Medical imaging system and rotation error compensation method and storage medium thereof

Abstract

The present invention relates to the field of medical equipment technology, and provides a medical imaging system and a rotation error compensation method and storage medium thereof. The compensation method of the present invention can select an appropriate compensation interpolation boundary based on the different motion states of a magnetic scale, thereby defining the transition segment of the magnetic scale based on the selected compensation interpolation boundary and the factory interpolation boundary. Specifically, different transition segments are determined based on the different motion states of the magnetic scale, and the interpolation compensation transition segment is predicted based on a kinematic function. This ensures that the reading head maintains normal counting when transitioning through a virtual gap segment of the magnetic scale and reduces the probability of the reading head misreading a false zero signal during the interpolation process, thereby ensuring the quality of medical images.

Description

Technical Field

[0001] The present invention relates to the technical field of medical equipment, and in particular to a medical imaging system and a rotation error compensation method and a storage medium thereof. Background Art

[0002] In medical imaging systems, such as CT systems, the rotation of the CT gantry is driven by a motor. The rotation angle and speed of the CT gantry are fed back by a magnetic scale mounted on the CT gantry. The magnetic scale has a zero position. When the reader reaches this zero position, it reads the zero signal fed back by the magnetic scale, and the reader's count is reset to zero.

[0003] Currently, due to assembly process issues, the magnetic scale cannot completely fit around the CT gantry. After the magnetic scale is installed on the CT gantry, a gap area will exist, which means that the magnetic scale is not a complete ring. Due to the presence of external medical devices (such as tubes and detectors), there is a high probability of electromagnetic interference in the gap area of ​​the magnetic scale, resulting in a false zero signal in the gap area of ​​the magnetic scale. This will cause the reader to read the false zero signal and reset the counting result prematurely. This may cause the reader to be unable to count later or the accuracy of the scanned medical image to deviate significantly, affecting the diagnosis results.

[0004] Currently, some solutions have emerged to address the aforementioned false zero point problem. These solutions typically define a compensation segment by setting a fixed judgment boundary and a factory-set boundary for the magnetic scale. The gap in the magnetic scale is located within this compensation segment. During the rotation of the magnetic scale, the compensation segment is interpolated and compensated using a motion function established before the fixed judgment boundary, allowing the reader to at least transition through the gap in the magnetic scale, thereby filtering out false zero points or reducing the probability of false zero points. This ensures that the reader can still count normally and maintains the image quality of the medical imaging system. However, the current solution does not take into account the actual motion state of the CT gantry (which may be operating in uniform circular motion or accelerated or decelerated circular motion). Therefore, the fixed judgment boundary solution in the existing technology still results in a high probability of the reader reading a false zero point. Summary of the Invention

[0005] The present invention provides a medical imaging system and a rotation error compensation method and storage medium thereof, aiming to prevent the reading head from misreading a false zero point signal when the reading head transitions through a gap area of ​​a magnetic scale, thereby ensuring the quality of medical images.

[0006] To achieve the above-mentioned object, based on a first aspect of the present invention, the present invention provides a method for compensating rotational errors of a medical imaging system, comprising:

[0007] Configuring at least two different compensation interpolation boundaries on a physical circumferential segment of a magnetic scale mounted on a rotating frame, and selecting one of the compensation interpolation boundaries according to a motion state of the magnetic scale;

[0008] The selected compensation interpolation boundary is limited to be located on the upstream side of the rotation direction of the magnetic scale and the factory interpolation boundary of the magnetic scale is limited to be located on the downstream side of the rotation direction of the magnetic scale, thereby defining a transition section of the magnetic scale;

[0009] interpolating and compensating the transition section according to a kinematic function established by the magnetic scale and in accordance with a rotation direction of the magnetic scale;

[0010] The compensation interpolation boundary and the factory interpolation boundary are located on both sides of the virtual gap segment of the magnetic scale, and the rotation direction of the magnetic scale is the direction defined by the compensation interpolation boundary, the virtual gap segment and the factory interpolation boundary in sequence.

[0011] Optionally, the step of establishing the kinematic function of the magnetic scale includes:

[0012] The factory interpolation boundary of the magnetic scale is limited to be located on the upstream side of the rotation direction of the magnetic scale and the selected compensation interpolation boundary is located on the downstream side of the rotation direction of the magnetic scale, thereby defining the sampling section of the magnetic scale;

[0013] A kinematic function of the magnetic scale is established according to each angular scale in the sampling segment and the sampling time corresponding to the angular scale.

[0014] Optionally, the compensation interpolation boundary selected when the magnetic scale performs uniform circular motion is larger than the compensation interpolation boundary selected when the magnetic scale performs variable speed circular motion.

[0015] Optionally, all of the compensation interpolation boundaries are located within a 1 / 4 circumference range from the virtual gap segment.

[0016] Optionally, the compensation method further includes:

[0017] Analyze the zero point signal to determine an expected zero point boundary on the magnetic scale corresponding to the zero point signal;

[0018] When the expected zero point boundary is less than or equal to the selected compensation interpolation boundary and greater than the factory interpolation boundary, maintaining the reading head in a counting working state for the sensor signal of the magnetic scale;

[0019] When the expected zero point boundary is greater than the selected compensation interpolation boundary, the read head is controlled to be reset only once, and the sensing signal of the magnetic scale is re-detected and counted.

[0020] Optionally, the physical circumferential segment of the magnetic scale has a real zero point boundary, and the real zero point boundary is located between the virtual notch segment and the factory interpolation boundary; the compensation method further includes:

[0021] If the image result of the medical imaging system does not meet the preset conditions, it is determined that the expected zero point boundary is between the compensated interpolation boundary and the real zero point boundary in the transition section, and the medical imaging system is calibrated according to a preset correction protocol.

[0022] Optionally, the image result of the medical imaging system not meeting a preset condition includes that motion artifacts appear in the image result of the medical imaging system.

