Multiphase flow quasi-dynamic motif for CT equipment test and CT equipment test method

Abstract

The invention discloses a multiphase flow quasi-dynamic motif for CT equipment testing and a CT equipment testing method. The multiphase flow quasi-dynamic motif comprises a shell, a guide pipe and a multiphase flow field column. The guide pipe is arranged in the shell, the multiphase flow field column is of a solid structure, at least one bubble is distributed in the multiphase flow field column, and the multiphase flow field column is detachably arranged in the guide pipe and can move in the axial direction of the guide pipe. The multiphase flow quasi-dynamic motif simulates the flow of multiphase flow by using the movement of the multiphase flow field column in the guide tube, and can simulate most of the movement characteristics in the real multiphase flow field, thereby realizing the test of CT equipment for multiphase flow measurement. According to the CT equipment testing method, the multi-phase flow quasi-dynamic motif is utilized, and truth value data and dynamic measurement data of a multi-phase flow field can be obtained by adopting an existing measurement method, so that the CT equipment is tested.

Description

Technical Field

[0001] The present invention belongs to the field of multiphase flow technology, and in particular, relates to a multiphase flow quasi-dynamic phantom for CT equipment testing and a CT equipment testing method. Background Art

[0002] Multiphase flow is extremely complex. If we want to discover and extract scientific principles from physical phenomena, the key technical problem lies in the measurement of multiphase flow. Current multiphase flow measurement methods include high-speed photography, radiography, ultrasonic imaging, fiber optic probes, etc. These methods can quickly obtain the measurement parameters of flow field flow. With the development of technology, the time resolution and spatial resolution of flow field measurement technology have increased rapidly. One of the important technical routes is to use high-speed X-ray CT (Computed Tomography) equipment to perform three-dimensional measurement of multiphase flow fields. In order to objectively evaluate the measurement accuracy of CT equipment, the usual practice is to select a suitable test object, compare the measurement data of the CT equipment on the test object with the known true value data, and evaluate the measurement performance of the CT equipment.

[0003] In the high-temporal-spatial-resolution measurement of multiphase flow fields, the physical characteristics of multiphase flow fields determine that it is impossible to obtain two completely identical flow fields. If the actual multiphase flow field is used as the test object, the corresponding true value data cannot be obtained, which makes it impossible to reasonably evaluate the performance of the CT device in the actual multiphase flow measurement. In addition, when measuring a motion system similar to a multiphase flow field, the CT device will produce motion artifacts, which will damage the temporal-spatial resolution of the device. Therefore, it is expected to develop a technology that can simulate the dynamic effects of the multiphase flow field and obtain true value data using existing measurement methods to realize the testing of CT equipment. Summary of the invention

[0004] The present invention provides a multiphase flow quasi-dynamic phantom for CT equipment testing, comprising a housing, a guide tube, and a multiphase flow field column;

[0005] The guide tube is arranged in the shell, the multiphase flow field column is a solid structure with at least one bubble distributed inside, and the multiphase flow field column is detachably arranged in the guide tube and can move along the axial direction of the guide tube.

[0006] Preferably, the housing, the multiphase flow field column and the guide tube are all made of a polymer material that allows X-rays to penetrate; and / or

[0007] The multiphase flow field column is cylindrical, the guide tube is a round tube, and the inner diameter of the guide tube is adapted to the outer diameter of the multiphase flow field column.

[0008] Preferably, the axial direction of the guide tube is arranged along the vertical direction or forms an angle with the vertical direction, and the angle is less than or equal to 15°; and / or

[0009] The multiphase flow quasi-dynamic phantom further comprises a driving mechanism, and the multiphase flow field column is connected to the driving mechanism and can move in the guide tube along the axial direction of the guide tube under the action of the driving mechanism.

[0010] Preferably, one of the guide tubes and one of the multiphase flow field columns form a phantom unit, and the multiphase flow quasi-dynamic phantom includes a plurality of phantom units, and the plurality of phantom units are substantially evenly distributed in the housing.

