Reference phantom and evaluation method, magnetic resonance imaging system

Abstract

The present disclosure provides a reference phantom and an evaluation method, and a magnetic resonance imaging system, the reference phantom is used as a reference to obtain the centering accuracy of a bed and a magnetic resonance scanning device in a detection surface in a magnetic resonance imaging system, the reference phantom comprises: a box body having a first end face; a centering mark located at the first end face; and a reference cylinder located in the box body, an axis of the reference cylinder coincides with a center of the centering mark, so that the reference phantom can better provide a reference for obtaining the centering accuracy of the bed and the magnetic resonance scanning device in the detection surface in the magnetic resonance imaging system.

Description

Technical Field

[0001] This disclosure relates to the field of magnetic resonance imaging technology, and in particular to a reference phantom and evaluation method, and a magnetic resonance imaging system. Background Technology

[0002] Magnetic resonance imaging (MRI) has become a common imaging technique. As a novel imaging technology, MRI does not pose a threat to human health. Small animal MRI is a high-tech field with wide applications in interdisciplinary areas such as materials science and basic biomedical research. It holds great promise in both basic biomedical research and disease-related applications. Biomedical research using animal models avoids the risks associated with human experiments, overcomes the drawbacks of long incubation periods and disease courses in some diseases, and allows for strict control of animal experimental conditions, reducing the influence of individual differences. Imaging techniques, especially MRI, are currently an indispensable tool in animal model research.

[0003] For animal magnetic resonance imaging (MRI), ultra-high field (e.g., 9.4T) MRI systems are generally used. These systems include a movable bed, typically a cantilever design, that can extend and retract into the scanning cavity of the MRI system. To obtain accurate MRI images, isocentric scanning is performed, which places high demands on the positioning of the bed within the scanning cavity. The reference point must be precisely located at the center of the field of view (FOV) of the MRI scanner. Therefore, it is necessary to evaluate the accuracy of the bed's entry position into the scanning cavity. Summary of the Invention

[0004] In view of this, it is necessary to provide a reference phantom to evaluate or correct the accuracy of the position of the bed of a magnetic resonance imaging system entering the scanning cavity.

[0005] This disclosure provides a reference phantom for use as a reference to obtain the alignment accuracy between the bed in a magnetic resonance imaging system and the magnetic resonance scanning device. The reference phantom includes: a box having a first end face; an alignment mark located on the first end face; and a reference cylinder located inside the box, the axis of the reference cylinder coinciding with the center of the alignment mark.

[0006] With this setup, the structure of the reference phantom is relatively simple. The reference cylinder is used to enable the magnetic resonance scanning equipment to obtain patterns. The shape of the cylinder provides continuous and controllable changes, which is suitable for providing patterns for images at various positions. By setting the axis of the reference cylinder to be located at the centering mark, even if the reference phantom is rotated by an unknown angle along the axis during placement, the relative position of the reference cylinder and the centering mark in the vertical plane of the axis will not change. This makes the reference phantom less restrictive when used as a reference for the mating device. The reference phantom can provide a better reference for obtaining the centering accuracy of the bed and the magnetic resonance scanning equipment in the detection plane in the magnetic resonance imaging system.

[0007] In some implementations, the chamber is filled with a medium that is used to obtain different signals from the reference cylinder by a magnetic resonance scanning device.

[0008] With this setup, the signal difference between the medium and the reference cylinder can be used to make the images obtained by the magnetic resonance scanning device have distinguishable patterns, thereby making the patterns of the corresponding reference cylinder easier or more accurate to identify.

[0009] For example, the medium includes water.

[0010] Water has the molecular formula H2O. Due to its long lateral relaxation time, water is beneficial for enhancing the signal difference between the medium and the reference cylinder.

[0011] In some embodiments, the reference cylinder is filled with a medium, and the reference mold also includes a reference column located inside the reference cylinder and coaxial with the reference cylinder.

[0012] With this setup, the reference column helps to quickly determine the centering accuracy of the image obtained from the magnet.

[0013] In some implementations, the radius of the reference post is matched to the value of the minimum centering accuracy requirement.

[0014] To ensure optimal operation of a magnetic resonance imaging (MRI) system, the centering accuracy is expected to be within a certain range, for example, not exceeding a minimum requirement, and ideally approaching zero. When the image acquired by the magnet includes a pattern of a reference pillar, it can be preliminarily determined that the centering accuracy will not be larger than the radius of the reference pillar.

[0015] For example, the diameter of the reference post is 1 mm.

[0016] With this setting, if the image obtained by the magnet includes the pattern of the reference pillar, it can be preliminarily determined that the center accuracy is 1mm; if the image obtained by the magnet does not include the pattern of the reference pillar, it can be preliminarily determined that the center accuracy does not meet the setting of less than 1mm.

[0017] In some implementations, the box is a cube.

[0018] This design makes it easier to place the box inside the bed.

[0019] For example, the wall of the reference cylinder may be hollow, or the housing may include an annular groove filled with water to form the reference cylinder. The reference cylinder in this embodiment is made of water, which can increase the signal strength obtained by the magnetic resonance imaging (MRI) scanner.