[0023] Based on the second aspect of the present invention, the present invention further provides a medical imaging system, comprising a magnetic scale, a rotating frame, a read head, and a processor, wherein the magnetic scale is coaxially fixed to the rotating frame, the read head is fixed relative to the center position of the rotating frame, and the processor is configured to execute:

[0024] configuring at least two different compensation interpolation boundaries on a physical circumferential segment of the magnetic scale, and selecting one of the compensation interpolation boundaries according to a motion state of the magnetic scale;

[0025] The selected compensation interpolation boundary is limited to be located on the upstream side of the rotation direction of the magnetic scale and the factory interpolation boundary of the magnetic scale is limited to be located on the downstream side of the rotation direction of the magnetic scale, thereby defining a transition section of the magnetic scale;

[0026] interpolating and compensating the transition section according to a kinematic function established by the magnetic scale and in accordance with a rotation direction of the magnetic scale;

[0027] The compensation interpolation boundary and the factory interpolation boundary are located on both sides of the virtual gap segment of the magnetic scale, and the rotation direction of the magnetic scale is the direction defined by the compensation interpolation boundary, the virtual gap segment and the factory interpolation boundary in sequence.

[0028] Optionally, the medical imaging system further includes a rotating motor, the rotating gantry is configured to be on a rotor of the rotating motor, and the read head is mounted on a stator of the rotating motor.

[0029] Based on the third aspect of the present invention, the present invention further provides a storage medium storing a readable and writable program, which, when executed, can implement the above-mentioned method for compensating for rotation errors of a medical imaging system.

[0030] In summary, in the medical imaging system and its rotation error compensation method and storage medium provided by the present invention, the compensation method includes: configuring at least two different compensation interpolation boundaries on a physical circumferential segment of a magnetic scale installed on a rotating frame, and selecting one of the compensation interpolation boundaries according to the motion state of the magnetic scale; limiting the selected compensation interpolation boundary to be located on the upstream side of the rotation direction of the magnetic scale and the factory interpolation boundary of the magnetic scale to be located on the downstream side of the rotation direction of the magnetic scale, thereby defining the transition section of the magnetic scale; interpolating and compensating the transition section according to the kinematic function established for the magnetic scale and in accordance with the rotation direction of the magnetic scale; wherein the compensation interpolation boundary and the factory interpolation boundary are located on both sides of the virtual notch segment of the magnetic scale, and the rotation direction of the magnetic scale is the direction defined in sequence by the compensation interpolation boundary, the virtual notch segment, and the factory interpolation boundary.

[0031] Compared to prior art approaches that simply set a fixed boundary value without considering the actual motion state of the magnetic scale, the compensation method of the present invention sets at least two different compensation interpolation boundaries. An appropriate compensation interpolation boundary can be selected based on the different motion states of the magnetic scale. The selected compensation interpolation boundary and the factory interpolation boundary are then used to define the transition section of the magnetic scale. This means that different transition sections are determined based on the different motion states of the magnetic scale. The interpolation compensation transition section is then predicted based on the kinematic function, ensuring that the reader continues to count properly when transitioning through virtual gaps in the magnetic scale and reducing the probability of the reader misreading false zero signals during the interpolation process, thereby ensuring the quality of medical images. Furthermore, the compensation interpolation boundary selected when the magnetic scale is in uniform circular motion is larger than the compensation interpolation boundary selected when the scale is in variable speed circular motion. Thus, when the magnetic scale is in uniform circular motion, the defined transition section is smaller, the probability of a false zero signal is also lower, and even if the reader misreads a false zero signal, data loss from the interpolation compensation is minimal. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Those skilled in the art will appreciate that the accompanying drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.

[0033] Figure 1 is a schematic diagram of a medical imaging system;

[0034] Figure 2 This is a schematic diagram of a magnetic scale;

[0035] Figure 3 yes Figure 2 Enlarged view of the middle X section;

[0036] Figure 4 is a schematic diagram of a method for compensating rotational errors of a medical imaging system according to an embodiment of the present invention;

[0037] Figure 5 FIG. 1 is a schematic diagram of various boundaries on a magnetic scale according to an embodiment of the present invention.

[0038] In the attached figure:

[0039] 10-rotating gantry; 100-annular scanning cavity; 20-tube; 30-detector; 40-scanning bed; 50-patient; 60-magnetic scale; 601-virtual gap segment; 70-rotor; a-variable speed compensation interpolation boundary; b-uniform speed compensation interpolation boundary; c-first physical boundary; d-second physical boundary; e-true zero point boundary; f-factory interpolation boundary. DETAILED DESCRIPTION

[0040] To make the objects, advantages, and features of the present invention more clearly apparent, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale. They are only used to conveniently and clearly assist in illustrating the purposes of the embodiments of the present invention. In addition, the structures shown in the drawings are often part of the actual structure. In particular, different drawings may need to illustrate different focuses and sometimes use different scales.