[0011] The embodiment of the present invention further provides a CT equipment testing method, using the multiphase flow quasi-dynamic phantom, comprising:

[0012] Step 1: Use a reference CT device to scan the multiphase flow field column, the guide tube and the shell to obtain first static three-dimensional structure data of the multiphase flow field column and second static three-dimensional structure data of the guide tube and the shell;

[0013] Step 2: causing the multiphase flow field column to perform acceleration or deceleration movement in the guide tube, and using the CT device to be tested to scan the multiphase flow quasi-dynamic phantom to obtain dynamic measurement data of the multiphase flow quasi-dynamic phantom at multiple different speeds;

[0014] Step 3: Calculate the true value data at each speed according to the first static three-dimensional structure data and the second static three-dimensional structure data, and calculate the structural similarity index corresponding to each speed based on the true value data and the dynamic measurement data.

[0015] Preferably, the step 1 comprises:

[0016] Scanning the multiphase flow column using a reference CT device to obtain voxel format data of the multiphase flow column under a static state, and scanning the guide tube and the shell using a reference CT device to obtain voxel format data of the guide tube and the shell, wherein each voxel stores a floating point number, and the floating point number represents a density measurement value corresponding to the voxel;

[0017] The voxel format data of the multiphase flow column is binarized to obtain the first static three-dimensional structure data of the multiphase flow column, and the voxel format data of the guide tube and the shell are binarized to obtain the second static three-dimensional structure data of the guide tube and the shell.

[0018] Preferably, the step 2 comprises:

[0019] The multiphase flow column is placed in a guide tube, and the multiphase flow column is accelerated or decelerated in the guide tube, and the multiphase flow quasi-dynamic phantom is scanned multiple times by using a CT device to be tested to obtain original dynamic measurement data;

[0020] Data of multiple target rounds are extracted from the original dynamic measurement data, wherein each target round corresponds to a different speed of the multiphase flow field column, and the extracted data are CT reconstructed and binarized to obtain dynamic measurement data of the multiphase flow quasi-dynamic phantom at multiple different speeds.

[0021] Preferably, the true value data is calculated according to the first static three-dimensional structure data and the second static three-dimensional structure data according to the following steps:

[0022] Selecting a time T in the target round as the time for calculating the structural similarity index;

[0023] Determine the relative position relationship between the multiphase flow field column, the guide tube and the housing at the time T according to the original dynamic measurement data;

[0024] According to the relative position relationship, the first static three-dimensional structure data and the second static three-dimensional structure data are spliced ​​to obtain true value data at a speed corresponding to the target round.

[0025] Preferably, the calculation formula of the structural similarity index SSIM is:

[0026]

[0027] Among them, μ x ,μ y Respectively represent the average values ​​of true value data and dynamic measurement data; σ x ,σ y ,σ xy They represent the standard deviation of the true value data and the dynamic measurement data and their covariance respectively; C 1 ,C 2 is a constant.

[0028] Preferably, the CT equipment testing method further comprises:

[0029] The maximum credible test speed of the CT device to be tested is determined according to a threshold value of the structural similarity index.

[0030] The embodiment of the present invention further provides a CT equipment testing method, using the multiphase flow quasi-dynamic phantom, comprising:

[0031] Step 1: Use a reference CT device to scan the multiphase flow field column, the guide tube and the shell to obtain first static three-dimensional structure data of the multiphase flow field column and second static three-dimensional structure data of the guide tube and the shell;

[0032] Step 2: the multiphase flow column is moved in the guide tube at a predetermined speed, and the multiphase flow quasi-dynamic phantom is scanned by using the CT device to be tested to obtain dynamic measurement data of the multiphase flow quasi-dynamic phantom at the predetermined speed;

[0033] Step 3: Calculate the true value data at the predetermined speed according to the first static three-dimensional structure data and the second static three-dimensional structure data, and calculate the structural similarity index at the predetermined speed based on the true value data and the dynamic measurement data;

[0034] Step 4: Repeat steps 2 and 3 to make the multiphase flow field column move in the guide tube at different predetermined speeds, and obtain a structural similarity index corresponding to each predetermined speed.

[0035] The beneficial effects of the present invention are:

[0036] 1. The multiphase flow quasi-dynamic phantom uses the movement of the multiphase flow field column in the guide tube to simulate the multiphase flow. It can simulate most of the motion characteristics in the real multiphase flow field, thereby realizing the test of the CT equipment used for multiphase flow measurement.

