Receiving apodization method and device for three-dimensional ultrasonic synthetic aperture imaging, medium and equipment

Abstract

The invention provides a receiving apodization method and device for three-dimensional ultrasonic synthetic aperture imaging, a medium and equipment. The method comprises the following steps: 1, determining the position of a transmitting transducer, and the positions, orientations and three-dimensional main lobe ranges of all receiving transducers; 2, determining a first multiplier of an apodization coefficient of each receiving transducer according to a main lobe sensitivity principle for a pixel point in an imaging view field; 3, for the pixel point, determining a second multiplier of the apodization coefficient of each receiving transducer according to a backscattering principle; 4, for the pixel point, completing beam forming by using the first multiplier and the second multiplier of the obtained apodization coefficient; and 5, repeating the steps 2, 3 and 4 to complete beam synthesis of all pixel points in the imaging view field. According to the invention, the overall quality of three-dimensional ultrasonic synthetic aperture imaging can be improved.

Description

Technical Field

[0001] The present application relates to the field of ultrasonic imaging technology, and in particular to a receiving apodization method, device, medium and equipment for three-dimensional ultrasonic synthetic aperture imaging. Background Art

[0002] Ultrasonic imaging technology has a wide range of applications in deep-sea exploration, non-destructive testing, medical diagnosis and other fields. With the continuous development of technology, three-dimensional ultrasonic imaging modality has been widely studied and gradually put into different application scenarios. Three-dimensional ultrasonic imaging can provide more intuitive and reliable spatial information than two-dimensional imaging, and has extremely high practical value.

[0003] In the beam synthesis process of ultrasound imaging, apodization design plays a role in optimizing beam morphology and improving imaging quality. Unreasonable apodization will affect the resolution and contrast of ultrasound images, reduce the overall quality of imaging, and limit the practical value of three-dimensional ultrasound imaging technology. Summary of the invention

[0004] The purpose of the present application is to provide a receiving apodization method, device, medium and equipment for three-dimensional ultrasonic synthetic aperture imaging, which can at least partially solve the above-mentioned technical problems existing in the prior art.

[0005] One aspect of the present application provides a receiving apodization method for three-dimensional ultrasonic synthetic aperture imaging. The method includes: step 1: determining the position of the transmitting transducer, and the position, orientation and three-dimensional main lobe range of all receiving transducers; step 2: for a pixel point in the imaging field of view, determining the first multiplier of the apodization coefficient of each receiving transducer according to the main lobe sensitivity principle; step 3: for the pixel point, determining the second multiplier of the apodization coefficient of each receiving transducer according to the backscattering principle; step 4: for the pixel point, using the first multiplier and the second multiplier of the obtained apodization coefficient to complete beam synthesis; step 5: repeating steps 2, 3 and 4 to complete beam synthesis of all pixel points in the imaging field of view.

[0006] Further, determining the first multiplier of the apodization coefficient of each receiving transducer according to the main lobe sensitivity principle includes: determining the first multiplier of the apodization coefficient of each receiving transducer by the following formula:

[0007] in, Represents the three-dimensional coordinate vector of the pixel point, Representative The three-dimensional coordinate vector of the receiving transducer, Represents the pixel No. The first multiplier of the apodization coefficient of the receiving transducer, Representative The three-dimensional main lobe range of a receiving transducer.

[0008] Furthermore, the three-dimensional main lobe range of each receiving transducer is approximately determined by an ellipsoid formed by the main lobe angle of each receiving transducer in the azimuth plane and the main lobe angle of each receiving transducer in the elevation plane.

[0009] Furthermore, the method further comprises: determining a pixel point Is there any The 3D main lobe of the receiving transducer includes: by is the origin, , , Establish a local coordinate system for the coordinate axes, where , and Respectively represent A three-dimensional main lobe azimuth plane positive direction vector, a pitch plane positive direction vector and a heading vector of a receiving transducer; Counting pixels exist The coordinates in the local coordinate system of , , :

[0010]

[0011]

[0012] Calculate the depth of the ellipsoid Long axis of the lower elliptical slice With short axis :

[0013]

[0014] in, and Respectively represent The main lobe angle of the receiving transducer in the azimuth plane and the main lobe angle of the elevation plane; Determine whether the following formula is true:

[0015] If true, then determine the pixel Exists in The three-dimensional main lobe range of the receiving transducer, otherwise, the pixel point is determined Exists in outside the 3D main lobe of the receiving transducer.