[0020] A second aspect of this disclosure provides an evaluation method for obtaining the alignment accuracy of a bed and a magnetic resonance scanning device in a detection plane within a magnetic resonance imaging system. The evaluation method includes: placing the aforementioned reference phantom on the bed and positioning the alignment mark of the reference phantom at a reference point on the bed; moving the bed from outside the scanning cavity of the magnetic resonance scanning device to inside the scanning cavity of the magnetic resonance scanning device to achieve a second state for the bed; obtaining a first image of the reference phantom in a first plane parallel to the axis of a reference cylinder using the magnetic resonance scanning device, wherein the first image includes a first pattern and a second pattern corresponding to the cylinder wall of the reference cylinder; and determining a first position of the center of the magnetic resonance scanning device relative to the alignment mark along the perpendicular direction of the first plane based on the first pattern and the second pattern.

[0021] In order to obtain the relative position of the magnetic resonance scanning device and the bed, this evaluation method aligns the centering mark with the reference point of the bed, and then obtains the first image of the reference phantom through the magnetic resonance scanning device when the bed is in the second state. Then, the position of the field of view center of the magnetic resonance scanning device relative to the reference cylinder can be determined. Since the centering mark of the reference phantom is aligned with the reference cylinder, the deviation between the field of view center of the magnetic resonance scanning device and the reference point of the bed in the detection plane can be evaluated more accurately, and the centering accuracy between the bed and the magnetic resonance scanning device can be obtained.

[0022] In some embodiments, the evaluation method further includes: obtaining a second image of the reference phantom in a second plane parallel to the axis of the reference cylinder and perpendicular to the first plane using a magnetic resonance scanning device, wherein the second image includes a third pattern and a fourth pattern corresponding to the cylinder wall of the reference cylinder; determining a second position of the field of view center of the magnetic resonance scanning device relative to the centering mark along the perpendicular direction of the second plane based on the third pattern and the fourth pattern; and determining the centering accuracy of the bed and the magnetic resonance scanning device in the detection plane based on the first position and the second position.

[0023] With this setup, the alignment accuracy between the bed and the magnetic resonance scanning equipment can be evaluated in two directions on the detection surface by placing the phantom once. Furthermore, due to the rotational symmetry of the reference cylinder, the evaluation steps in both directions are similar, making the evaluation method simpler and faster.

[0024] In some implementations, the first image includes a fifth pattern corresponding to a reference post; and the alignment accuracy is determined based on the values ​​of the radius of the fifth pattern and the reference post.

[0025] With this setup, an approximate alignment accuracy can be obtained very quickly using this evaluation method, and then it can be determined whether to further evaluate the alignment accuracy between the bed and the magnetic resonance scanning equipment in more detail as needed.

[0026] In some embodiments, the step of positioning the centering mark of the reference phantom at the reference point of the bed includes: illuminating the reference point of the bed with a laser lamp of the magnetic resonance imaging system, wherein the axial direction of the reference cylinder of the reference phantom is perpendicular to the detection surface and the centering mark is illuminated by the laser lamp.

[0027] This setting allows for quicker and more accurate alignment of the center markers.

[0028] This disclosure provides a magnetic resonance imaging system, comprising: a magnetic resonance scanning device having a scanning cavity; a bed movable relative to the magnetic resonance scanning device along a first axis within a detection plane, having a first state located outside the scanning cavity of the magnetic resonance scanning device and a second state located within the scanning cavity of the magnetic resonance scanning device; and the aforementioned reference phantom for use as a reference to obtain the alignment accuracy between the bed and the magnetic resonance scanning device within the detection plane.

[0029] This magnetic resonance imaging system can assess the alignment accuracy between the bed and the magnetic resonance scanning equipment using a reference phantom during routine use. The system is reliable and produces good imaging results.

[0030] In some embodiments, the magnetic resonance imaging system further includes a laser lamp located outside the scanning cavity of the magnetic resonance scanning device for illuminating a reference point on the bed.

[0031] By setting up laser lights, the reference points of the bed can be located more directly and accurately.

[0032] For example, the magnetic resonance imaging system further includes: a memory for storing a computer program product; and a processor communicatively connected to the memory to execute the computer program product and implement the aforementioned evaluation method.

[0033] The fourth aspect of this disclosure provides a computer program product, including a computer program that, when executed by a processor, implements the aforementioned evaluation method.

[0034] The fifth aspect of this disclosure provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the aforementioned evaluation method.

[0035] The computer equipment, computer program product, and computer-readable storage medium provided in this disclosure are used to implement the aforementioned evaluation method. By determining the positions of the bed and the magnetic resonance scanning device relative to the reference phantom, and combining the determined positional relationship between the reference cylinder and the centering mark in the reference phantom, the centering accuracy of the bed and the magnetic resonance scanning device in the detection plane in the magnetic resonance imaging system is obtained. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of the reference phantom in an embodiment of this disclosure;

[0037] Figure 2 for Figure 1 A schematic top view of the central reference phantom;

[0038] Figure 3 for Figure 2 A cross-sectional view of the central reference phantom;

[0039] Figure 4 for Figure 1 A schematic front view of the central reference phantom;

[0040] Figure 5 This is a schematic diagram illustrating the deviation of the magnet center in an embodiment of this disclosure;

[0041] Figure 6 A schematic flowchart illustrating an evaluation method provided in an embodiment of this disclosure;