[0037] 2. The CT equipment testing method utilizes a multiphase flow quasi-dynamic phantom and can use existing measurement methods to obtain true value data and dynamic measurement data of the multiphase flow field, thereby realizing the testing of the CT equipment.

[0038] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0040] Figure 1 A schematic structural diagram of a multiphase flow quasi-dynamic phantom for CT equipment testing according to an exemplary embodiment of the present invention is shown.

[0041] Figure 2 A schematic structural diagram of a multiphase flow field column of a multiphase flow quasi-dynamic phantom for CT equipment testing according to an exemplary embodiment of the present invention is shown.

[0042] Figure 3A schematic structural diagram of a shell of a multiphase flow quasi-dynamic phantom for CT equipment testing according to an exemplary embodiment of the present invention is shown.

[0043] Figure 4 A schematic structural diagram of a multiphase flow quasi-dynamic phantom for CT equipment testing according to an exemplary embodiment of the present invention is shown.

[0044] Description of reference numerals:

[0045] 1. Driving mechanism; 2. Guide tube; 3. Shell; 4. Multiphase flow field column; 5. Bubble. DETAILED DESCRIPTION

[0046] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0047] The embodiment of the present invention provides a multiphase flow quasi-dynamic phantom for CT equipment testing, comprising a housing, a guide tube, and a multiphase flow field column;

[0048] The guide tube is arranged in the shell, the multiphase flow field column is a solid structure, at least one bubble is distributed inside, the multiphase flow field column is detachably arranged in the guide tube, and can move along the axial direction of the guide tube.

[0049] The multiphase flow quasi-dynamic phantom utilizes the movement of the multiphase flow field column in the guide tube to simulate the multiphase flow, and can simulate most of the motion characteristics in the real multiphase flow field, thereby realizing the testing of the CT equipment used for multiphase flow measurement.

[0050] Further, the housing, the multiphase flow field column and the guide tube are all made of materials that allow X-rays to penetrate, preferably made of polymer materials that allow X-rays to penetrate, and more preferably made of low-density polymer materials that allow X-rays to penetrate. For example, the housing, the multiphase flow field column and the guide tube are all made of transparent acrylic materials. According to actual needs, bubbles with a shape, size, and distribution similar to the actual multiphase flow field are formed inside the multiphase flow field column to simulate the actual flow field.

[0051] Furthermore, the multiphase flow column is cylindrical, the guide tube is a round tube, and the inner diameter of the guide tube is adapted to the outer diameter of the multiphase flow column, so that the multiphase flow column can move smoothly in the guide tube along the axial direction of the guide tube without deflection. Generally speaking, the movement speed of the fluid in the multiphase flow field is mainly along the vertical direction, and there is a smaller component in the horizontal direction. Therefore, the axial direction of the guide tube is arranged along the vertical direction, or forms an angle with the vertical direction, and the angle is preferably less than or equal to 15°.

[0052] Furthermore, the housing is used to simulate the reactor structure at the multiphase flow field, and is used to support and fix the guide tube to keep the guide tube stable. In addition, the housing can be designed as a quick-disassembly structure to facilitate the individual measurement of the multiphase flow field column.

[0053] Furthermore, the multiphase flow quasi-dynamic phantom also includes a driving mechanism, and the multiphase flow field column is connected to the driving mechanism, and can move in the guide tube along the axial direction of the guide tube under the action of the driving mechanism. The movement speed of the multiphase flow field column can be conveniently controlled by the driving mechanism to simulate the movement speed of different phase structures in the multiphase flow field. The driving mechanism, for example, includes a motor and a necessary transmission mechanism, and the transmission mechanism is used to convert the rotation of the motor into the linear motion of the multiphase flow field column.

[0054] Furthermore, a guide tube and a multiphase flow field column form a phantom unit, and the multiphase flow quasi-dynamic phantom may include a plurality of phantom units, and the plurality of phantom units are substantially evenly distributed in the housing. When the multiphase flow quasi-dynamic phantom includes a plurality of phantom units, a complex multiphase flow field can be simulated. In this case, if a driving mechanism is used to drive the multiphase flow field columns of each phantom unit, the same driving mechanism is used to drive each multiphase flow field column to ensure the relative motion characteristics of each multiphase flow field column.

