large, which will also cause a large change in the mapping relationship. In order to reduce the impact of such errors and improve the accuracy and stability of the algorithm, we can eliminate the data in these intervals. This solution adopts the following elimination method: in step S120, the first attenuation path of the X-ray passing through the first phantom and the second attenuation path of the X-ray passing through the second phantom at different rotation angles are calculated respectively, firstly, the first attenuation path of the first phantom is selected, the first attenuation path of the first phantom is compared with the first preset attenuation path, and the first attenuation path whose first attenuation path is greater than the first preset attenuation path is selected to form a first initial attenuation path, and the second attenuation path of the second phantom is selected, the second attenuation path of the second phantom is compared with the second preset attenuation path, and the second attenuation path whose second attenuation path is greater than the second preset attenuation path is selected to form a second initial attenuation path, and then the first initial rotation angle corresponding to the first initial attenuation path and the second initial rotation angle corresponding to the second initial attenuation path are obtained, and then the intersection of the first initial rotation angle and the second initial rotation angle is obtained to obtain the initial rotation angle, and finally the first target attenuation path corresponding to the initial rotation angle is screened out from the first initial attenuation path, and the second target attenuation path corresponding to the initial rotation angle is screened out from the second initial attenuation path, and then the first target attenuation path and the second target attenuation path at the same initial rotation angle are summed to obtain the measured attenuation path of the X-ray passing through the target phantom at different initial rotation angles.

[0104] It should be noted that the first preset attenuation path is determined based on the diameter of the first model body and the wide window factor, and the second preset attenuation path is determined based on the diameter of the second model body and the wide window factor.

[0105] By screening the measured attenuation path, the screened data can improve the accuracy of hardening correction and nonlinear correction and improve image quality.

[0106] Based on the above embodiments, Figure 2 is a schematic structural diagram of a CT scan system error correction device provided by an embodiment of the present disclosure. As Figure 2 shown, the CT scan system error correction device includes:

[0107] A first attenuation data determination module 210, configured to determine first attenuation data of a target phantom based on multi-energy X-rays at different rotation angles, where the target phantom includes a first phantom and a second phantom, and the centers of the first phantom and the second phantom do not overlap with the rotation center;

[0108] A measurement attenuation path determination module 220, configured to calculate a first attenuation path of X-rays passing through the first phantom and a second attenuation path of X-rays passing through the second phantom at different rotation angles, and determine a measurement attenuation path of X-rays passing through the target phantom at different rotation angles according to the first attenuation path and the second attenuation path;

[0109] A second attenuation data determination module 230, configured to determine second attenuation data of mono-energy X-rays passing through the target phantom at different rotation angles according to the measurement attenuation path and a conversion factor between attenuation data and the attenuation path under mono-energy X-rays;

[0110] A target attenuation data association module 240, configured to determine a first target attenuation data and a second target attenuation data at a target measurement attenuation path according to the first attenuation data and the second attenuation data;

[0111] A mapping function determination module 250, configured to determine a mapping function between mono-energy X-ray attenuation data and multi-energy X-ray attenuation data at different target measurement attenuation paths according to the first target attenuation data and the second target attenuation data at the target measurement attenuation path.

[0112] The CT scan system error correction device provided by the embodiments of the present disclosure first determines the first attenuation data of the target phantom based on multi - energy X - rays at different rotation angles; and calculates the first attenuation path of the X - rays passing through the first phantom and the second attenuation path of the X - rays passing through the second phantom at different rotation angles, and determines the measured attenuation path of the X - rays passing through the target phantom at different rotation angles according to the first attenuation path and the second attenuation path; then determines the second attenuation data of the mono - energy X - rays passing through the target phantom at different rotation angles according to the measured attenuation path and the conversion factor between the attenuation data and the attenuation path under mono - energy X - rays; further determines the first target attenuation data and the second target attenuation data at the target measured attenuation path according to the first attenuation data and the second attenuation data; finally determines the mapping function between the mono - energy X - ray attenuation data and the multi - energy X - ray attenuation data at different target measured attenuation paths according to the first target attenuation data and the second target attenuation data at the target measured attenuation path. It realizes the correction of multi - energy X - ray attenuation to mono - energy X - ray attenuation under the same path. While realizing beam hardening correction, since the same mono - energy attenuation coefficient is selected in the process of establishing the mapping from multi - energy X - rays to mono - energy X - rays for all detector channels, this mapping also realizes the correction of detector response consistency; in addition, the information of the tube spectrum and the filtration system is not applicable in the process of realizing beam hardening correction and detector response consistency correction. Therefore, when the tube spectrum or the filtration system changes significantly, such as the filtration deflects during installation, this correction algorithm is still effective.