[0016] Furthermore, the receiving transducer comprises a circular transducer array element or a square transducer array element, wherein a three-dimensional main lobe range of the receiving transducer is approximately determined by a cone.

[0017] Further, determining the second multiplier of the apodization coefficient of each receiving transducer according to the backscattering principle includes: determining the second multiplier of the apodization coefficient of each receiving transducer by the following formula:

[0018]

[0019] in, Represents the three-dimensional coordinate vector of the pixel point, Representative The three-dimensional coordinate vector of the receiving transducer, Represents the pixel No. The second multiplier of the apodization coefficient of the receiving transducer, Represents pixel The launch vector and The inner product of the received vectors, Represents the position of the transmitting transducer.

[0020] Further, the first multiplier and the second multiplier using the obtained apodization coefficients complete beamforming through the following formula:

[0021]

[0022] in, Represents pixel The pixel value at represents the total number of receiving transducers, and Represents the pixels No. said first multiplier and said second multiplier of the apodization coefficient of a receiving transducer, Representative A signal from a receiving transducer, Representative The receiving transducer is connected to the pixel point The delay of receiving the echo, represents the position of the transmitting transducer, Represents the speed of sound.

[0023] Another aspect of the present application provides a receiving apodization device for three-dimensional ultrasonic synthetic aperture imaging. The device includes a first determination module, a second determination module, a third determination module, a first beam synthesis module and a second beam synthesis module. The first determination module is used to determine the position of the transmitting transducer, and the position, orientation and three-dimensional main lobe range of all receiving transducers. The second determination module is used to determine the first multiplier of the apodization coefficient of each receiving transducer according to the main lobe sensitivity principle for each pixel point in the imaging field of view. The third determination module is used to determine the second multiplier of the apodization coefficient of each receiving transducer according to the backscattering principle for each pixel point in the imaging field of view. The first beam synthesis module is used to perform beam synthesis for each pixel point in the imaging field of view using the first multiplier and the second multiplier of the obtained apodization coefficient. The second beam synthesis module is used to perform beam synthesis on all pixel points in the imaging field of view.

[0024] Another aspect of the present application provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the above method when executed by a processor.

[0025] Another aspect of the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the above method are implemented.

[0026] The receiving apodization method, device, medium and apparatus for three-dimensional ultrasonic synthetic aperture imaging according to one or more embodiments of the present application may have at least the following beneficial technical effects: (1) The apodization coefficient ensures that the pixel point always falls within the three-dimensional main lobe range of the receiving transducer, avoiding the contribution of the transducer receiving signal to the beam synthesis of the pixel points outside the main lobe area, thereby ensuring the final ultrasound image quality; (2) The apodization coefficient ensures that only the backscattered signal is used for beam synthesis, avoiding the forward scattered signal from contributing to the beam synthesis and causing unnecessary image artifacts, thereby ensuring the final ultrasound image quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The figure is a flow chart of a receiving apodization method for three-dimensional ultrasonic synthetic aperture imaging according to an embodiment of the present application.

[0028] Figure 2 It is a schematic diagram of the spatial relationship between the ellipsoidal approximation of the three-dimensional main lobe range of the receiving transducer of one embodiment of the present application, the main lobe angle in the azimuth plane, and the main lobe angle in the elevation plane.

[0029] Figure 3This is a comparative schematic diagram of a receiving transducer receiving a backscattered signal and a forward scattered signal according to an embodiment of the present application.

[0030] Figure 4 A schematic diagram of a receiving apodization device for three-dimensional ultrasonic synthetic aperture imaging according to an embodiment of the present application.

[0031] Figure 5 A schematic block diagram of an electronic device according to an embodiment of the present application. DETAILED DESCRIPTION

[0032] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Instead, they are merely examples of devices consistent with some aspects of the present application as detailed in the appended claims.