[0055] The embodiment of the present invention further provides a CT equipment testing method, using the multiphase flow quasi-dynamic phantom, comprising:

[0056] Step 1: Use a reference CT device to scan the multiphase flow field column, the guide tube and the shell to obtain the first static three-dimensional structure data of the multiphase flow field column and the second static three-dimensional structure data of the guide tube and the shell.

[0057] In step 1, the reference CT device refers to a CT device that has been tested or calibrated to meet the measurement requirements. By scanning the multiphase flow column separately using the reference CT device, voxel format data of the multiphase flow column under static conditions can be obtained, and each voxel stores a floating point number, representing the density measurement value corresponding to the voxel. Since bubbles and their surrounding entities have different densities, the voxel format data can represent the three-dimensional spatial distribution of bubbles under static conditions.

[0058] Similarly, the guide tube and the shell are scanned as a whole using a reference CT device to obtain voxel format data of the guide tube and the shell under static conditions. Similarly, each voxel stores a floating point number, representing the density measurement value corresponding to the voxel.

[0059] Preferably, the voxel format data is binarized to obtain the first static three-dimensional structure data of the multiphase flow column and the second static three-dimensional structure data of the guide tube and the shell. After the binarization, the value 1 in the voxel format data represents a bubble, and the value 0 represents a non-bubble.

[0060] Step 2: Make the multiphase flow field column accelerate or decelerate in the guide tube, and use the CT device to be tested to scan the multiphase flow quasi-dynamic phantom to obtain dynamic measurement data of the multiphase flow quasi-dynamic phantom at multiple different speeds.

[0061] Specifically, the multiphase flow field column is placed in a guide tube, and the multiphase flow field column is accelerated or decelerated in the guide tube. At the same time, the multiphase flow quasi-dynamic phantom is scanned multiple times using the CT device to be tested to obtain original dynamic measurement data.

[0062] Data of multiple target rounds are extracted from the original dynamic measurement data, wherein each target round corresponds to a different speed of the multiphase flow field column. The target round data extracted from the original dynamic measurement data includes the radiation dose distribution received by the X-ray detector each time the CT device is exposed at different focal points. After being processed by the CT reconstruction algorithm, reconstructed three-dimensional structural data can be obtained. Obtaining three-dimensional structural data by reconstruction is a prior art in the field and will not be described in detail here. Since the multiphase flow field column is in motion, the motion state inside the multiphase flow field column is different when different focal points are exposed, which will introduce artifacts in the reconstructed data.

[0063] The original dynamic measurement data is also voxel format data, and each voxel stores a floating point number, which represents the density measurement value corresponding to the voxel. The data of multiple target rounds extracted are binarized to obtain the dynamic measurement data of the multiphase flow quasi-dynamic phantom at various speeds. Similarly, after binarization, the value 1 in the voxel format data represents bubbles, and the value 0 represents non-bubbles.

[0064] Step 3: Calculate the true value data at each speed according to the first static three-dimensional structure data and the second static three-dimensional structure data, and calculate the structural similarity index corresponding to each speed based on the true value data and the dynamic measurement data.

[0065] Specifically, according to the following steps, the true value data is calculated according to the first static three-dimensional structure data and the second static three-dimensional structure data:

[0066] Select time T in the target round as the time to calculate the structural similarity index;

[0067] According to the original dynamic measurement data, the relative position relationship between the multiphase flow field column, the guide tube and the housing at time T is determined;

[0068] According to the relative position relationship, the first static three-dimensional structure data and the second static three-dimensional structure data are spliced ​​to obtain true value data at a speed corresponding to the target round.

[0069] Each round of scanning lasts for a very short period of time (about a few milliseconds to tens of milliseconds). In this period of time, a time T is selected to determine the relative position relationship between the multiphase flow field column, the guide tube and the housing at the time T according to the original dynamic measurement data, so as to splice the first static three-dimensional structure data and the second static three-dimensional structure data to obtain the true value data at the speed corresponding to the target round. The method of data splicing is the prior art in the field and will not be described in detail here.