[0042] Figure 7 for Figure 5 A schematic diagram of the first image obtained from the magnet;

[0043] Figure 8 This is a schematic diagram of another first image obtained by the magnet in an embodiment of this disclosure;

[0044] Figure 9 This is a schematic diagram illustrating another type of magnet center deviation in an embodiment of this disclosure;

[0045] Figure 10 A schematic flowchart illustrating another evaluation method provided in an embodiment of this disclosure;

[0046] Figure 11 for Figure 9 A schematic diagram of the first image obtained from the magnet;

[0047] Figure 12 for Figure 9 A schematic diagram of the second image obtained by the magnet;

[0048] Figure 13 This is a schematic diagram of the structure of a magnetic resonance imaging system provided in an embodiment of the present disclosure;

[0049] Figure 14 This is a schematic diagram of the magnetic resonance imaging system provided in an embodiment of the present disclosure in another state.

[0050] Reference numerals: 1. Base model; 101. First cross-section; 102. Second cross-section; 2. Box body; 21. First box body pattern; 22. Second box body pattern; 23. Third box body pattern; 3. Base cylinder; 31. First section; 32. Second section; 310. First pattern; 311. First tangent; 320. Second pattern; 321. Second tangent; 330. Third pattern; 331. Third tangent; 340. Fourth pattern; 341. Fourth tangent; 4. 40. Centering mark; 5. Marking pattern; 61. Reference column; 70. Fifth pattern; 61. Sixth pattern; 61. First image; 610. First image field of view; 62. Second image; 620. Second image field of view; 7. Magnetic resonance imaging system; 701. Bus; 702. Processor; 703. Memory; 704. Input / output device; 8. Compound motion bed; 81. Base; 82. Bed body; 9. Laser lamp; 10. Magnetic resonance scanning equipment; 110. Scanning cavity. Detailed Implementation

[0051] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this disclosure.

[0052] It should be noted that when a component is said to be "installed on" another component, it can be directly on the other component or it may be in a component that is centered on it. When a component is said to be "set on" another component, it can be directly set on the other component or it may also be in a component that is centered on it. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or it may also be in a component that is centered on it.

[0053] The structural dimensions shown in the accompanying drawings in this article do not represent actual dimensions and may be adjusted as needed during actual production. The directional terms "up," "down," "left," and "right" used in this article refer to the orientation shown in the drawings and should not be considered as limitations on the actual use of the product unless explicitly stated otherwise.

[0054] The terms "first," "second," "third," etc., used in this article are only used to distinguish the same features. Understandably, the first pattern in this article can also be called the second pattern, and the second pattern can also be called the first pattern.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0056] like Figure 1 As shown, this disclosure provides a reference phantom 1. This reference phantom 1 can be used as follows: Figure 13 The magnetic resonance imaging system 7 shown. The reference phantom 1 includes a housing 2, a reference cylinder 3, and at least one centering mark 4. The reference cylinder 3 is located inside the housing 2.

[0057] Figure 1 The X, Y, and Z axes are perpendicular to each other. The direction parallel to the Y-axis can be considered the primary direction. (Reference) Figure 1 and Figure 2 The housing 2 includes two end faces opposite each other along the Y-axis, for example, the top surface is the first end face and the bottom surface is the second end face. A centering mark 4 may be located on the first end face; exemplarily, another centering mark 4 is located on the second end face. Exemplarily, the centering mark 4 can be visually identifiable, may have a raised or recessed shape, or may be a dyed layer of a different color than the rest of the end face. The end face of the housing 2 opposite to the centering mark 4 may include a support surface parallel to the XZ plane, for example, the end face is a plane perpendicular to the Y-axis. The centering mark 4 may have a center. In some embodiments, the centering mark 4 is a cross structure, and the center of the centering mark 4 is the center of the cross structure, i.e., the intersection point of the two arms of the cross structure. The centering mark 4 can be used to determine the central axis represented by the centering mark 4.

[0058] The reference cylinder 3 is fixedly connected to the housing 2. Specifically, the reference cylinder 3 and the centering mark 4 have a fixed positional relationship. The axis of the reference cylinder 3 can be set along the Y-axis direction. For example, the axis of the reference cylinder 3 coincides with the center of the centering mark 4. In a plane parallel to the X and Z axes, the axis of the reference cylinder 3 coincides with the center projection of the centering mark 4, that is, the axis of the reference cylinder 3 coincides with the central axis represented by the centering mark 4. The reference cylinder 3 can acquire image information from the magnetic resonance scanning device 10.