[0113] In a specific embodiment, the determining the first attenuation data of the target phantom based on multi - energy X - rays at different rotation angles includes:

[0114] Obtaining the initial attenuation data of the target phantom based on multi - energy X - rays at different rotation angles, where the initial attenuation data includes detector channels and scan angles;

[0115] Obtaining air attenuation data;

[0116] Correcting the initial attenuation data based on the air attenuation data to obtain the first attenuation data.

[0117] In a specific embodiment, the determining the measured attenuation path of the X - rays passing through the target phantom at different rotation angles according to the first attenuation path and the second attenuation path includes:

[0118] Summing the first attenuation path of the X - rays passing through the first phantom and the second attenuation path of the X - rays passing through the second phantom at the same rotation angle to obtain the initial measured attenuation path of the X - rays passing through the target phantom at different rotation angles;

[0119] Process the initial measured attenuation path according to the relationship between the first attenuation data and the preset attenuation data to obtain the measured attenuation path.

[0120] In a specific embodiment, the process of processing the initial measured attenuation path according to the relationship between the first attenuation data and the preset attenuation data to obtain the measured attenuation path includes:

[0121] When the pulse width of the first attenuation data is different from the pulse width of the preset attenuation data, determine the adjustment distances from the centers of the first phantom and the second phantom to the rotation center;

[0122] When the timing of the pulse peak of the first attenuation data is different from the timing of the pulse peak of the preset attenuation data, determine the adjustment deflection angles of the centers of the first phantom and the second phantom;

[0123] Adjust the initial measured attenuation path according to the adjustment distances and adjustment deflection angles to obtain the measured attenuation path.

[0124] In a specific embodiment, the process of determining the first target attenuation data and the second target attenuation data under the target measured attenuation path according to the first attenuation data and the second attenuation data includes:

[0125] Obtain the first correlation relationship between the first attenuation data and the rotation angle, the second correlation relationship between the second attenuation data and the rotation angle, and the third correlation relationship between the measured attenuation path and the rotation angle;

[0126] According to the first correlation relationship between the first attenuation data and the rotation angle, the second correlation relationship between the second attenuation data and the rotation angle, the third correlation relationship between the measured attenuation path and the rotation angle, the first attenuation data, and the second attenuation data, determine the first target attenuation data and the second target attenuation data under the target measured attenuation path.

[0127] In a specific embodiment, before determining the mapping function between the monoenergetic X-ray attenuation data and the polyenergetic X-ray attenuation data under different target measured attenuation paths according to the first target attenuation data and the second target attenuation data under the target measured attenuation path, it further includes:

[0128] Determine the first initial attenuation path according to the relationship between the first attenuation path and the first preset attenuation path, and determine the second initial attenuation path according to the relationship between the second attenuation path and the second preset attenuation path;

[0129] Determine the first initial rotation angle corresponding to the first initial attenuation path, and determine the second initial rotation angle corresponding to the second target attenuation;

[0130] Determine an initial rotation angle based on the first initial rotation angle and the second initial rotation angle;

[0131] Determine the measured attenuation path of X-rays passing through the target phantom at different initial rotation angles based on the first initial attenuation path and the second initial attenuation path at different initial rotation angles.

[0132] In a specific embodiment, it further includes:

[0133] In response to receiving the multi-energy X-ray attenuation data of the test phantom at the test angle, determine the mono-energy X-ray attenuation data of the test phantom at the test angle according to the mapping function between the mono-energy X-ray attenuation data and the multi-energy X-ray attenuation data under the target measured attenuation path;

[0134] Perform back-projection reconstruction based on the mono-energy X-ray attenuation data of the test phantom at different test angles to obtain a scanned image.

[0135] The embodiment of the present application also provides a computer device. Specifically, please refer to Figure 3 , Figure 3 which is the basic structural block diagram of the computer device in this embodiment.

[0136] The computer device includes a memory 510 and a processor 520 that communicate with each other through a system bus. It should be noted that only the computer device with components 510 - 520 is shown in the figure. However, it should be understood that it is not required to implement all the shown components, and more or fewer components can be implemented alternatively. Among them, those skilled in the art of the present technology can understand that the computer device here is a device that can automatically perform numerical calculations and / or information processing according to pre-set or stored instructions, and its hardware includes but is not limited to microprocessors, application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), embedded devices, etc.

[0137] The computer device can be a desktop computer, a notebook, a palm computer, a cloud server, and other computing devices. The computer device can perform human-computer interaction with users through means such as a keyboard, a mouse, a remote control, a touchpad, or a voice control device.