[0070] Then, the structural similarity index SSIM is used as an evaluation index to evaluate the performance of the CT equipment. The calculation formula of SSIM is:

[0071]

[0072] Among them, μ x ,μ y Respectively represent the average values ​​of true value data and dynamic measurement data; σ x ,σ y ,σ xy Respectively represent the standard deviation of the true value data and the dynamic measurement data and their covariance; V 1 ,C 2 is a constant. Both the true value data and the dynamic measurement data are voxel format data, the average value refers to the average value of the data corresponding to each voxel in the voxel format data, and the standard deviation refers to the standard deviation of the data corresponding to each voxel in the voxel format data.

[0073] Furthermore, the CT device testing method further includes: determining a maximum credible test speed of the CT device to be tested according to a threshold value of the structural similarity index.

[0074] In step 3, the structural similarity index corresponding to each speed is calculated, and the threshold of the structural similarity index is compared with the structural similarity index at different speeds. When the structural similarity index at a certain speed is greater than the threshold of the structural similarity index, it indicates that the CT device to be tested meets the dynamic measurement requirements of the multiphase flow system. By comparing the structural similarity index at different speeds with the threshold of the structural similarity index, the maximum credible test speed of the CT device to be tested can be determined, which indicates the maximum speed at which the test result is credible (i.e., meets a certain accuracy).

[0075] In another embodiment, the present invention provides a CT equipment testing method, using the multiphase flow quasi-dynamic phantom, comprising:

[0076] Step 1: Scanning the multiphase flow column, the guide tube and the shell using a reference CT device to obtain first static three-dimensional structure data of the multiphase flow column and second static three-dimensional structure data of the guide tube and the shell;

[0077] Step 2: The multiphase flow field column is moved in the guide tube at a predetermined speed, and the multiphase flow quasi-dynamic phantom is scanned by using the CT device to be tested to obtain dynamic measurement data of the multiphase flow quasi-dynamic phantom at the predetermined speed;

[0078] Step 3: Calculate the true value data at a predetermined speed according to the first static three-dimensional structure data and the second static three-dimensional structure data, and calculate the structural similarity index at the predetermined speed based on the true value data and the dynamic measurement data;

[0079] Step 4: Repeat steps 2 and 3 to make the multiphase flow column move in the guide tube at different predetermined speeds, and obtain the structural similarity index corresponding to each predetermined speed.

[0080] The difference between this embodiment and the previous embodiment is that in step 2, the multiphase flow field column moves in the guide tube at a constant predetermined speed. In this case, it is necessary to repeat steps 2 and 3 multiple times to obtain the structural similarity index at different predetermined speeds. Other details of this embodiment are similar to those of the previous embodiment and will not be repeated here.

[0081] Specifically, the multiphase flow field column can be driven by a motor to move in the guide tube at a constant predetermined speed.

[0082] Example 1

[0083] Figure 1 A schematic diagram of the structure of a multiphase flow quasi-dynamic phantom for CT equipment testing according to an exemplary embodiment of the present invention is shown. Figure 2 A schematic diagram of the structure of a multiphase flow field column of a multiphase flow quasi-dynamic phantom for CT equipment testing according to an exemplary embodiment of the present invention is shown. Figure 3 A schematic structural diagram of a shell of a multiphase flow quasi-dynamic phantom for CT equipment testing according to an exemplary embodiment of the present invention is shown.

[0084] like Figure 1-3 As shown, this embodiment provides a multiphase flow quasi-dynamic phantom for CT equipment testing, including a driving mechanism 1, a housing 3, a guide tube 2, and a multiphase flow field column 4;

[0085] The guide tube 2 is arranged in the outer shell 3 . The multiphase flow field column 4 is a solid structure with a plurality of bubbles 5 distributed inside. The multiphase flow field column 4 is detachably arranged in the guide tube 2 and can move along the axial direction of the guide tube 2 .

[0086] The housing, multiphase flow column and guide tube are all made of acrylic material. The housing 3 is a cylinder with a diameter of 200 mm, including an upper and lower part, to facilitate the fixing of the guide tube 2. The multiphase flow column 4 is cylindrical, and the guide tube 2 is a round tube. The inner diameter of the guide tube 2 is adapted to the outer diameter of the multiphase flow column 4, so that the multiphase flow column can move in the guide tube along the axial direction of the guide tube without deflection. The axial direction of the guide tube 2 is arranged in the vertical direction.