[0041] As used in the present invention, the singular forms "a", "an", and "the" include plural referents, the term "or" is generally used to include "and / or", the term "several" is generally used to include "at least one", and the term "at least two" is generally used to include "two or more". In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features specified as "first", "second", and "third" may explicitly or implicitly include one or at least two of the features, "one end" and "the other end" and "proximal end" and "distal end" generally refer to two corresponding parts, which not only include endpoints, and the terms "mounted", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be a communication between two elements or an interaction relationship between two elements. In addition, as used in the present invention, "one element is disposed on another element" generally only indicates that there is a connection, coupling, cooperation, or transmission relationship between the two elements, and the connection, coupling, cooperation, or transmission between the two elements may be direct or indirect through an intermediate element. It should not be understood as indicating or implying a spatial positional relationship between the two elements. That is, one element can be in any orientation, such as inside, outside, above, below, or to one side of another element, unless the content clearly indicates otherwise. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] Figure 1 is a schematic diagram of a medical imaging system. Figure 1As shown, a medical imaging system, which may specifically be a computed tomography (CT) system, includes at least a rotating gantry 10, a tube 20, a detector 30, and a scanning table 40. The tube 20 and the detector 30 are core components of the CT system for scanning and imaging. The tube 20 emits electron beams (such as X-rays), which pass through a patient 50 and are received by the detector 30. The tube 20 and the detector 30 cooperate to perform a radiographic scan of the patient 50. The rotating gantry 10 serves as a mechanical support structure for mounting the tube 20 and the detector 30. The rotating gantry 10 has an annular scanning cavity 100, with the tube 20 and the detector 30 symmetrically mounted on either side of the annular scanning cavity 100. The scanning table 40 serves as a carrier for the patient 50 to enter and exit the annular scanning cavity 100. In actual application scenarios, the patient 50 lies flat on the scanning bed 40. As the scanning bed 40 enters the annular scanning cavity 100, the rotating frame 10 synchronously drives the tube 20 and the detector 30 to rotate (specifically, circular motion around the central axis of the scanning cavity), thereby performing a spiral scan on the patient 50.

[0043] Typically, a magnetic scale 60 is mounted and fixed on the rotating gantry 10. The magnetic scale 60 is coaxial with the annular scanning cavity 100 and rotates synchronously with the rotating gantry 10. The magnetic scale 60 and the reader cooperate to provide real-time feedback on the rotational position (rotation angle) and rotational speed of the rotating gantry 10, thereby ensuring the accuracy of the medical scan image. In practice, the rotating gantry 10 is driven by a rotary motor. The rotary motor typically has a coaxial stator and rotor. In this embodiment, the rotating gantry 10 is configured as the rotor of the rotary motor, that is, the magnetic scale 60 is coaxially mounted and fixed on the rotor 70 of the motor. In addition, the reader is mounted on the stator and is fixed relative to the center position of the rotating gantry 10. Specifically, the magnetic scale 60 emits a sensor signal for each angular scale. When the rotating gantry 10 moves, it drives the magnetic scale 60 to move synchronously. The reader counts the sensor signal once after passing each angular scale. The count result is then decoded by a decoder to obtain the rotation angle fed back by the magnetic scale 60. Furthermore, the magnetic scale 60 has a zero position, which corresponds to a true zero signal. When the reader reaches the zero position and reads the true zero signal, the reader's count is reset to zero, indicating that the magnetic scale 60 has rotated 360 degrees, or one revolution of the rotating frame 10. After the read head is reset to zero, it can restart counting a new revolution. The sensing signal can be a pulse signal or a level signal. The reader samples and counts the number of pulses or the number of high levels. It should be noted that in this embodiment, the zero position on the magnetic scale 60 is recorded as the true zero boundary e.

[0044] Figure 2 is a schematic diagram of a magnetic scale 60, Figure 3yes Figure 2 The enlarged view of the X part. Figure 2 and Figure 3 As shown, the magnetic scale 60 is roughly annular and is mounted on the rotor 70 of the rotating motor. The magnetic scale 60 is coaxially arranged with the annular scanning cavity 100. In practice, the magnetic scale 60 is not completely annular, but has a gap area. It should be noted that in this embodiment, the gap area of ​​the magnetic scale 60 is named as the virtual gap section 601 of the magnetic scale 60, and the portion of the magnetic scale 60 excluding the virtual gap section 601 is a solid circumferential segment. In actual applications, if the magnetic scale 60 is made into a complete ring shape, the expansion coefficient of the material of the magnetic scale 60 is different from the expansion coefficient of the material of the rotating frame 10, resulting in a low degree of matching. When the complete annular magnetic scale 60 is mounted on the rotating frame 10, the magnetic scale 60 will not be able to fully fit together with the rotating frame 10, and there will be a certain mechanical installation error between the two. Furthermore, considering that the angle control of the rotating frame 10 needs to be extremely precise, the number of sensor signals read by the reader can reach more than 800,000. Usually, in order to reduce mechanical installation errors and ensure the accuracy of the matching between the magnetic scale 60 and the reader, the magnetic scale 60 is not a complete annular structure, and there will be a gap area.

[0045] Since the magnetic scale 60 has a virtual gap section 601, the virtual gap section 601 will not feedback the sensor signal to the reader, resulting in the reader being unable to detect the sensor signal when it is located in the virtual gap section 601, and thus unable to continue to accumulate counts. In addition, the presence of external medical equipment (such as the tube 20) will cause a high probability of electromagnetic interference in the virtual gap section 601, causing the reader to read a false zero signal and reset the count in advance. The current technical solution is to set a fixed value judgment boundary, and collect the motion data of the magnetic scale before the judgment boundary to establish a kinematic function. The kinematic function established before the fixed judgment boundary is interpolated from the fixed judgment boundary to the factory interpolation boundary f (the virtual gap section 601 is located between the fixed judgment boundary and the factory interpolation boundary f) according to the rotation direction of the magnetic scale 60, so that after the magnetic scale 60 rotates through the gap area, the reader can still count normally to transition the gap area of ​​the magnetic scale 60, thereby filtering out false zero signals, which can reduce the probability of the reader reading a false zero signal to a certain extent. Understandably, the magnetic scale 60 rotates synchronously with the rotating gantry 10, and the various motion data fed back by the magnetic scale 60 can also correspond to the motion data of the rotating gantry. However, the current solution does not take into account the actual motion state of the CT gantry (which may be performing uniform circular motion or accelerated or decelerated circular motion). Therefore, the fixed value judgment boundary solution in the existing technology is not adaptable to the various motions of the CT gantry. On the one hand, it may affect the accuracy of the reader counting, and on the other hand, it still causes a high probability of the reader reading a false zero signal.

[0046] In view of this, an embodiment of the present invention provides a medical imaging system and a rotation error compensation method and storage medium thereof to solve the above-mentioned technical problems.