[0033] In ultrasonic imaging, receive apodization is a method of assigning different weights (weighted processing) to different element signals in an array to optimize the spatial shape and characteristics of the beam. Depending on the needs, receive apodization can achieve different purposes, including reducing the sidelobe level, improving the main lobe width, improving the resolution, reducing the dynamic range, etc. In two-dimensional imaging, since the ultrasonic transducer array is simple in concept (generally a linear array), dynamic apodization that adjusts with depth is generally used. However, in three-dimensional imaging, the spatial arrangement of the ultrasonic transducer array is often more complex, and the dynamic apodization of traditional two-dimensional ultrasonic imaging is no longer applicable. Therefore, the present application provides a receive apodization method for three-dimensional ultrasonic synthetic aperture imaging.

[0034] The following is a detailed description of the receiving apodization method, device, medium and equipment for three-dimensional ultrasonic synthetic aperture imaging according to various embodiments of the present application in conjunction with the accompanying drawings. In the absence of conflict, the features of the following embodiments and implementations may be combined with each other.

[0035] Figure 1 A flowchart of a receiving apodization method for three-dimensional ultrasonic synthetic aperture imaging according to an embodiment of the present application is disclosed. Figure 1 As shown, a receiving apodization method for three-dimensional ultrasonic synthetic aperture imaging according to an embodiment of the present application may include steps S1 to S6.

[0036] Step S1: Determine the position of the transmitting transducer, and the positions, orientations, and three-dimensional main lobe ranges of all receiving transducers.

[0037] Synthetic aperture imaging refers to a technique that uses a single transducer to transmit, multiple transducers to receive and beamform each time, and then synthesizes the results obtained by multiple transmitting transducers to simulate large-aperture transmit imaging. Due to the use of independent transmission, synthetic aperture imaging technology has no special requirements for the spatial distribution and transmission mode of the transmitting array elements. Therefore, synthetic aperture imaging can essentially be divided into the beamforming problem of each independent transmitting transducer. The following application will expand on the basic situation of beamforming and dynamic tracking of single transducer transmission, without making any assumptions about the positions of the transmitting and receiving transducers. Therefore, this application can be applied to three-dimensional synthetic aperture imaging of arrays of arbitrary shapes.

[0038] Determine the location of the transmitting transducer to Indicates the location of the transmitting transducer.

[0039] Determine the location and orientation of all receiving transducers to Indicates The three-dimensional space coordinate vector of the receiving transducer is Indicates The positive direction vector of the three-dimensional main lobe azimuth plane of the receiving transducer is Indicates The positive direction vector of the three-dimensional main lobe elevation plane of the receiving transducer is Indicates The three-dimensional main lobe orientation vector of the receiving transducer.

[0040] Determine the three-dimensional mainlobe extents of all receiving transducers. Figure 2 The present invention discloses an ellipsoidal approximation of the three-dimensional main lobe range of the receiving transducer, a schematic diagram of the spatial relationship between the main lobe angle in the azimuth plane and the main lobe angle in the elevation plane, wherein the ellipsoidal approximation of the three-dimensional main lobe range of the receiving transducer is as follows: Figure 2 As shown in the left figure, the main lobe angle in azimuth is Figure 2 As shown in the middle figure, the main lobe angle in the elevation plane is Figure 2 As shown in the right figure. Figure 2 As shown, the main lobe angle of each receiving transducer in the azimuth plane and the main lobe angle in the pitch plane The ellipsoid formed by the three-dimensional main lobe of each receiving transducer is used to approximate the range of the three-dimensional main lobe of each receiving transducer. The main lobe angle is generally taken as the beam intensity of the transducer in a given plane. The angle range formed by the boundary.

[0041] For a receiving transducer including circular or square transducer array elements, the three-dimensional main lobe range of the receiving transducer can be approximated by a standard cone.

[0042] Of course, the three-dimensional main lobe range of the receiving transducer of the present application is not limited to being determined by the method described above, and may also be determined by other methods.

[0043] Step S2: for a pixel point in the imaging field of view, determine the first multiplier of the apodization coefficient of each receiving transducer according to the main lobe sensitivity principle.