[0087] In this embodiment, the driving mechanism 1 is a release-free fall mechanism, including a pin and a connecting line connected to the pin. The other end of the connecting line is connected to the multiphase flow field column 4. When the driving mechanism receives a control signal, the pin is retracted, and the multiphase flow field column 4 falls freely along the guide tube 2. By changing the initial height of the multiphase flow field column 4, the movement speed of the multiphase flow field column 4 can be changed. Compared with motor drive, this structure has lower cost and better anti-electromagnetic interference performance.

[0088] The CT equipment testing method of this embodiment includes:

[0089] Step 1: Use a reference CT device to scan the multiphase flow field column 4, and scan the guide tube 2 and the shell 3 to obtain the first static three-dimensional structure data of the multiphase flow field column 4, and the second static three-dimensional structure data of the guide tube 2 and the shell 3.

[0090] Step 2: Send a control signal to activate the driving mechanism, and the multiphase flow field column 4 performs free fall movement in the guide tube 2. At the same time, the multiphase flow quasi-dynamic phantom is scanned using the CT device to be tested to obtain dynamic measurement data of the multiphase flow quasi-dynamic phantom at multiple different speeds.

[0091] Step 3: According to the first static three-dimensional structure data and the second static three-dimensional structure data, the true value data at each speed is calculated respectively, and based on the true value data and the dynamic measurement data, the structural similarity index corresponding to each speed is calculated. The calculation results are shown in the following table:

[0092] Movement speed (m / s) 0.2 0.4 0.6 0.8 1.0 1.2 SSIM 0.9847 0.9805 0.9741 0.9645 0.8914 0.8352

[0093] Taking the threshold of the structural similarity index as 0.90, it can be determined that when the movement speed of the multiphase flow field column is lower than 0.8 m / s, the CT device can meet the dynamic measurement requirements of the multiphase flow system. This movement speed can be determined as the maximum credible test speed of the CT device to be tested.

[0094] Example 2

[0095] Figure 4The schematic diagram of the structure of a multiphase flow quasi-dynamic phantom for CT equipment testing according to an exemplary embodiment of the present invention is shown. The difference from Example 1 is that a guide tube 2 and a multiphase flow field column 4 form a phantom unit, and the multiphase flow quasi-dynamic phantom includes four phantom units, and the four phantom units are basically evenly distributed in the shell 3 along the circumferential direction. Among them, two guide tubes 2 are arranged in the vertical direction, and the two guide tubes 2 form an angle of 5° with the vertical direction. This multiphase flow quasi-dynamic phantom can simulate a multiphase flow with a certain horizontal motion component.

[0096] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A multiphase flow quasi-dynamic phantom for CT equipment testing, characterized in that: It includes a shell, a guide tube, and a multiphase flow field column; The guide tube is arranged in the shell, the multiphase flow field column is a solid structure with at least one bubble distributed inside, and the multiphase flow field column is detachably arranged in the guide tube and can move along the axial direction of the guide tube.

2. The multiphase flow quasi-dynamic phantom according to claim 1, characterized in that: The housing, the multiphase flow field column and the guide tube are all made of a polymer material that allows X-rays to penetrate; and / or The multiphase flow field column is cylindrical, the guide tube is a round tube, and the inner diameter of the guide tube is adapted to the outer diameter of the multiphase flow field column.

3. The multiphase flow quasi-dynamic phantom according to claim 1, characterized in that: The axial direction of the guide tube is arranged along the vertical direction or forms an angle with the vertical direction, and the angle is less than or equal to 15°; and / or The multiphase flow quasi-dynamic phantom further comprises a driving mechanism, and the multiphase flow field column is connected to the driving mechanism and can move in the guide tube along the axial direction of the guide tube under the action of the driving mechanism.

4. The multiphase flow quasi-dynamic phantom according to claim 1, characterized in that: One of the guide tubes and one of the multiphase flow field columns forms a phantom unit. The multiphase flow quasi-dynamic phantom includes a plurality of phantom units, and the plurality of phantom units are substantially evenly distributed in the shell.