[0059] refer to Figure 13 and Figure 14The magnetic resonance imaging system 7 includes a compound motion bed 8, a laser lamp 9, and a magnetic resonance scanning device 10. Exemplarily, the magnetic resonance scanning device 10 has a scanning cavity 110. In other embodiments, the magnetic resonance scanning device has an open structure, in which case its scanning area or scanning space can still be referred to as the scanning cavity. The base 81 of the compound motion bed 8 can carry the bed body 82 up and down in, for example, a vertical direction. The position of the bed body 82 in the up and down direction can be determined by the base 81 or other means. The surface perpendicular to this up and down direction can be considered as the detection surface of the magnetic resonance imaging system 7. It should be understood that this detection surface is not a surface that limits the imaging function of the magnetic resonance imaging system 7, but rather a name for certain surfaces when evaluating using the reference phantom 1. The bed body 82 is movable relative to the magnetic resonance scanning device 10, for example, entering and exiting the scanning cavity 110 of the magnetic resonance scanning device 10 along a first axial direction (Z-axis direction) parallel to the detection surface. Subsequently, the bed body 82 may have a first state located outside the scanning cavity 110 of the magnetic resonance scanning device 10 (see reference). Figure 13 ) and the second state located within the scanning cavity 110 of the magnetic resonance scanning device 10 (reference) Figure 14 For example, in the first state, the laser lamp 9 can illuminate the reference point of the bed 82; the second state can refer to the state of the bed 82 after the magnetic resonance imaging system 7 executes the command "one-click enter the center of the magnet"; after executing the command "one-click enter the center of the magnet", the bed 82 will directly enter the scanning cavity and reach the calibration position, and the reference point of the bed 82 should theoretically reach the center of the field of view S of the magnetic resonance scanning device 10.

[0060] In any detection plane, under ideal second conditions, the reference point of the bed 82 coincides with the field of view center S of the magnetic resonance scanning device 10. During the actual movement of the bed 82, the reference point of the bed 82 and the field of view center S of the magnetic resonance scanning device 10 may deviate within the detection plane, that is, there may be deviations in the Z-axis direction and / or X-axis direction.

[0061] The reference phantom provided in this embodiment is used as a reference to obtain the alignment accuracy between the bed and the magnetic resonance scanning device in the detection plane of the magnetic resonance imaging system. Specifically, the alignment mark is used to align the reference phantom with the reference point of the bed, and the reference cylinder is used to obtain signal data from the magnetic resonance imaging system, thereby determining the alignment accuracy between the bed and the magnetic resonance scanning device through the data obtained by the magnetic resonance imaging system.

[0062] Exemplarily, the reference mold 1 includes a medium filled in the housing 2. Exemplarily, it may fill the reference cylinder 3, fill the space between the body of the housing 2 and the reference cylinder 3, or fill all the empty space within the housing 2. Alternatively, air may also be considered a medium. Exemplarily, embodiments in which the housing 2 has a vacuum region are not excluded.

[0063] The medium can contact both the inner and outer walls of the reference cylinder 3. In other embodiments, the cylinder wall of the reference cylinder 3 can be hollow and filled with the medium. For example, the medium is water. During magnetic resonance imaging, the long T2 characteristic of water, which results in slow decay of the transverse magnetization vector, can be utilized to present a different signal in the image compared to the reference cylinder 3.

[0064] For example, when using the reference mold 1, the reference mold 1 can be placed with the axis of the reference cylinder 3 parallel to the Y-axis direction. Since the reference cylinder 3 is rotationally symmetrical about its axis, the reference mold 1 can be used as a reference even if the angle of rotation of the reference mold 1 about this axis is not strictly limited.

[0065] In an exemplary implementation, such as Figure 1 and Figure 3 As shown, the reference phantom 1 also includes a reference column 5 located inside and coaxial with the reference cylinder 3. The reference cylinder 3 is filled with a medium. By bringing the medium, including water, into contact with the reference column 5, the medium and the reference column 5 can be used to obtain different signals by the magnetic resonance scanning device 10. The axis of the reference column 5 also coincides with the central axis represented by the centering mark 4, and the reference column 5 can be used to preliminarily qualitatively determine the centering accuracy between the magnetic resonance scanning device 10 and the bed 82. Exemplarily, the diameter of the reference column 5 can be 0.5 mm, 1 mm, 2 mm, etc. In some embodiments, the radius of the reference column 5 can be set to the value of the minimum centering accuracy requirement. Different models of magnetic resonance imaging systems 7 can set this minimum centering accuracy requirement according to actual conditions in order to realize their magnetic resonance imaging functions. The bed 82 and the magnetic resonance scanning device 10 may also be perfectly aligned to achieve the highest centering accuracy requirement of zero deviation.

[0066] Figure 4 A cross-sectional structure parallel to the xy plane and passing through the axis of the reference cylinder 3 is shown. This cutting plane can be a second cutting plane 102. A first cutting plane 101 also passes through the axis of the reference cylinder 3 and is perpendicular to the second cutting plane 102. The reference cylinder 3 is cut into a first section 31 on the left side of the figure and a second section 32 on the right side of the figure. Exemplarily, the mean diameter D0 of the cylinder wall of the reference cylinder 3 is 50 mm, and the semi-mean diameter R0 is 25 mm. The outer diameter or inner diameter of the cylinder wall of the reference cylinder 3 can also be set to, for example, 50 mm.

[0067] refer to Figure 14 In some cases, after the bed 82 of the magnetic resonance imaging system 7 enters the scanning cavity 110, the reference point of the bed 82 (i.e., the centering mark 4 of the reference phantom 1) may deviate from the center of the field of view S along the Z-axis. For example... Figure 5As shown, the projection of the field of view center S onto the detection plane (the plane perpendicular to the Y-axis) is fixed. After the bed 82 enters the scanning cavity 110, the center point represented by the centering mark 4 deviates by ΔZ from the projection of the field of view center S onto the detection plane along the Y-axis. Therefore, this embodiment provides an evaluation method for obtaining the centering accuracy of the magnetic resonance scanning device 10 and the bed 82 in the detection plane of the magnetic resonance imaging system 7. Exemplarily, the centering accuracy can be decomposed into the deviation along the X-axis and the deviation along the Z-axis. For example, when there is no deviation or negligible deviation along the X-axis between the magnetic resonance scanning device 10 and the bed 82, the value of ΔZ can be obtained.