[0044] In some embodiments, the first multiplier of each receiving transducer apodization coefficient may be determined by the following formula (1): (1) in, Represents the three-dimensional coordinate vector of the pixel point, Representative The three-dimensional coordinate vector of the receiving transducer, Represents the pixel No. The first multiplier of the apodization coefficient of the receiving transducer, Representative The three-dimensional main lobe range of a receiving transducer.

[0045] Step S2 may include: determining the pixel point Is there any The three-dimensional main lobe range of a receiving transducer.

[0046] The following describes in detail how to determine the pixel Is there any The three-dimensional main lobe of the receiving transducer.

[0047] The main lobe angle of each receiving transducer in the azimuth plane and the main lobe angle in the pitch plane The pixel point is determined by using the ellipsoid to approximate the three-dimensional main lobe range of each receiving transducer. Is there any The three-dimensional main lobe range of a receiving transducer may include steps S21 to S24.

[0048] Step S21: is the origin, , , Establish a local coordinate system for the coordinate axes, where , and Respectively represent The three-dimensional main lobe azimuth plane positive direction vector, elevation plane positive direction vector and heading vector of a receiving transducer.

[0049] Step S22: Calculate the pixel points according to the following formula (2): exist The coordinates in the local coordinate system of , , : (2) in, A three-dimensional coordinate vector representing a pixel point.

[0050] Step S23: Calculate the depth of the ellipsoid according to the following formula (3): Long axis of the lower elliptical slice With short axis : (3) in, and Respectively represent The main lobe angle of a receiving transducer in the azimuth plane and the main lobe angle of the elevation plane.

[0051] Step S24: Determine whether the following formula (4) is true: (4) If the above formula (4) holds, then the pixel point Exists in Within the three-dimensional main lobe range of the receiving transducer, that is Otherwise, the pixel is determined Exists in outside the three-dimensional main lobe range of the receiving transducer, that is, .

[0052] Step S3: for the pixel point, determine the second multiplier of the apodization coefficient of each receiving transducer according to the backscattering principle.

[0053] In some embodiments, the second multiplier of each receiving transducer apodization coefficient may be determined by the following formula (5): (5) in, Represents the three-dimensional coordinate vector of the pixel point, Representative The three-dimensional coordinate vector of the receiving transducer, Represents the pixel No. The second multiplier of the apodization coefficient of the receiving transducer, Represents pixel The launch vector and The inner product of the received vectors can be given by the following formula (6): (6) in, Represents the position of the transmitting transducer.

[0054] Figure 3 A comparison diagram of a receiving transducer receiving a backscattered signal and a forward scattered signal according to an embodiment of the present application is disclosed, wherein the receiving transducer receives a backscattered signal such as Figure 3 As shown in the left diagram, the receiving transducer receives the forward scattered signal as Figure 3 As shown in the figure on the right.

[0055] Step S4: for the pixel point, beam synthesis is completed by using the first multiplier of the apodization coefficient obtained in step S2 and the second multiplier of the apodization coefficient obtained in step S3.

[0056] In some embodiments, beamforming can be performed using the first multiplier and the second multiplier of the obtained apodization coefficients through the following formula (7): (7) in, Represents pixel The pixel value at represents the total number of receiving transducers, and Represents the pixels No. The first and second multipliers of the apodization coefficients of the receiving transducers, Representative A signal from a receiving transducer, Representative The receiving transducer is connected to the pixel point The echo reception delay can be given by the following formula (8): (8) in, represents the position of the transmitting transducer, Represents the speed of sound.

[0057] Step S5: Determine whether the pixel is the last pixel in the imaging field of view. If the result of the determination is "yes", the process proceeds to step S6. Otherwise, the above steps S2, S3 and S4 are repeated for the next pixel in the imaging field of view.

[0058] In step S6, beam synthesis of all pixels in the imaging field of view is completed.

[0059] Understandably, Figure 1 The steps S1 to S6 shown are only names given to the steps for distinguishing each other, and do not represent the order in which the steps are executed.

[0060] The receiving apodization method of the three-dimensional ultrasonic synthetic aperture imaging of the present application can design dynamic receiving apodization according to the main lobe sensitivity and backscattering principle to improve the resolution and contrast of imaging of a single transmitting transducer, thereby improving the overall quality and practical value of the three-dimensional ultrasonic synthetic aperture imaging.