5. A CT equipment testing method, using the multiphase flow quasi-dynamic phantom according to any one of claims 1 to 3, characterized in that: include: Step 1: Use a reference CT device to scan the multiphase flow field column, the guide tube and the shell to obtain first static three-dimensional structure data of the multiphase flow field column and second static three-dimensional structure data of the guide tube and the shell; Step 2: causing the multiphase flow field column to perform acceleration or deceleration movement in the guide tube, and using the CT device to be tested to scan the multiphase flow quasi-dynamic phantom to obtain dynamic measurement data of the multiphase flow quasi-dynamic phantom at multiple different speeds; Step 3: Calculate the true value data at each speed according to the first static three-dimensional structure data and the second static three-dimensional structure data, and calculate the structural similarity index corresponding to each speed based on the true value data and the dynamic measurement data.

6. The CT equipment testing method according to claim 5, characterized in that: The step 1 comprises: Scanning the multiphase flow column using a reference CT device to obtain voxel format data of the multiphase flow column under a static state, and scanning the guide tube and the shell using a reference CT device to obtain voxel format data of the guide tube and the shell, wherein each voxel stores a floating point number, and the floating point number represents a density measurement value corresponding to the voxel; The voxel format data of the multiphase flow column is binarized to obtain the first static three-dimensional structure data of the multiphase flow column, and the voxel format data of the guide tube and the shell are binarized to obtain the second static three-dimensional structure data of the guide tube and the shell.

7. The CT equipment testing method according to claim 5, characterized in that: The step 2 comprises: The multiphase flow column is placed in a guide tube, and the multiphase flow column is accelerated or decelerated in the guide tube, and the multiphase flow quasi-dynamic phantom is scanned multiple times by using a CT device to be tested to obtain original dynamic measurement data; Data of multiple target rounds are extracted from the original dynamic measurement data, wherein each target round corresponds to a different speed of the multiphase flow field column, and the extracted data are CT reconstructed and binarized to obtain dynamic measurement data of the multiphase flow quasi-dynamic phantom at multiple different speeds.

8. The CT equipment testing method according to claim 7, characterized in that: According to the following steps, true value data is calculated according to the first static three-dimensional structure data and the second static three-dimensional structure data: Selecting a time T in the target round as the time for calculating the structural similarity index; Determine the relative position relationship between the multiphase flow field column, the guide tube and the housing at the time T according to the original dynamic measurement data; According to the relative position relationship, the first static three-dimensional structure data and the second static three-dimensional structure data are spliced ​​to obtain true value data at a speed corresponding to the target round.

9. The CT equipment testing method according to claim 5, characterized in that: The calculation formula of the structural similarity index SSIM is: Among them, μ x ,μ y Respectively represent the average values ​​of true value data and dynamic measurement data; σ x ,σ y ,σ xt They represent the standard deviation of the true value data and the dynamic measurement data and their covariance respectively; C1 and C2 are constants.

10. The CT equipment testing method according to claim 5, characterized in that: Also includes: The maximum credible test speed of the CT device to be tested is determined according to a threshold value of the structural similarity index.

11. A CT equipment testing method, using the multiphase flow quasi-dynamic phantom according to any one of claims 1 to 3, characterized in that: include: Step 1: Use a reference CT device to scan the multiphase flow field column, the guide tube and the shell to obtain first static three-dimensional structure data of the multiphase flow field column and second static three-dimensional structure data of the guide tube and the shell; Step 2: the multiphase flow column is moved in the guide tube at a predetermined speed, and the multiphase flow quasi-dynamic phantom is scanned by using the CT device to be tested to obtain dynamic measurement data of the multiphase flow quasi-dynamic phantom at the predetermined speed; Step 3: Calculate the true value data at the predetermined speed according to the first static three-dimensional structure data and the second static three-dimensional structure data, and calculate the structural similarity index at the predetermined speed based on the true value data and the dynamic measurement data; Step 4: Repeat steps 2 and 3 to make the multiphase flow field column move in the guide tube at different predetermined speeds, and obtain the structural similarity index corresponding to each predetermined speed.

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