[0068] refer to Figure 13-14 ,like Figure 6 As shown, the evaluation method 1000 may include the following steps.

[0069] In step S101, the reference phantom is placed on the bed, and the centering mark of the reference phantom is positioned at the reference point of the bed. Specifically, the reference phantom 1 can be placed with the axis of the reference cylinder 3 perpendicular to the detection surface (or the axis of the reference cylinder 3 along the Y-axis) and the centering mark 4 of the reference phantom 1 aligned with the reference point of the bed 82. For example, in step S101, the laser lamp 9 is turned on, and the bed 82 is in its first state, i.e., the bed 82 is located outside the magnetic resonance scanning device 10, and the laser lamp 9 illuminates the reference point of the bed 82. The laser lamp 9 can project a laser carrying graphic information, with the laser direction along the Y-axis, thereby illuminating the centering mark 4. The position of the reference phantom 1 can be adjusted in the X-axis and Z-axis directions so that the centering mark 4 of the reference phantom 1 coincides with the laser beam of the laser lamp 9, i.e., the center of the centering mark 4 of the reference phantom 1 is illuminated by the laser beam of the laser lamp 9 and coincides with the laser beam.

[0070] Exemplarily, in step S102, a command to move the bed is executed. Specifically, the bed 82 changes from a first state to a second state. Exemplarily, the composite motion bed 8 of the magnetic resonance imaging system 7 can be controlled by a program, and then, after executing the command, the bed 82 is moved from outside the scanning cavity 110 of the magnetic resonance scanning device 10 to inside the scanning cavity 110 of the magnetic resonance scanning device 10. Theoretically, the reference point of the bed 82 should coincide with the projection of the center of the field of view S of the scanning cavity 110 along the Y-axis, and the reference phantom 1 moves with the bed 82, and the centering mark 4 should also coincide with the projection of the center of the field of view S along the Y-axis. In reality, when there is a deviation along the Z-axis, the reference point of the bed 82, that is, the centering mark 4 of the reference phantom 1, is located in a first position along the Z-axis relative to the center of the field of view S.

[0071] Step S103: A first image of the reference phantom in a first plane parallel to the first direction can be obtained using a magnetic resonance imaging system. Exemplarily, the first plane may be parallel to the Y-axis and X-axis directions, and the perpendicular line of the first plane may be parallel to the Z-axis direction. Specifically, the first image includes a first pattern and a second pattern corresponding to the wall of the reference cylinder.

[0072] Step S104: Determine the first position of the field of view center of the magnetic resonance scanning device relative to the centering mark along the perpendicular direction of the first surface, based on the first pattern and the second pattern. The perpendicular direction of the first surface may be parallel to the Z-axis direction and may be located within the detection surface.

[0073] For example, in step S105, the alignment accuracy between the bed and the magnetic resonance scanning device in the detection plane is determined based on the first position. When the bed 82 and the magnetic resonance scanning device 10 have only a deviation along the Z-axis, the alignment accuracy can be considered to be the deviation reflected by the first position.

[0074] For example, the evaluation method 1000 uses the reference phantom 1 provided in the foregoing embodiments. (See reference...) Figure 5 The intersection of the first cut surface 101 and the second cut surface 102 is the position of the axis indicated by the center mark 4.

[0075] In some embodiments, step S101 includes placing the reference phantom 1 in a first direction perpendicular to the detection surface, that is, setting the cross-section of the reference cylinder 3 to be parallel to the detection surface of the magnetic resonance scanning device. For example... Figure 13 As shown, the centering mark 4 is used to determine that the central axis represented by the centering mark 4 is located at a specified position on the bed 82 of the magnetic resonance imaging system 7 when the reference phantom 1 is placed on the bed 82. This specified position may be, for example, a reference point on the bed 82 that can be determined by illumination from the laser lamp 9.

[0076] In step S101, the laser lamp 9 can be aligned with the centering mark 4. Then, in step S102, the reference phantom 1 is kept fixed on the bed 82. The magnetic resonance imaging system 7 can perform the alignment operation; for example, the magnetic resonance imaging system 7 is configured with a "one-click magnet centering" program. After executing this program, theoretically, the field of view center S of the magnetic resonance scanning device 10 coincides with the reference point of the bed 82 and the centering mark 4 of the reference phantom 1 projected along the Y-axis. However, in reality, the field of view center S and the reference point of the bed 82 may differ in the detection plane, for example... Figure 5 The deviation ΔZ shown is given.

[0077] like Figure 7As shown, the magnetic resonance imaging system 7 obtains a first image 61 of the reference phantom 1 within a first surface. This first surface is parallel to the X-axis and Y-axis directions, and is also parallel to the second cross-section 102 and perpendicular to the first cross-section 101. Specifically, the first image 61 includes a first pattern 310 and a second pattern 320 corresponding to the wall of the reference cylinder 3.