[0138] The memory 510 includes at least one type of readable storage medium, and the readable storage medium includes non-volatile memory or volatile memory, such as flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory, etc.), random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, magnetic disk, optical disc, etc. The RAM may include static RAM or dynamic RAM. In some embodiments, the memory 510 may be an internal storage unit of the computer device, for example, the hard disk or memory of the computer device. In other embodiments, the memory 510 may also be an external storage device of the computer device, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the computer device. Of course, the memory 510 may also include both the internal storage unit and the external storage device of the computer device. In this embodiment, the memory 510 is generally used to store the operating system and various application software installed on the computer device, such as the program code of the above method. In addition, the memory 510 may also be used to temporarily store various data that have been output or will be output.

[0139] The processor 520 is generally used to execute the overall operations of the computer device. In this embodiment, the memory 510 is used to store program code or instructions, and the program code includes computer operation instructions. The processor 520 is used to execute the program code or instructions stored in the memory 510 or process data, such as running the program code of the above method.

[0140] In this document, the bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The bus system can be divided into an address bus, a data bus, a control bus, etc. For the sake of simplicity in illustration, only a thick line is used in the figure to represent it, but it does not mean that there is only one bus or one type of bus.

[0141] Another embodiment of the present application further provides a computer-readable medium, which can be a computer-readable signal medium or a computer-readable storage medium. The processor in the computer reads the computer-readable program code stored in the computer-readable medium, so that the processor can perform the functional actions specified in each step or the combination of steps in the above method; and generate a device that implements the functional actions specified in each block or the combination of blocks in the block diagram.

[0142] The computer-readable medium includes but is not limited to electronic, magnetic, optical, electromagnetic, infrared memories or semiconductor systems, devices or apparatuses, or any suitable combination of the foregoing. The memory is used to store program code or instructions, and the program code includes computer operation instructions. The processor is used to execute the program code or instructions of the above method stored in the memory.

[0143] For the definitions of the memory and the processor, reference can be made to the description of the foregoing computer device embodiments, and details are not described herein again.

[0144] In several embodiments provided by the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of modules or units is only a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection to each other can be through some interfaces. The indirect coupling or communication connection of the device or unit can be in an electrical, mechanical or other form.

[0145] In each embodiment of the present application, each functional unit or module can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0146] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor to execute all or part of the steps of the methods of various embodiments of this application. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM), random access memories (RAM), magnetic disks, or optical discs.

[0147] Unless the context clearly indicates otherwise, the singular forms of the words used in this specification and the appended claims include the plural, and vice versa. Thus, when referring to the singular, the plural of the corresponding term is usually included. Similarly, the terms "comprising" and "including" shall be interpreted as inclusive rather than exclusive. Likewise, the term "including" and "or" shall be interpreted as inclusive, unless such an interpretation is explicitly prohibited in this specification. Where the term "example" is used in this specification, especially when it is located after a group of terms, the "example" is merely exemplary and illustrative and should not be considered exclusive or extensive.

[0148] Further aspects and scopes of adaptability become apparent from the description provided herein. It should be understood that the various aspects of this application can be implemented alone or in combination with one or more other aspects. It should also be understood that the description and specific embodiments herein are for illustrative purposes only and are not intended to limit the scope of this application.

[0149] The above has described several embodiments of the present disclosure in detail. However, obviously, those skilled in the art can make various modifications and variations to the embodiments of the present disclosure without departing from the spirit and scope of the present disclosure. The protection scope of the present disclosure is defined by the appended claims.

Claims

1. A CT scanning system error correction method, characterized in that: include: Determine first attenuation data of a target phantom based on multi-energy X-rays at different rotation angles, wherein the target phantom includes a first phantom and a second phantom, and centers of the first phantom and the second phantom do not overlap with a rotation center; Calculating a first attenuation path of the X-ray passing through the first phantom and a second attenuation path of the X-ray passing through the second phantom at different rotation angles, and determining a measured attenuation path of the X-ray passing through the target phantom at different rotation angles according to the first attenuation path and the second attenuation path; Determine second attenuation data of the monoenergetic X-ray passing through the target phantom at different rotation angles according to the measured attenuation path and a conversion factor between the attenuation data and the attenuation path under the monoenergetic X-ray, wherein the conversion factor is an attenuation coefficient; Determine first target attenuation data and second target attenuation data under a target measurement attenuation path according to the first attenuation data and the second attenuation data; A mapping function between the mono-energy X-ray attenuation data and the poly-energy X-ray attenuation data under different target measurement attenuation paths is determined according to the first target attenuation data and the second target attenuation data under the target measurement attenuation path.

2. The method according to claim 1, characterized in that The determining of first attenuation data of the target phantom based on multi-energy X-rays at different rotation angles includes: Acquire initial attenuation data of the target phantom based on multi-energy X-rays at different rotation angles, wherein the initial attenuation data includes a detector channel and a scanning angle; Obtain air attenuation data; The initial attenuation data is corrected based on the air attenuation data to obtain first attenuation data.