[0047] It can be understood that the gap area of ​​the magnetic scale 60 is named the virtual gap segment 601 of the magnetic scale 60, and the part of the magnetic scale 60 excluding the virtual gap segment 601 is a solid circumferential segment. It can be understood that the complete annular magnetic scale 60 is a solid circumferential segment and a virtual gap segment 601. The corresponding part of the solid circumferential segment can feedback the sensor signal to the reader, and the virtual gap segment 601 has no sensor signal feedback. The magnetic scale 60 has a zero position (real zero boundary e), and this zero position corresponds to the issuance of a real zero signal. The magnetic scale 60 rotates along with the rotating frame 10, so that when the reading head reads the zero position and receives the real zero signal, the counting result of the reading head will be reset to zero to end again. When the reading head reads the zero position, it means that the magnetic scale 60 has rotated back to the initial position, and it can also represent that the magnetic scale 60 has rotated one circle. Through the cooperation of the magnetic scale 60 and the reading head, the angular position of the rotating frame 10 and the tube 20 and detector 30 installed on the rotating frame 10 can be automatically detected in real time, thereby ensuring the accuracy of medical images. Typically, the zero point position of the magnetic scale 60 (the true zero point boundary e) is near the virtual notch segment 601. In the direction of rotation of the rotating frame 10, on the same side of the virtual notch segment 601 as the rotation direction, the positional relationship between the true zero point boundary e and the virtual notch segment 601 satisfies the following: during one rotation of the magnetic scale 60 in the rotational direction, the read head first passes through the virtual notch segment 601 and then reads the true zero point boundary e. Typically, the angle parameter corresponding to the true zero point boundary e is 0°. In other embodiments, the angle parameter corresponding to the true zero point position e can also be 2°, 5°, etc., and those skilled in the art can configure it accordingly based on actual conditions.

[0048] Furthermore, the physical circumferential segment of the magnetic scale 60 also has a factory-interpolated boundary f. This is typically a parameter pre-configured by the manufacturer when the magnetic scale 60 leaves the factory. The two physical boundaries of the virtual gap segment 601 are denoted as the first physical boundary c and the second physical boundary d. Furthermore, the true zero boundary e, the factory-interpolated boundary f, the first physical boundary c, and the second physical boundary d are arranged sequentially along the rotational direction of the magnetic scale 60. That is, during one rotation of the magnetic scale 60, the read head sequentially passes through the true zero boundary e, the factory-interpolated boundary f, the first physical boundary c, the second physical boundary d, and the true zero boundary e. In practice, the distance between the factory-interpolated boundary f and the true zero boundary e is very close, achievable down to the millimeter level. In other words, the rotational direction of the magnetic scale 60 is defined by the arrangement of the first physical boundary c, the second physical boundary d, the true zero boundary e, and the factory-interpolated boundary f on the circumference of the magnetic scale 60.

[0049] Figure 4 This is a method for compensating rotation errors of a medical imaging system according to an embodiment of the present invention. The compensation method includes at least steps S1, S2, and S3.

[0050] S1: Configure at least two different compensation interpolation boundaries on the physical circumference of a magnetic scale mounted on a rotating frame, and select one of these compensation interpolation boundaries based on the motion state of the magnetic scale 60. The compensation interpolation boundaries and the virtual gap segment of the magnetic scale are arranged sequentially along the rotation direction of the magnetic scale. That is, during one rotation of the magnetic scale, the reader first passes through the compensation interpolation boundary and then the virtual gap segment. In other words, the compensation interpolation boundary and the factory interpolation boundary f are located on either side of the virtual gap segment 601 of the magnetic scale 60.

[0051] Figure 5 FIG. 1 is a schematic diagram of the boundaries of the magnetic scale 60 according to an embodiment of the present invention. Figure 5 , further, the real zero point boundary e, the factory interpolation boundary f, the compensation interpolation boundary (a, b), the first physical boundary c and the second physical boundary d are arranged in sequence according to the rotation direction of the magnetic scale 60. Preferably, all the compensation interpolation boundaries are located within 1 / 4 of the circumference of the virtual gap segment, that is, the circumferential distance from the compensation interpolation boundary to the first physical boundary c does not exceed 1 / 4 of the circumference of the magnetic scale, so that the compensation interpolation boundary is as close to the virtual gap segment as possible. Further, according to the foregoing, the rotation direction of the corresponding magnetic scale is the direction defined by the compensation interpolation boundary, the virtual gap segment 601 and the factory interpolation boundary f in sequence, such as Figure 5 Demonstrated clockwise direction.

[0052] In actual application, during the rotation of the magnetic scale 60, the angle parameters corresponding to each boundary increase in sequence. Figure 5 , for example, the rotation direction of the magnetic scale 60 is Figure 5 In the clockwise direction of the demonstration, the corresponding feedback parameters of the true zero point boundary e, the factory interpolation boundary f, the compensation interpolation boundary, the first physical boundary c, and the second physical boundary d increase in sequence.

[0053] Regarding selecting one of the compensation interpolation boundaries according to the motion state of the magnetic scale, different compensation interpolation boundaries are selected corresponding to different motion states of the magnetic scale. It can be understood that the motion state of the magnetic scale 60 is determined according to the circumferential rotation speed of the magnetic scale 60. For example, when the magnetic scale is driven by the rotating frame to perform uniform circular motion, the corresponding compensation interpolation boundary selected is the uniform-speed compensation interpolation boundary b; when the magnetic scale is driven by the rotating frame to perform variable-speed circular motion, the corresponding compensation interpolation boundary selected is the variable-speed compensation interpolation boundary a.