[0078] If the magnetic resonance scanning device 10 and the bed 82 are misaligned only in the Z-axis direction and not in the X-axis direction, then... Figure 7 As shown, the pattern of the reference model 1 is approximately located in the middle of the first image field of view 610 of the first image 61 along the X-axis. Figure 7 The first image 61 shown belongs to the first plane parallel to the second cut plane 102. Figure 7 The double-dotted outline diagram illustrates the theoretical pattern of the cylinder wall of the reference cylinder 3 in the second cross-section 102. It can be understood that the distance L1 between the first tangent 311 and the second tangent 321 is less than the mean diameter D0 of the cylinder wall of the reference cylinder 3, and the distance L2 between the first tangent 311 and the central axis of the reference mold 1 is less than the semi-mean diameter R0 of the cylinder wall. The mean diameter D0 of the cylinder wall of the reference cylinder 3 is a preset value, for example, 50 mm, and therefore the semi-mean diameter R0 of the cylinder wall is 25 mm.

[0079] refer to Figure 5 The cylinder shown with the mean diameter D0 of the wall of the reference cylinder 3 as its diameter can be called the reference cylindrical surface. The first surface shown in the first image 61 intersects the reference cylindrical surface at the first tangent 311 and the second tangent 321. The distance L1 between the first tangent 311 and the second tangent 321 is less than the mean diameter D0. The first tangent 311 and the second tangent 321 are symmetrical with respect to the first tangent plane 101, so the distance L2 between the first tangent 311 and the first tangent plane 101 along the X-axis is half of the distance L1 between the first tangent 311 and the second tangent 321.

[0080] Within the detection plane, the deviation ΔZ between the field of view center S of the magnetic resonance scanning device 10 and the central axis of the reference phantom 1 (the reference point of the bed 82) satisfies:

[0081]

[0082] The mean diameter D0 is a known value, and L1 can be obtained from the first pattern 310 and the second pattern 320 in the first image 61. That is, the deviation ΔZ can be determined from the first pattern 310 and the second pattern 320.

[0083] The deviation ΔZ is the actual deviation between the reference point of the bed 82 and the field of view center S of the magnetic resonance scanning device 10 along the Z-axis, or it can be regarded as the deviation between the actual position and the theoretical position of the bed 82 in the second state. In step S104, the first position of the field of view center S of the magnetic resonance scanning device 10 relative to the centering mark 4 along the Z-axis is determined according to the first pattern 310 and the second pattern 320. Since the centering mark 4 is consistent with the reference point of the bed 82, the result obtained by determining the centering accuracy of the magnetic resonance scanning device 10 and the bed 82 in the detection plane according to the first position in step S105 is: the centering accuracy of the magnetic resonance scanning device 10 and the bed 82 is the deviation ΔZ.

[0084] For example, the first image 61 also includes a first housing pattern 21 and a second housing pattern 22 corresponding to the housing 2. (See reference) Figure 4 and Figure 7 The box 2 can be a cube. When its two pairs of sidewalls along the Z-axis are placed along the X-axis and Z-axis respectively, the patterns of the corresponding sidewalls in the images parallel to the second cut plane 102 can remain unchanged. For example, the first box pattern 21 and the second box pattern 22 are shown in the first image 61.

[0085] In an exemplary embodiment, the first image 61 includes a fifth pattern 50 corresponding to the reference column 5. When the deviation between the center of the field of view S of the magnetic resonance scanning device 10 and the reference point of the bed 82 is small, the fifth pattern 50 will appear in the first image 61. At this time, it can be known without any calculation that the deviation between the center of the field of view S of the magnetic resonance scanning device 10 and the reference point of the bed 82 is less than the radius of the reference column 5. For example, the diameter of the reference column 5 is 1 mm, and in step S105, the alignment accuracy can be directly and roughly determined to be a deviation of no more than 0.5 mm. Further, more precise calculations can still be performed using formula (1) to obtain a finer value for the alignment accuracy.

[0086] like Figure 8 As shown, exemplarily, if the deviation between the field of view center S of the magnetic resonance scanning device 10 and the reference point of the bed 82 is too large, the first image 61 may not contain a pattern corresponding to the reference column 5. In this case, it is known that the deviation between the field of view center S of the magnetic resonance scanning device 10 and the reference point of the bed 82 is greater than the radius of the reference column 5. Exemplarily, the radius of the reference column 5 can be set to the value required for the minimum centering accuracy.

[0087] In step S103, the following was obtained Figure 8 After the first image 61 shown, step S104 can still be performed using formula (1) to obtain the centering accuracy. For example, the circle in the reference mold 1 with the inner or outer diameter of the cylinder wall of the reference cylinder 3 as its diameter can also be controlled to be the reference circle.

[0088] Figure 8 As shown, the middle diameter of the reference cylinder 3 is the diameter of the reference circle. The position of the first tangent 311 can be obtained from the two sides of the first pattern 310 in the X-axis direction, thus eliminating the graphic error of the two sides of the first pattern 310 in the X-axis direction; the position of the second tangent 321 can be obtained from the two sides of the second pattern 320 in the X-axis direction, thus eliminating the graphic error of the two sides of the second pattern 320 in the X-axis direction.