[0061] The above is the receiving apodization method for three-dimensional ultrasonic synthetic aperture imaging provided by the present application. Based on the same idea, the present application also provides a corresponding receiving apodization device for three-dimensional ultrasonic synthetic aperture imaging. Figure 4 A schematic diagram of a receiving apodization device 400 for three-dimensional ultrasonic synthetic aperture imaging according to an embodiment of the present application is disclosed. Figure 4 As shown, a receiving apodization device 400 for three-dimensional ultrasonic synthetic aperture imaging according to an embodiment of the present application may include a first determination module 401 , a second determination module 402 , a third determination module 403 , a first beamforming module 404 and a second beamforming module 405 .

[0062] The first determination module 401 is used to determine the position of the transmitting transducer, and the positions, directions and three-dimensional main lobe ranges of all receiving transducers.

[0063] The second determination module 402 is used to determine the first multiplier of the apodization coefficient of each receiving transducer according to the main lobe sensitivity principle for each pixel point in the imaging field of view.

[0064] The third determination module 403 is used to determine the second multiplier of the apodization coefficient of each receiving transducer according to the backscattering principle for each pixel point in the imaging field of view.

[0065] The first beamforming module 404 is used to perform beamforming for each pixel point in the imaging field of view using the first multiplier and the second multiplier of the obtained apodization coefficient.

[0066] The second beamforming module 405 is used to perform beamforming on all pixel points in the imaging field of view.

[0067] The present application also provides a computer-readable storage medium. The storage medium stores a computer program, which, when executed by a processor, implements the above Figure 1 The steps of the receiving apodization method for three-dimensional ultrasonic synthetic aperture imaging are shown.

[0068] The present application also provides an electronic device 500 . Figure 5 A schematic block diagram of an electronic device 500 according to an embodiment of the present application is disclosed. Figure 5 As shown, an electronic device 500 of an embodiment of the present application includes a processor 501, an internal bus 502, a network interface 503, a memory 504 and a non-volatile memory 505, and may also include hardware required for other services. The processor 501 can read the corresponding computer program from the non-volatile memory 505 into the memory 504 and then run it to implement the steps of the receiving tracking method of three-dimensional ultrasonic synthetic aperture imaging as described above. Of course, in addition to the software implementation, the present application does not exclude other implementation methods, such as logic devices or a combination of software and hardware, etc., that is to say, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic components.

[0069] It is understandable that, for the convenience of description, the above device is described by dividing the functions into modules. Of course, when implementing the present application, the functions of each module can also be implemented in the same or multiple software and / or hardware.

[0070] The receiving apodization method, device, medium and apparatus for three-dimensional ultrasonic synthetic aperture imaging according to one or more embodiments of the present application may have at least the following beneficial technical effects: (1) The apodization coefficient ensures that the pixel point always falls within the three-dimensional main lobe range of the receiving transducer, avoiding the contribution of the transducer receiving signal to the beam synthesis of the pixel points outside the main lobe area, thereby ensuring the final ultrasound image quality; (2) The apodization coefficient ensures that only the backscattered signal is used for beam synthesis, avoiding the forward scattered signal from contributing to the beam synthesis and causing unnecessary image artifacts, thereby ensuring the final ultrasound image quality.

[0071] The above is a detailed introduction to the receiving apodization method, device, medium and equipment for three-dimensional ultrasonic synthetic aperture imaging provided in the embodiments of the present application. This article uses specific examples to illustrate the receiving apodization method, device, medium and equipment for three-dimensional ultrasonic synthetic aperture imaging in the embodiments of the present application. The description of the above embodiments is only used to help understand the core idea of ​​the present application and is not intended to limit the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the spirit and principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications should also fall within the scope of protection of the claims attached to the present application.

