A method and measurement assembly for measuring MR-linac registration errors
By installing a positioning base and a scanning base on the MR-linac treatment bed, and using CT and MRI imaging to record the image displacement coordinate difference, the delay problem of MR-linac registration error detection is solved, enabling rapid and accurate registration error detection and improving the precision of treatment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANDONG NORMAL UNIV
- Filing Date
- 2023-04-03
- Publication Date
- 2026-07-21
AI Technical Summary
In existing technologies, the multimodal image registration accuracy of MR-linac cannot be detected in real time during treatment, leading to problems such as insufficient tumor dose and excessive dose to high-risk organs.
A method for measuring MR-linac registration error is provided. By installing a positioning base and a scanning base on a CT and MR-linac treatment bed, and using two CT scans and MRI imaging, the image displacement coordinate difference is recorded, and the automatic registration error is calculated to achieve rapid detection of registration accuracy.
It improves the accuracy of MR-linac image registration and positioning, reduces errors during treatment, and ensures the reliability of treatment results.
Smart Images
Figure CN116392099B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of radiotherapy device technology, and in particular to a method and measuring components for measuring MR-linac registration error. Background Technology
[0002] The MR-linac (Magnetic Resonance Imaging Guided Medical Linear Accelerator) is a key medical device in magnetic resonance-guided radiotherapy (MRgRT), primarily composed of an MRI (Magnetic Resonance Imaging) system and a radiotherapy system. The MR-linac can perform MRI scans before irradiation therapy to provide high-quality, real-time MRI guidance during treatment, assessing and correcting anatomical changes in the patient during or after treatment. Before MR-linac-guided radiotherapy, multimodal image registration is required. This registration primarily involves aligning the pre-treatment MRI with simulated localization CT images. This step is completed before each treatment fraction in the MR-linac's adaptive planning system. Registration primarily uses the CT image as the reference image and the MRI as a floating image. After registration, the alignment distance between the CT and MR images is displayed for precise localization. The MR-linac treatment bed is identical to the CT bed. In clinical applications of the MR-linac, rigid body registration is the primary method used. However, the accuracy of automatic registration cannot be known during treatment, and poor image registration may lead to insufficient tumor dosage and excessive dosage to high-risk organs. Currently, the accuracy of registration can only be known when MR-linac is checked monthly, which obviously has a large delay. Therefore, there is an urgent need to propose a method that can quickly detect the accuracy of registration in daily work. Summary of the Invention
[0003] The purpose of this invention is to solve the above-mentioned technical problems and provide a method and component for measuring MR-linac registration error. This method and component can quickly and effectively detect whether the automatic registration of MR-linac with MR-CT is truly accurate. It can be quickly tested before the start of each day's treatment to meet daily needs.
[0004] To achieve the above objectives, the present invention provides the following solution: The present invention discloses a method for measuring MR-linac registration error, comprising the following steps: S1. Position the scanning reference object with positioning marks at a preset position on the CT medical bed and perform CT imaging. Then, position the scanning reference object at the position corresponding to the preset position on the MR-linac medical bed and perform online MRI. Subsequently, with CT as the reference image and MRI as the floating image, perform automatic registration in the adaptive planning system of the MR-linac medical bed and record the image displacement coordinates (X1, Y1, Z1) of the positioning marks. S2. Change the preset position of the scanning reference object on the CT medical bed, perform online MRI again, and use the CT in step S1 as the reference image and the newly scanned MRI as the floating image to automatically register in the adaptive planning system of the MR-linac medical bed to obtain the image shift coordinates (X2, Y2, Z2). S3. Obtain the actual displacement difference (ΔX´, ΔY´, ΔZ´) based on the difference in the preset position change before and after the positioning mark. Subtract the actual displacement difference (ΔX´, ΔY´, ΔZ´) from the image shift coordinate (X2, Y2, Z2) to obtain the automatic registration error.
[0005] Preferably, in step S1, a medical bed clip is first installed on the CT medical bed, with the medical bed clip corresponding to a certain scale value on both sides of the CT medical bed. Then, a positioning and measuring base capable of calibrating the coordinates of the object is installed on the medical bed clip. A preset position is selected on the positioning and measuring area. Subsequently, the scanning reference object is placed on the preset position of the positioning and measuring base for CT scanning. Then, a medical bed clip is installed on the MR-linac medical bed, with the scale value on the MR-linac medical bed corresponding to the medical bed clip being the same as the scale value corresponding to the medical bed clip on the CT medical bed. The original relative positions of the scanning reference object and the positioning and measuring base are maintained, and online MRI is performed.