[0054] S2: The selected compensation interpolation boundary is limited to be located on the upstream side of the rotation direction of the magnetic scale and the factory interpolation boundary of the magnetic scale is limited to be located on the downstream side of the rotation direction of the magnetic scale, thereby defining the transition section of the magnetic scale. In addition, the factory interpolation boundary of the magnetic scale is limited to be located on the upstream side of the rotation direction of the magnetic scale and the selected compensation interpolation boundary is limited to be located on the downstream side of the rotation direction of the magnetic scale, thereby defining the sampling section of the magnetic scale. It is understandable that during the rotation of the magnetic scale 60, the upstream side of the rotation direction refers to the area that the reading head passes through first, and the downstream side of the rotation area refers to the area that the reading head passes through later, and the transition section or sampling section is defined by the upstream side and the downstream side. For example, refer to Figure 5 Taking point a as an example, along the direction from a to f, a is located upstream in the rotational direction, and f is located downstream in the rotational direction. The area defined between a and f is the transition section. Correspondingly, along the direction from f to a, f is located upstream in the rotational direction, and a is located downstream in the rotational direction. The area defined between f and a is the sampling section. Thus, the combination of the transition section and the sampling section can be understood as completing a meaningful circular magnetic scale.

[0055] S3: interpolating and compensating the transition section based on the kinematic function established for the magnetic scale 60 and the rotation direction of the magnetic scale.

[0056] As previously mentioned, the reader reading the angular scale should be understood as counting the number of sensor signals from the magnetic scale 60 and converting the counted value into angular position information fed back by the magnetic scale 60. Thus, during the transition section, the kinematic function established by the magnetic scale 60 before the selected compensation interpolation boundary can be used to interpolate and predict the corresponding angular position information at the corresponding time within the transition section, thereby performing interpolation compensation for the transition section.

[0057] Furthermore, the kinematic function of the magnetic scale is established as follows:

[0058] The factory interpolation boundary f of the magnetic scale is defined as being located upstream of the magnetic scale's rotational direction, and the selected compensation interpolation boundary is defined as being located downstream of the magnetic scale's rotational direction, thereby defining the sampling segment of the magnetic scale. For example, when the magnetic scale is driven by a rotating frame to perform uniform circular motion, the corresponding selected compensation interpolation boundary is the uniform compensation interpolation boundary b. The corresponding sampling segment is the direction from f to b, and the physical circumferential segment defined by f and b. When the magnetic scale is driven by a rotating frame to perform variable-speed circular motion, the corresponding selected compensation interpolation boundary is the variable-speed compensation interpolation boundary a. The corresponding sampling segment is the direction from f to a, and the physical circumferential segment defined by f and a. Please refer to the description of step S2 for further understanding; this description will not be expanded upon here.

[0059] The kinematic function of the magnetic scale is established based on each angular scale in the sampling segment and the sampling time corresponding to the angular scale. The sampling time is the time corresponding to the angular scale read by the reader. In this way, in the sampling segment, the sampling time and the angular scale read by the reader at the sampling time can be recorded as a set of sampling arrays. Then, the reader can obtain multiple sets of different sampling arrays as it passes through the sampling segment. Based on the mapping relationship between the angular scale and the sampling time, the kinematic function of the magnetic scale is established based on each set of sampling arrays in the sampling segment.

[0060] In one embodiment, the kinematic function can be established based on linear interpolation. Specifically, the linear interpolation formula is: Among them, (X1, Y1) and (X2, Y2) are two sampling arrays that have been sampled, (X, Y) is the interpolation array that needs to be obtained according to the above formula, X, X1 and X2 represent the sampling time, Y, Y1 and Y2 represent the angular scale, and X is between X1 and X2, and X2 is greater than X1.

[0061] As configured above, on the one hand, by establishing the kinematic function of the magnetic scale, the kinematic function can be used to predict the subsequent movement mode of the magnetic scale 60, and the kinematic function can be used to interpolate the transition section (understandably, the virtual gap section 601 is within the transition section), so that the magnetic scale 60 is compensated as a complete circular ring, and the reader can use the kinematic function to predict the angle count after compensation from the selected compensation interpolation boundary, so that the virtual gap section 601 can be transitioned. The overall system can obtain the current angular position information in the virtual gap section 601 according to the established kinematic function, so that the reader can still work normally for counting according to the corrected and optimized kinematic function; on the other hand, the prior art is equivalent to having only one compensation interpolation boundary (it can be understood that the compensation interpolation boundary in the prior art has been debugged and configured with corresponding parameters by the manufacturer when the magnetic scale leaves the factory). The kinematic function is established in the prior art. The method of calculating the number is basically the same as that of the present embodiment. In this way, the corresponding transition section in the prior art is also a fixed value, which will cause any movement mode of the magnetic scale to interpolate and predict the fixed transition section with the previously established kinematic function. Considering that the magnetic scale 60 will run in different circular motion states, this is obviously unable to meet the actual situation. The reader is prone to misreading the false zero point signal generated by electromagnetic interference when passing through the virtual gap section 601. The present invention sets at least two different compensation interpolation boundaries, and one of the appropriate compensation interpolation boundaries can be selected according to the different motion states of the magnetic scale, thereby limiting the appropriate transition section to allow the kinematic function to interpolate and predict, so as to adapt to the motion state of the magnetic scale and improve the interpolation accuracy of the kinematic function in the virtual gap section, ensure that the reader still works normally when transitioning through the virtual gap section of the magnetic scale and reduce the probability of the reader misreading the false zero point signal during the interpolation process, thereby ensuring the quality of medical images. For example, refer to Figure 5When the frame drives the magnetic scale to make uniform circular motion, the transition section is defined by b and f; when the frame drives the magnetic scale to make variable speed circular motion, the transition section is defined by a and f.

[0062] For example, for example, the uniform circular motion of the magnetic scale 60 running in the sampling section, a kinematic function is established by each group of sampling arrays in the sampling section, the speed parameter in the kinematic function corresponds to 0.1° / s, the angular scale corresponding to b is α, and after time t, the corresponding angular position β in the virtual gap section 601 is β=α+0.1°t, ensuring that the kinematic function is used to interpolate and predict from b, and that there is still angular position signal feedback in the virtual gap section 601. Correspondingly, for example, the uniform accelerated circular motion of the magnetic scale 60 running in the sampling section, a kinematic function is established by each group of sampling arrays in the sampling section, and the speed parameter in the kinematic function corresponds to 0.1° / s 2 , the angle scale corresponding to a is α, and after time t, the corresponding angle position in the virtual gap segment 601 is β=α+0.1°t 2 .