[0089] In an exemplary implementation, such as Figure 9 As shown, the field of view center S of the magnetic resonance scanning device 10 and the reference point of the bed 82 may deviate in the X-axis and Z-axis directions within the detection plane.

[0090] like Figure 10 As shown, this disclosure provides another evaluation method 1000. The evaluation method 1000 includes the aforementioned steps S101 to S105, and may also include the following steps.

[0091] Step S106: Obtain a second image of the reference phantom in a second plane parallel to the first direction and perpendicular to the first plane using a magnetic resonance imaging system. The second image includes a third pattern and a fourth pattern corresponding to the wall of the reference cylinder. The second plane may be parallel to the Y-axis direction and parallel to the Z-axis direction.

[0092] Step S107: Determine the second position of the field of view center of the magnetic resonance scanning device relative to the centering mark along the perpendicular direction of the second surface, based on the third and fourth patterns. The perpendicular direction of the second surface can be parallel to the X-axis direction. The order of steps S106 and S103 can be adjusted or both can be performed in parallel.

[0093] For example, step S105 may specifically include determining the alignment accuracy of the bed and the magnetic resonance scanning device in the detection plane based on the first position and the second position.

[0094] like Figure 11 As shown and referenced Figure 9 After the mating device aligns with the centering mark 4, the magnet executes a procedure such as "one-click entry into the magnet center," thereby obtaining the first image 61. The first image 61 presents an image at a point parallel to the second sectional plane 102 and passing through the center of the field of view S of the magnetic resonance scanning device 10. This sectional plane intersects the reference circle represented by the reference cylinder 3 at the first tangent 311 and the second tangent 321. Figure 11 As shown, since the field of view center S of the magnetic resonance scanning device 10 is offset in the X-axis direction compared to the mating device, each pattern can be offset to the left in the X-axis direction compared to the central axis of the first image field of view 610. In step S104, the deviation ΔZ between the field of view center S of the magnetic resonance scanning device 10 and the central axis of the mating device along the Z-axis direction can be obtained using formula (1).

[0095] like Figure 12 As shown and referenced Figure 9 The magnet can also acquire a second image 62. The second image 62 presents an image of a section parallel to the first tangent plane 101 and passing through the center s of the magnet. This tangent plane intersects the reference circle represented by the reference cylinder 3 at a third tangent line 331 and a fourth tangent line 341. (As...) Figure 12 As shown, since the center s of the magnet is offset in the Z-axis direction compared to the center of the mating device, each pattern can be offset to the right in the Z-axis direction relative to the central axis of the second image field of view 620.

[0096] Figure 12 In the second image 62 shown, the distance L3 between the third tangent 331 and the fourth tangent 341 can be obtained based on the third pattern 330 and the fourth pattern 340. For example... Figure 11 The distance L4 between the third tangent 331 and the second tangent plane 102 is less than the semi-middle diameter R0 of the reference cylinder 3. The second image 62 may also include the third box pattern 23, the mark pattern 40, and the sixth pattern 51 corresponding to the reference column 5, etc.

[0097] In step S107, the deviation ΔX along the X-axis between the field of view center S of the magnetic resonance scanning device 10 and the reference point of the bed 82 can be obtained using the following formula:

[0098]

[0099] Looking back Figure 9 This allows us to obtain the offsets of the field of view center S of the magnetic resonance scanning device 10 from the reference point of the bed 82 in two directions. The actual offset ΔS of the field of view center S of the magnetic resonance scanning device 10 from the reference point of the bed 82 within the detection plane can be:

[0100]

[0101] Subsequently, in some embodiments, in step S105, the offset of the field of view center S of the magnetic resonance scanning device 10 from the reference point of the bed 82 in two directions can be converted into positional degree φS (or coaxiality):

[0102]

[0103] The evaluation method provided in this disclosure can simply, quickly and relatively accurately evaluate the alignment accuracy between the bed and the magnetic resonance scanning equipment.

[0104] like Figure 13 and Figure 14 As shown, this disclosure also provides a magnetic resonance imaging system 7, which may include a composite motion bed 8, a magnetic resonance scanning device 10, and the aforementioned reference phantom 1.

[0105] The composite motion bed 8 includes a base 81 and a bed body 82. The base 81 can be fixedly connected to the housing of the magnetic resonance scanning device 10. The bed body 82 can be used to place the object to be scanned. The bed body 82 can move along the Z-axis direction. In some embodiments, the height of the bed body 82 in the Y-axis direction can be adjusted. When the bed body 82 is in a first state, the reference point of the bed body 82 can be located at a specified position relative to the external space.

[0106] The magnetic resonance scanning device 10 is used to realize the function of magnetic resonance imaging. The magnetic resonance scanning device 10 may include components such as a magnet, excitation coil, and induction coil, and may also be equipped with a composite function coil. The magnetic resonance scanning device 10 has a scanning cavity 110, and the bed 82 can move along the Z-axis direction to enter the scanning cavity 110. The field of view center S of the magnetic resonance scanning device 10 may refer to the center of the magnet. In some embodiments, the magnetic resonance scanning device 10 can generate images at the same spatial position as the first image 61 and the second image 62 in any of the above embodiments, as well as images at other positions. In some embodiments, the magnetic resonance imaging system 7 is an animal magnetic resonance imaging system, and the bed 82 can be connected to an animal chamber, where the object to be scanned, such as a mouse, can be placed.