[0006] Preferably, in step S2, the positioning base is installed onto the medical bed clip on the CT medical bed in step S1, the position of the scanning reference object on the measuring base is changed, a CT scan is performed, the position of the scanning reference object on the measuring base is maintained, and the scanning reference object is installed onto the medical bed clip on the MR-linac medical bed in step S1 for online MRI.
[0007] A measurement component for MR-linac registration error is also disclosed, comprising a scanning substrate and a non-metallic positioning base. The scanning substrate has a transparent scanning area, and an opaque positioning mark is located at the center of the transparent scanning area. The top surface of the positioning base has a positioning measurement area for placing the scanning substrate. The positioning measurement area has positioning points that can mark the coordinates of the positioning mark. The positioning points are evenly distributed in four quadrants with the crosshair of the positioning measurement area as the rectangular coordinate system. The bottom surface of the positioning base has a strip groove for locking onto a medical bed clip. The strip groove has a positioning hole for the positioning head on the medical bed clip to be inserted. The medical bed clip is perpendicular to the bed entry direction, and the extension direction of the strip groove is perpendicular to and parallel to the two lines of the crosshair, respectively.
[0008] Preferably, the positioning mark is a cross mark set on the top surface of the transparent scanning area.
[0009] Preferably, the positioning points are measuring holes arranged in a matrix at equal intervals, and the bottom surface of the transparent scanning area is provided with a connector for insertion into the measuring holes. The connector is distributed in at least two quadrants with the cross mark as the rectangular coordinate system.
[0010] Preferably, the scanning substrate is a transparent square box filled with transparent gel.
[0011] Preferably, both the transparent square box and the positioning base are made of plastic.
[0012] Preferably, the positioning base is a rectangular body, and the strip groove is parallel to the length direction of the rectangular body.
[0013] Preferably, the usage process includes: S1. Install a medical bed clip on the CT medical bed, with the clip corresponding to a certain scale value on both sides of the CT medical bed. Secure the strip-shaped slot of the positioning base onto the medical bed clip, and insert the positioning hole into the positioning head. Select a preset position on the positioning measurement area, place the scanning substrate at the selected preset position, adjust the position of the CT medical bed so that the laser lamp is aligned with the crosshair, and generate a CT image of the scanning substrate. Then, install a medical bed clip on the MR-linac medical bed, with the scale value on the MR-linac medical bed corresponding to the medical bed clip on the CT medical bed being consistent with the scale value corresponding to the medical bed clip on the CT medical bed. Install the positioning base on the medical bed clip on the MR-linac medical bed, keeping the relative position of the scanning substrate and the positioning base unchanged, and perform online MRI. After scanning, in the adaptive planning system of the MR-linac medical bed, use CT as the reference image and MRI as the floating image for automatic registration, and record the image shift distance (X1, Y1, Z1) of the crosshair. S2. Change the position of the scanning substrate on the positioning base, rescan the MRI and register it, and record the image displacement distance (X2, Y2, Z2); S3. Obtain the actual displacement difference (ΔX´, ΔY´, ΔZ´) based on the difference between the two preset position changes of the cross mark. Subtract the image coordinate difference (X2, Y2, Z2) from the actual displacement difference (ΔX´, ΔY´, ΔZ´) to obtain the automatic registration error.
[0014] The present invention achieves the following technical effects compared to the prior art: 1. In the method for measuring MR-linac registration error of the present invention, automatic registration is performed by performing two CT scans and MRI irradiations before and after the position of the scanning reference object changes, and the resulting image coordinate difference is compared with the actual displacement difference of the scanning reference object after the position change to obtain the automatic registration error. At the same time, by keeping the position of the scanning reference object consistent during the two imaging processes of CT scan and MRI irradiation, the accuracy of automatic registration of CT-MR images can be improved to a certain extent.
[0015] 2. In the method for measuring the registration error of MR-linac in this invention, the medical bed clips that come with the CT treatment bed and the MR-linac treatment bed are used for positioning. Compared with positioning by using the human body as a reference, this method can greatly improve the accuracy and portability of positioning. Currently, for safety reasons, only CT imaging rooms have laser lights to assist in human positioning, while MR-linac treatment rooms do not. Therefore, if positioning is done by using the markings on the human body surface and the scale on the bed board, it can only be done visually in MR-linac clinical treatment, which will bring great uncertainty.