Claims

1. A receiving apodization method for three-dimensional ultrasonic synthetic aperture imaging, characterized in that: include: Step 1: Determine the position of the transmitting transducer, and the position, orientation, and three-dimensional main lobe range of all receiving transducers; Step 2: for a pixel point in the imaging field of view, determine the first multiplier of the apodization coefficient of each receiving transducer according to the main lobe sensitivity principle; Step 3: for the pixel point, determine the second multiplier of the apodization coefficient of each receiving transducer according to the backscattering principle; Step 4: for the pixel point, use the first multiplier and the second multiplier of the obtained apodization coefficient to complete beam synthesis; Step 5: Repeat steps 2, 3, and 4 to complete beam synthesis for all pixels in the imaging field of view.

2. The method according to claim 1, characterized in that: The first multiplier for determining the apodization coefficient of each receiving transducer according to the main lobe sensitivity principle comprises: The first multiplier for the apodization coefficient of each receiving transducer is determined by the following formula: in, Represents the three-dimensional coordinate vector of the pixel point, Representative The three-dimensional coordinate vector of the receiving transducer, Represents the pixel No. The first multiplier of the apodization coefficient of the receiving transducer, Representative The three-dimensional main lobe range of a receiving transducer.

3. The method according to claim 2, characterized in that: The three-dimensional main lobe range of each receiving transducer is approximately determined by an ellipsoid formed by the main lobe angle of each receiving transducer in the azimuth plane and the main lobe angle of each receiving transducer in the elevation plane.

4. The method according to claim 3, characterized in that: Also includes: Determine pixel Is there any The 3D main lobe of the receiving transducer includes: by is the origin, , , Establish a local coordinate system for the coordinate axes, where , and Respectively represent A three-dimensional main lobe azimuth plane positive direction vector, a pitch plane positive direction vector and a heading vector of a receiving transducer; Counting pixels exist The coordinates in the local coordinate system of , , : Calculate the depth of the ellipsoid Long axis of the lower elliptical slice With short axis : in, and Respectively represent The main lobe angle of the receiving transducer in the azimuth plane and the main lobe angle of the elevation plane; Determine whether the following formula is true: If true, then determine the pixel Exists in The three-dimensional main lobe range of the receiving transducer, otherwise, the pixel point is determined Exists in outside the 3D main lobe of the receiving transducer.

5. The method according to claim 2, characterized in that: The receiving transducer comprises a circular transducer array element or a square transducer array element, wherein a three-dimensional main lobe range of the receiving transducer is approximately determined by a cone.

6. The method according to claim 1, characterized in that: The second multiplier for determining the apodization coefficient of each receiving transducer according to the backscattering principle comprises: The second multiplier for the apodization coefficient of each receiving transducer is determined by the following formula: in, Represents the three-dimensional coordinate vector of the pixel point, Representative The three-dimensional coordinate vector of the receiving transducer, Represents the pixel No. The second multiplier of the apodization coefficient of the receiving transducer, Represents pixel The launch vector and The inner product of the received vectors, Represents the position of the transmitting transducer.

7. The method according to claim 1, characterized in that: The first multiplier and the second multiplier using the obtained apodization coefficients are used to complete beamforming through the following formula: in, Represents pixel The pixel value at represents the total number of receiving transducers, and Represents the pixels No. said first multiplier and said second multiplier of the apodization coefficient of a receiving transducer, Representative A signal from a receiving transducer, Representative The receiving transducer is connected to the pixel point The delay of receiving the echo, represents the position of the transmitting transducer, Represents the speed of sound.

8. A receiving apodization device for three-dimensional ultrasonic synthetic aperture imaging, characterized in that: include: A first determination module is used to determine the position of the transmitting transducer, and the position, orientation and three-dimensional main lobe range of all receiving transducers; A second determination module is used to determine the first multiplier of the apodization coefficient of each receiving transducer according to the main lobe sensitivity principle for each pixel point in the imaging field of view; A third determination module is used to determine the second multiplier of the apodization coefficient of each receiving transducer according to the backscattering principle for each pixel point in the imaging field of view; A first beamforming module, configured to perform beamforming for each pixel point in an imaging field of view by using the first multiplier and the second multiplier of the obtained apodization coefficient; The second beamforming module is used to perform beamforming on all pixel points in the imaging field of view.

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

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method described in any one of claims 1 to 7 are implemented.

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