[0063] Preferably, the compensation interpolation boundary selected when the magnetic scale 60 performs uniform circular motion is greater than the compensation interpolation boundary selected when the magnetic scale 60 performs variable speed circular motion. Figure 5 , that is, b is greater than a, ensuring that the transition section (defined by a and f) corresponding to the variable-speed circular motion (such as accelerated / decelerated circular motion) of the magnetic scale 60 is greater than the transition section (the actual circumferential section defined by b and f) corresponding to the uniform circular motion of the magnetic scale 60. In this way, considering that uniform circular motion is relatively stable, a small amount of data can be predicted through motion function interpolation. Furthermore, the smaller the transition section, the lower the probability of a false zero signal. Even if the reader misreads a false zero signal, the data loss from interpolation compensation is minimal.

[0064] In actual application scenarios, there may still be false zero-point signal events in the solid circumference segment and the virtual gap segment 601, resulting in the reader not resetting the e-count at the real zero-point boundary. On the one hand, due to the electromagnetic interference of the internal equipment of the medical imaging system (such as the tube 20) on the magnetic scale 60, a false zero-point signal may appear, which may appear in the solid circumference segment or in the virtual gap segment 601; on the other hand, because the medical imaging system has been used for a long time without being cleaned, electromagnetic interference materials such as iron filings may appear on the solid circumference segment, resulting in a false zero-point signal. Based on this, the compensation method also includes:

[0065] According to the zero-point signal, the zero-point signal is analyzed to correspond to the expected zero-point boundary on the magnetic scale. Generally, the zero-point signal can be detected and analyzed by an external system. It should be noted that the zero-point signal here may be a false zero-point signal generated by electromagnetic interference, so the expected zero-point boundary is not the real zero-point boundary e. Of course, the zero-point signal here may also be a real zero-point signal, then the expected zero-point boundary is also the real zero-point boundary e. Therefore, the expected zero-point boundary analyzed according to the zero-point signal may be located on the physical circular segment (including the real zero-point boundary e) or on the virtual notch segment 601.

[0066] When the expected zero point boundary is less than or equal to the selected compensation interpolation boundary (selected, for example, a or b) and greater than the factory interpolation boundary f, the working state of the read head for the sensor signal of the magnetic scale 60 is maintained, that is, when the parsed expected zero point boundary is located on the physical circumferential segment defined by f and a or f and b, a false zero point signal may appear due to electromagnetic interference from iron filings attached to the magnetic scale 60. At this time, the current working state of the read head is still maintained, and the number of sensor signals of the magnetic scale continues to be read and accumulated. The working states of the magnetic scale 60 and the read head remain unchanged, and then the kinematic function established previously is used to interpolate and compensate from a to f, or from b to f.

[0067] When the expected zero point boundary is greater than the selected compensation interpolation boundary (for example, greater than a or greater than b), the read head is controlled to reset and only reset once, and the sensor signal of the magnetic scale is re-detected and counted. Taking the selected compensation difference boundary as a as an example, when the parsed expected zero point boundary is greater than a, regardless of whether the zero point signal corresponding to the expected zero point boundary at this time is a false zero point signal generated by electrical interference (for example, the tube 20 generates electromagnetic interference on the virtual gap segment) or the zero point signal corresponding to the expected zero point boundary at this time is a true zero point signal, the read head will accept the zero point signal at this time and reset to zero to restart counting (the angle feedback at this time is fed back through the kinematic function). In addition, according to the rotation direction of the magnetic scale, if the expected zero point boundary is not the true zero point boundary e, the expected zero point boundary may be between a and e, or between e and f. To elaborate, when the expected zero point boundary is between a and e, the read head accepts the zero point signal corresponding to this zero point boundary and resets to zero and recounts. As the magnetic scale rotates, when the read head reaches e, it will read the true zero point signal. However, since the read head is reset and only reset once, it has already reset once between a and e. Therefore, the read head will not accept the true zero point signal at this time, but will filter it out. When the expected zero point boundary is between e and f, since the read head will first reach the e position and read the true zero point signal, thereby resetting to zero and recounting. As the magnetic scale rotates, when the read head reaches the expected zero point boundary between e and f, since the read head is reset and only reset once, it has already reset once at e. Therefore, the read head will not accept the false zero point signal between e and f, but will filter it out. In short, according to the direction of rotation of the magnetic scale, the read head will only accept the first zero point signal that appears (which may be a false zero point signal between a and e, or a true zero point signal at e) and reset itself.

[0068] It is understandable that, taking the selected compensation difference boundary as a as an example, when the zero point signal received by the reader for the first time is a false zero point signal located between a and e, the feedback angle position of the magnetic scale for the rotating frame will be inaccurate, thereby causing deviations in the final medical image results. Based on this, the compensation method of this embodiment also includes:

[0069] If the image result of the medical imaging system does not meet the preset conditions, it is determined that the expected zero point boundary is between the compensation interpolation boundary and the real zero point boundary e, and the medical imaging system is corrected according to the preset correction protocol. For example, the image result of the medical imaging system does not meet the preset conditions, for example, the image result of the medical imaging system may have motion artifacts. According to the above, taking the selected compensation difference boundary as a as an example, the reader only receives the first zero point signal to reset, then the first zero point signal is either a false zero signal between a and e, or it may be a real zero point signal corresponding to e. If subsequent medical images have motion artifacts, it can be determined that the zero point signal received by the reader for the first time is a false zero point signal between a and e. At this time, the operator corrects the CT according to the preset correction protocol.