[0016] 3. In the MR-linac registration error measurement component of the present invention, the measurement is mainly performed by the cooperation of a positioning base and a scanning substrate. The positioning base can be locked onto the medical bed clip using its bottom strip groove. As long as the scale on the treatment bed where the medical bed clip is located is consistent, the position of the positioning base on the CT medical bed and the MR-linac treatment bed will be highly consistent, ensuring the accuracy of positioning. Moreover, each registration only requires changing the position of the scanning substrate on the positioning base, and the position of the positioning base does not need to be changed. This further ensures that the position of the positioning base on the CT medical bed and the MR-linac treatment bed is consistent, thus improving the measurement accuracy. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a schematic diagram of the three-dimensional structure of the measuring component; Figure 2 A top view of the top surface of the measurement component; Figure 3 A three-dimensional structural diagram of the top surface of the positioning base; Figure 4 A three-dimensional structural diagram of the bottom surface of the positioning base; Figure 5 A top view of the top surface of the positioning base; Figure 6 A bottom view of the base surface; Figure 7 This is a schematic diagram of the three-dimensional structure of the top surface of the scanning substrate; Figure 8 This is a schematic diagram of the three-dimensional structure of the bottom surface of the scanned substrate; Figure 9 This is a top view of the top surface of the scanned substrate.
[0019] Explanation of reference numerals in the attached drawings: 1. Scanning substrate; 2. Positioning base; 3. Cross mark; 4. Strip groove; 5. Positioning hole; 6. Measuring hole; 7. Connector. Detailed Implementation
[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only one embodiment of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0021] Example 1 This embodiment provides a method for measuring MR-linac registration error, such as... Figures 1 to 9 As shown, it includes the following steps: S1. Position the scanning reference object with positioning marks at the preset position on the CT medical bed and perform CT imaging. Then, position the scanning reference object at the position corresponding to the preset position on the MR-linac medical bed and perform online MRI. Subsequently, with CT as the reference image and MRI as the floating image, perform automatic registration in the adaptive planning system of the MR-linac medical bed and record the image displacement coordinates (X1, Y1, Z1) of the positioning marks, that is, the alignment distance between the CT image and the MR image. S2. Change the preset position of the scanning reference object on the CT medical bed, perform online MRI again, and use the CT in step S1 as the reference image and the newly scanned MRI as the floating image to perform automatic registration again in the adaptive planning system of the MR-linac medical bed to obtain the image shift coordinates (X2, Y2, Z2), that is, the alignment distance between the new MR image and the original CT image. S3. Obtain the actual displacement difference (ΔX´, ΔY´, ΔZ´) based on the difference in the preset position change before and after the positioning mark. Subtract the actual displacement difference (ΔX´, ΔY´, ΔZ´) from the image shift coordinates (X2, Y2, Z2) in step S2 to obtain the automatic registration error.
[0022] The Y direction represents the head-to-toe direction, the X direction represents the left-right direction of the human body, and the Z direction represents the front-back direction of the human body. The error in these three directions can then be measured.
[0023] Preferably, the image shift coordinates (X1, Y1, Z1) in step S1 can be used as the base point. Then, in step S2, the position on the scanning reference can be changed multiple times, and MRI scans can be performed for registration. Each registration is based on the CT image in S1. The above method is repeated multiple times to verify the error at different positions, resulting in multiple sets of image shift coordinates (X1, Y1, Z1). a Y a Z a ), and then each group's (X) a Y a Z aSubtracting the actual displacement difference (ΔX´, ΔY´, ΔZ´) for each step, we can obtain the error of automatic registration. The actual displacement difference is based on the scanning reference object (positioning mark) in step S1.
[0024] Positioning markers can be dotted, polygonal, or cross-shaped, with cross-shaped markers being preferred. Cross-shaped markers ensure precise alignment of the laser head on the CT treatment bed. By aligning the cross-shaped laser beam emitted from the laser head with the cross-shaped marker, alignment is more accurate. Figure 1 , Figure 2 , Figure 7 Diagram and Figure 9 The cross mark 3 in the middle.
[0025] To improve the accuracy and convenience of positioning the scanning reference object, in this embodiment, in step S1, a medical bed clip is first installed on the CT medical bed, with the medical bed clip corresponding to a certain scale value on both sides of the CT medical bed. Then, a measuring base is installed on the medical bed clip, and the measuring base has a positioning measurement area that can calibrate the coordinates of the placed object. A preset position is selected in the positioning measurement area, and then the scanning reference object is placed at the preset position of the measuring base for CT scanning. Then, a medical bed clip is installed on the MR-linac medical bed, and the scale value on the MR-linac medical bed corresponding to the medical bed clip is the same as the scale value corresponding to the medical bed clip on the CT medical bed, maintaining the original relative position of the scanning reference object and the measuring base for online MRI.