3. The method according to claim 1, characterized in that The step of determining, according to the first attenuation path and the second attenuation path, a measurement attenuation path of X-rays passing through the target phantom at different rotation angles includes: Summing a first attenuation path of the X-ray passing through the first phantom and a second attenuation path of the X-ray passing through the second phantom at the same rotation angle to obtain an initial measured attenuation path of the X-ray passing through the target phantom at different rotation angles; According to the relationship between the first attenuation data and the preset attenuation data, the initial measured attenuation path is processed to obtain a measured attenuation path, wherein the preset attenuation data is attenuation data generated based on monoenergetic X-rays at different rotation angles at a preset position of the target phantom.

4. The method according to claim 3, characterized in that The processing of the initial measured attenuation path to obtain the measured attenuation path according to the relationship between the first attenuation data and the preset attenuation data includes: When the pulse width of the first attenuation data is different from the pulse width of the preset attenuation data, determining an adjustment distance from the first mold body center and the second mold body center to the rotation center; When the timing of the pulse peak of the first attenuation data is different from the timing of the pulse peak of the preset attenuation data, determining the adjustment deflection angle of the first phantom circle center and the second phantom circle center; According to the adjustment distance and the adjustment deflection angle, the initial measurement attenuation path is adjusted to obtain a measurement attenuation path.

5. The method according to claim 1, characterized in that The determining, according to the first attenuation data and the second attenuation data, first target attenuation data and second target attenuation data under the target measurement attenuation path comprises: Acquire a first correlation between the first attenuation data and the rotation angle, a second correlation between the second attenuation data and the rotation angle, and a third correlation between the measured attenuation path and the rotation angle; According to the first correlation between the first attenuation data and the rotation angle, the second correlation between the second attenuation data and the rotation angle, and the third correlation between the measured attenuation path and the rotation angle, the first attenuation data and the second attenuation data determine the first target attenuation data and the second target attenuation data under the target measured attenuation path.

6. The method according to claim 1, characterized in that Before determining the mapping function between the monoenergetic X-ray attenuation data and the polyenergetic X-ray attenuation data under different target measurement attenuation paths according to the first target attenuation data and the second target attenuation data under the target measurement attenuation path, the method further includes: Determine a first initial attenuation path according to a relationship between the first attenuation path and a first preset attenuation path, and determine a second initial attenuation path according to a relationship between the second attenuation path and a second preset attenuation path; Determining a first initial rotation angle corresponding to the first initial attenuation path, and determining a second initial rotation angle corresponding to the second target attenuation; Determining an initial rotation angle according to the first initial rotation angle and the second initial rotation angle; According to the first initial attenuation path and the second initial attenuation path at different initial rotation angles, a measurement attenuation path of the X-ray passing through the target phantom at different initial rotation angles is determined.

7. The method according to claim 1, characterized in that Also includes: In response to receiving the multi-energy X-ray attenuation data of the test phantom at the test angle, determining the single-energy X-ray attenuation data of the test phantom at the test angle according to a mapping function between the single-energy X-ray attenuation data and the multi-energy X-ray attenuation data in the target measurement attenuation path; According to the monoenergetic X-ray attenuation data of the test phantom at different test angles, back-projection reconstruction is performed to obtain the scanned image.

8. A CT scanning system error correction device, characterized in that: include: A first attenuation data determination module is used to determine first attenuation data of a target phantom based on multi-energy X-rays at different rotation angles, wherein the target phantom includes a first phantom and a second phantom, and the centers of the first phantom and the second phantom do not overlap with the rotation center; a measurement attenuation path determination module, configured to calculate a first attenuation path of the X-ray passing through the first phantom and a second attenuation path of the X-ray passing through the second phantom at different rotation angles, and determine a measurement attenuation path of the X-ray passing through the target phantom at different rotation angles according to the first attenuation path and the second attenuation path; A second attenuation data determination module is used to determine second attenuation data of the monoenergetic X-ray passing through the target phantom at different rotation angles according to the measured attenuation path and a conversion factor between the attenuation data and the attenuation path under the monoenergetic X-ray, wherein the conversion factor is an attenuation coefficient; a target attenuation data associating module, configured to determine first target attenuation data and second target attenuation data under a target measurement attenuation path according to the first attenuation data and the second attenuation data; The mapping function determination module is used to determine the mapping function between the monoenergetic X-ray attenuation data and the polyenergetic X-ray attenuation data under different target measurement attenuation paths according to the first target attenuation data and the second target attenuation data under the target measurement attenuation path.

9. A computer device, characterized in that: include: one or more processors; a storage device for storing one or more programs, When the one or more programs are executed by the one or more processors, the one or more processors implement the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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