[0070] Based on the above-described method for compensating rotational errors in a medical imaging system, this embodiment further provides a storage medium having a readable and writable program stored thereon. When executed, the program implements the above-described method for compensating rotational errors in a medical imaging system. Specifically, the method for compensating rotational errors in a medical imaging system provided by the present invention can be compiled into a program or software and stored on the storage medium. In actual use, the program stored on the storage medium is utilized to execute each step of the method for compensating rotational errors in a medical imaging system. The storage medium can be integrated into a processor of the medical imaging system or independently provided in other hardware.

[0071] Based on the same inventive concept as the method for compensating for rotational errors in the medical imaging system, one embodiment of the present invention further provides a medical imaging system, which may be a computed tomography (CT) system or a positron emission tomography (PET-CT) system. The medical imaging system includes a magnetic scale, a rotating frame, a reader, and a processor (a first processor). The magnetic scale is coaxially fixed to the rotating frame, the reader is fixed relative to the center of the rotating frame, and the first processor is configured to execute:

[0072] At least two different compensating interpolation boundaries are configured on the physical circumference segment of the magnetic scale 60; the compensating interpolation boundaries and the virtual notch segment 601 of the magnetic scale 60 are arranged in sequence along the rotation direction of the magnetic scale 60, and one of the compensating interpolation boundaries is selected according to the motion state of the magnetic scale 60;

[0073] The selected compensation interpolation boundary is limited to be located on the upstream side of the rotation direction of the magnetic scale 60 and the factory interpolation boundary of the magnetic scale 60 is located on the downstream side of the rotation direction of the magnetic scale 60, thereby defining a transition section of the magnetic scale 60;

[0074] Interpolating and compensating the transition section according to the kinematic function established by the magnetic scale 60 and the rotation direction of the magnetic scale 60;

[0075] Among them, the compensation interpolation boundary and the factory interpolation boundary f are located on both sides of the virtual gap segment 601 of the magnetic scale 60, and the rotation direction of the magnetic scale 60 is the direction defined by the compensation interpolation boundary, the virtual gap segment 601 and the factory interpolation boundary f in sequence.

[0076] Furthermore, the medical imaging system further includes a rotating motor, the rotating gantry 10 is configured as a rotor 70 of the rotating motor, and the read head is mounted on a stator of the rotating motor.

[0077] Furthermore, the compensation interpolation boundary selected when the magnetic scale 60 performs uniform circular motion is larger than the compensation interpolation boundary selected when the magnetic scale 60 performs variable speed circular motion.

[0078] Furthermore, all the compensation interpolation boundaries are located within a 1 / 4 circumference range of the virtual notch segment 601 .

[0079] Furthermore, the first processor is further configured to execute:

[0080] The factory interpolation boundary of the magnetic scale 60 is limited to be located on the upstream side of the rotation direction of the magnetic scale 60 and the selected compensation interpolation boundary is located on the downstream side of the rotation direction of the magnetic scale 60, thereby defining the sampling section of the magnetic scale 60;

[0081] A kinematic function of the magnetic scale is established according to each angular scale in the sampling segment and the sampling time corresponding to the angular scale.

[0082] Furthermore, the medical imaging system further includes a second processor linked to the first processor, and the second processor is configured to execute:

[0083] Analyze the zero point signal to determine the expected zero point boundary on the magnetic scale 60 corresponding to the zero point signal;

[0084] When the expected zero point boundary is less than or equal to the selected compensation interpolation boundary and greater than the factory interpolation boundary f, the reading head is maintained in a counting working state for the sensor signal of the magnetic scale;

[0085] When the expected zero point boundary is greater than the selected compensation interpolation boundary, the read head is controlled to reset only once, and the sensing signal of the magnetic scale 60 is detected and counted again.

[0086] Furthermore, the second processor is further configured to execute:

[0087] When the second processor detects that the image result of the medical imaging system does not meet a preset condition, it determines that the expected zero point boundary is between the compensated interpolation boundary and the true zero point boundary e, and calibrates the medical imaging system according to a preset calibration protocol. For example, the image result of the medical imaging system not meeting the preset condition includes the image result of the medical imaging system exhibiting motion artifacts.

[0088] In this embodiment, the first processor and the second processor may be independently provided or integrated into one, for example, within the electronic computer of the CT system. It should be noted that those skilled in the art can further understand the details of the first processor and the second processor in the medical imaging system of this embodiment based on the description of the compensation method in the specification, and will not be further described here.

[0089] In summary, in the medical imaging system and its rotation error compensation method and storage medium provided by the present invention, the compensation method includes: configuring at least two different compensation interpolation boundaries on a physical circumferential segment of a magnetic scale installed on a rotating frame, and selecting one of the compensation interpolation boundaries according to the motion state of the magnetic scale; limiting the selected compensation interpolation boundary to be located on the upstream side of the rotation direction of the magnetic scale and the factory interpolation boundary of the magnetic scale to be located on the downstream side of the rotation direction of the magnetic scale, thereby defining the transition section of the magnetic scale; interpolating and compensating the transition section according to the kinematic function established for the magnetic scale and in accordance with the rotation direction of the magnetic scale; wherein the compensation interpolation boundary and the factory interpolation boundary are located on both sides of the virtual notch segment of the magnetic scale, and the rotation direction of the magnetic scale is the direction defined in sequence by the compensation interpolation boundary, the virtual notch segment, and the factory interpolation boundary. Compared to prior art approaches that simply set a fixed boundary value without considering the actual motion state of the magnetic scale, the compensation method of the present invention sets at least two different compensation interpolation boundaries. An appropriate compensation interpolation boundary can be selected based on the different motion states of the magnetic scale. The selected compensation interpolation boundary and the factory interpolation boundary are then used to define the transition section of the magnetic scale. This means that different transition sections are determined based on the different motion states of the magnetic scale. The interpolation compensation transition section is then predicted based on a kinematic function, ensuring that the reader continues to count properly when transitioning through a virtual gap section of the magnetic scale and reducing the probability of the reader misreading false zero signals during the interpolation process, thereby ensuring the quality of medical images. Furthermore, the compensation interpolation boundary selected when the magnetic scale is in uniform circular motion is larger than the compensation interpolation boundary selected when the magnetic scale is in variable speed circular motion. Thus, when the magnetic scale is in uniform circular motion, the defined transition section is smaller, the probability of a false zero signal is also lower, and even if the reader misreads a false zero signal, data loss from the interpolation compensation is minimal.