[0107] The magnetic resonance imaging system provided in this disclosure can perform centering accuracy assessment as needed during its service life to ensure the precise relative position of the bed and the magnetic resonance scanning equipment. This magnetic resonance imaging system also provides high image quality.

[0108] For example, the magnetic resonance imaging system 7 includes a laser lamp 9. When the bed 82 is in a first state, the laser from the laser lamp 9 can illuminate a reference point of the bed 82.

[0109] Exemplarily, the computer system may be a component of the magnetic resonance imaging system 7. In other embodiments, the computer system may also be separately configured and communicatively connected to the magnetic resonance imaging system 7. In some embodiments, the computer system may perform the method steps for calculating the centering accuracy of the bed and the magnetic resonance scanning device in any of the above embodiments. The computer system of the magnetic resonance imaging system 7 includes a processor 702 and a memory 703 connected via a bus 701. The memory 703 stores a computer program, and the processor 702 executes the computer program to perform the steps of the above method embodiments. Optionally, the computer system may also include a network interface, a display screen, and an input / output device 704. The processor 702 of the computer system provides computing and control capabilities. The memory 703 of the computer system includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The network interface of the computer system is used for communication with external terminals via a network connection. Optionally, the computer system may be a server, a personal computer, a personal digital assistant, or other terminal devices, such as tablets, mobile phones, etc., or it may be a cloud or remote server. The embodiments of this application do not limit the specific form of the computer system.

[0110] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be written in any one or more programming languages. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory.

[0111] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0112] The above-described various forms of processes can be used, and steps can be reordered, added, or deleted. The steps described in the embodiments of this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution provided by the embodiments of this disclosure can be achieved, and no limitation is imposed herein.

[0113] The embodiments described above are merely illustrative of several implementations of this disclosure, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the disclosed patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this disclosure, and these all fall within the protection scope of this disclosure. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A reference phantom for use as a reference to obtain the alignment accuracy of the bed and the magnetic resonance scanning device in the detection plane of a magnetic resonance imaging system. Its features are, The reference phantom includes: A housing having a first end face, the housing being filled with a medium; A concentric mark is located on the first end face; and A reference cylinder is located inside the housing, the axis of the reference cylinder coincides with the center of the centering mark, and the reference cylinder is filled with the medium, which is used to obtain different signals from the magnetic resonance scanning device.

2. The reference phantom according to claim 1, wherein, The medium includes water.

3. The reference phantom according to claim 1, wherein, The reference mold also includes a reference column located inside the reference cylinder and coaxial with the reference cylinder.

4. The reference phantom according to claim 3, wherein, The radius of the reference post is matched to the minimum centering accuracy requirement.

5. The reference phantom according to claim 1, wherein, The box is a cube.

6. An evaluation method for obtaining the alignment accuracy of the bed and the magnetic resonance scanning device in the detection plane of a magnetic resonance imaging system. Its features are, The evaluation method includes: A reference phantom as described in any one of claims 1 to 5 is placed on the bed, and the centering mark of the reference phantom is located at a reference point on the bed; wherein the bed is in a first state located outside the scanning cavity of the magnetic resonance scanning device; The bed is moved from outside the scanning cavity of the magnetic resonance scanning device to inside the scanning cavity of the magnetic resonance scanning device to make the bed in a second state. Then, the magnetic resonance scanning device obtains a first image of the reference phantom in a first plane parallel to the axis of the reference cylinder. The first image includes a first pattern and a second pattern corresponding to the cylinder wall of the reference cylinder. The first position of the field of view center of the magnetic resonance scanning device relative to the centering mark is determined according to the first pattern and the second pattern along the perpendicular direction of the first surface.

7. The evaluation method according to claim 6, wherein, The evaluation method also includes: A second image of the reference phantom is obtained by the magnetic resonance scanning device in a second plane that is parallel to the axis of the reference cylinder and perpendicular to the first plane, wherein the second image includes a third pattern and a fourth pattern corresponding to the cylinder wall of the reference cylinder; The second position of the field of view center of the magnetic resonance scanning device relative to the centering mark is determined according to the third pattern and the fourth pattern along the perpendicular direction of the second surface; and The alignment accuracy between the bed and the magnetic resonance scanning device in the detection plane is determined based on the first position and the second position.

8. The evaluation method according to claim 6, wherein, The first image includes a fifth pattern corresponding to the reference pillar; as well as The alignment accuracy is determined based on the radius values ​​of the fifth pattern and the reference column.

9. A magnetic resonance imaging system, characterized in that, include: Magnetic resonance imaging (MRI) scanners have a scanning cavity; The bed is movable relative to the magnetic resonance scanning device along a first axis within the detection plane, and has a first state located outside the scanning cavity of the magnetic resonance scanning device and a second state located inside the scanning cavity of the magnetic resonance scanning device; as well as The reference phantom as described in any one of claims 1 to 5 is used as a reference to obtain the alignment accuracy of the bed and the magnetic resonance scanning device in the detection plane.

10. The magnetic resonance imaging system according to claim 9, wherein, Also includes: A laser lamp, located outside the scanning cavity of the magnetic resonance scanning device, is used to illuminate the reference point of the bed.

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