[0090] The above description is only a description of the preferred embodiment of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure are within the scope of protection of the technical solution of the present invention.

Claims

1. A method for compensating rotational errors in a medical imaging system, characterized in that: include: At least two different compensation interpolation boundaries are configured on a physical circumferential segment of a magnetic scale (60) mounted on a rotating frame (10), and one of the compensation interpolation boundaries is selected according to the motion state of the magnetic scale (60); wherein the compensation interpolation boundary (b) selected when the magnetic scale (60) performs uniform circular motion is larger than the compensation interpolation boundary (a) selected when the magnetic scale (60) performs variable speed circular motion; The selected compensation interpolation boundary is limited to be located on the upstream side of the rotation direction of the magnetic scale (60) and the factory interpolation boundary (f) of the magnetic scale (60) is located on the downstream side of the rotation direction of the magnetic scale (60), thereby defining a transition section of the magnetic scale (60); interpolating and compensating the transition section according to a kinematic function established by the magnetic scale (60) and in accordance with the rotation direction of the magnetic scale (60); The compensation interpolation boundary and the factory interpolation boundary (f) are located on both sides of the virtual notch segment (601) of the magnetic scale (60); the rotation direction of the magnetic scale (60) is a direction defined by the compensation interpolation boundary, the virtual notch segment (601) and the factory interpolation boundary (f) in sequence; a real zero point boundary (e) is provided on a physical circumferential segment of the magnetic scale (60); and the real zero point boundary (e) is located between the virtual notch segment (601) and the factory interpolation boundary (f).

2. The method for compensating rotational errors of a medical imaging system according to claim 1, wherein the step of establishing the kinematic function of the magnetic scale (60) comprises: The factory interpolation boundary (f) of the magnetic scale (60) is limited to be located on the upstream side of the rotation direction of the magnetic scale (60), and the selected compensation interpolation boundary is located on the downstream side of the rotation direction of the magnetic scale (60), thereby defining the sampling section of the magnetic scale (60); A kinematic function of the magnetic scale (60) is established based on each angular scale in the sampling section and the sampling time corresponding to the angular scale.

3. The method for compensating rotation error of a medical imaging system according to claim 1, wherein: All of the compensation interpolation boundaries are located within a 1 / 4 circumference range of the virtual notch segment (601).

4. The method for compensating rotation error of a medical imaging system according to claim 1, wherein: The compensation method further comprises: Analyzing the zero point signal to determine an expected zero point boundary on the magnetic scale (60) corresponding to the zero point signal; When the expected zero point boundary is less than or equal to the selected compensation interpolation boundary and greater than the factory interpolation boundary (f), the reading head is maintained in a counting working state for the sensing signal of the magnetic scale (60); When the expected zero point boundary is greater than the selected compensation interpolation boundary, the read head is controlled to reset and reset only once, and the sensing signal of the magnetic scale (60) is detected and counted again.

5. The method for compensating rotation error of a medical imaging system according to claim 4, wherein: The compensation method further comprises: If the image result of the medical imaging system does not meet the preset conditions, it is determined that the expected zero point boundary is between the compensated interpolation boundary and the real zero point boundary (e) in the transition section, and the medical imaging system is calibrated according to a preset correction protocol.

6. The method for compensating rotation error of a medical imaging system according to claim 5, characterized in that: The image result of the medical imaging system does not meet the preset condition, which includes that the image result of the medical imaging system has motion artifacts.

7. A medical imaging system, characterized in that: The medical imaging system comprises a magnetic scale (60), a rotating gantry (10), a reader, and a processor, wherein the magnetic scale (60) is coaxially fixed to the rotating gantry (10), the reader is fixed relative to the center position of the rotating gantry (10), and the processor is configured to execute: At least two different compensation interpolation boundaries are configured on a physical circumferential segment of the magnetic scale (60), and one of the compensation interpolation boundaries is selected according to the motion state of the magnetic scale (60); wherein the compensation interpolation boundary (b) selected when the magnetic scale (60) performs uniform circular motion is larger than the compensation interpolation boundary (a) selected when the magnetic scale (60) performs variable speed circular motion; The selected compensation interpolation boundary is limited to be located on the upstream side of the rotation direction of the magnetic scale (60) and the factory interpolation boundary (f) of the magnetic scale (60) is located on the downstream side of the rotation direction of the magnetic scale (60), thereby defining a transition section of the magnetic scale (60); interpolating and compensating the transition section according to a kinematic function established by the magnetic scale (60) and in accordance with the rotation direction of the magnetic scale (60); The compensation interpolation boundary and the factory interpolation boundary (f) are located on both sides of the virtual notch segment (601) of the magnetic scale (60); the rotation direction of the magnetic scale (60) is a direction defined by the compensation interpolation boundary, the virtual notch segment (601) and the factory interpolation boundary (f) in sequence; a real zero point boundary (e) is provided on a physical circumferential segment of the magnetic scale (60); and the real zero point boundary (e) is located between the virtual notch segment (601) and the factory interpolation boundary (f).

8. The medical imaging system according to claim 7, wherein: The medical imaging system further includes a rotary motor, the rotary gantry is configured as a rotor of the rotary motor, and the read head is mounted on a stator of the rotary motor.

9. A storage medium having a readable and writable program stored thereon, characterized in that: When the program is executed, the method for compensating for rotation error of a medical imaging system according to any one of claims 1 to 6 can be implemented.

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