[0026] Furthermore, in this embodiment, as Figures 1 to 9 As shown, in step S2, the measurement mount is installed onto the medical bed clip on the CT medical bed in step S1, the position of the scanning reference on the measurement mount is changed, and a CT scan is performed. The scanning reference is kept in the position of the measurement mount, and the scanning reference is installed onto the medical bed clip on the MR-linac medical bed in step S1 for online MRI.
[0027] Example 2 This embodiment provides a measurement component for MR-linac registration error, such as... Figures 1 to 9As shown, the system includes a scanning substrate 1 capable of resonant imaging and a positioning base 2 made of non-metallic material. The scanning substrate 1 can serve as a scanning reference in Embodiment 1, while the positioning base 2 can serve as a mounting base for measurement in Embodiment 1. The scanning substrate 1 has a transparent scanning area, with an opaque positioning mark at the center of the transparent scanning area. The scanning substrate 1 can be entirely transparent or partially transparent. The top surface of the positioning base 2 has a positioning measurement area for placing the scanning substrate 1. The positioning measurement area has positioning points that can mark the coordinates of the positioning mark. The positioning points are evenly distributed in four quadrants with the crosshair of the positioning measurement area as the rectangular coordinate system. The bottom surface of the positioning base 2 has a strip-shaped slot 4, which can be used to lock onto the medical bed clip. The strip-shaped slot 4 has a positioning hole 5, which can be inserted into the positioning head of the medical bed clip. Typically, the medical bed clip has two positioning heads, hence there are two positioning holes 5. After the medical bed retainer is installed on the treatment bed, it is perpendicular to the direction of entry into the bed. The extension direction of the strip groove 4 is perpendicular to and parallel to the two lines of the cross center line, respectively.
[0028] In this embodiment, as Figures 1 to 9 As shown, the positioning mark is a cross mark 3 set on the top surface of the transparent scanning area.
[0029] To improve the positioning stability between the scanning substrate 1 and the positioning base 2, the position of the crosshair 3 is kept unchanged during the measurement process. In this embodiment, as shown... Figures 1 to 9 As shown, the positioning points are measurement holes 6 arranged in a matrix at equal intervals. A connector 7 is provided on the bottom surface of the transparent scanning area. The connector 7 is used to insert into the measurement holes 6. The connectors 7 are distributed in at least two quadrants with the crosshair 3 as the Cartesian coordinate system, achieving two-point positioning. Preferably, four connectors 7 can be provided, evenly distributed in the four quadrants with the crosshair 3 as the Cartesian coordinate system, i.e., the crosshair 3 is the center of the four connectors 7. A total of thirty-six measurement holes 6 are provided, with nine measurement holes 6 in each of the four quadrants formed by the crosshair center lines of the transparent scanning area. Of course, the above values are only preferred options; other values can be set as long as the requirements are met, such as six connectors 7, forty-eight measurement holes 6, and twelve measurement holes 6 in each quadrant.
[0030] Furthermore, in this embodiment, as Figures 1 to 9 As shown, since the MR-linac treatment bed and the CT treatment bed are exactly the same, with scale points spaced 4cm apart on both sides, the horizontal and vertical spacing of the measuring holes 6 is set to 1cm. The horizontal and vertical spacing of the four connectors 7 is also 1cm, which allows the scanning base 1 to change position on the positioning base 2 with a fixed step size and direction.
[0031] In this embodiment, as Figures 1 to 9As shown, the scanning substrate 1 is a transparent square box filled with transparent gel. The transparent square box is filled with transparent gel so that it can be used for T2 sequence magnetic resonance imaging. It is set to be transparent in order to reduce imaging interference and ensure the clarity of the cross mark 3 in CT and magnetic resonance images.
[0032] In this embodiment, as Figures 1 to 9 As shown, both the transparent square box and the positioning base 2 are made of plastic.
[0033] In this embodiment, as Figures 1 to 9 As shown, the positioning base 2 is a rectangular body, and the strip slot 4 is parallel to the length direction of the rectangular body.
[0034] In this embodiment, as Figures 1 to 9 As shown, the specific usage process of this measurement component includes: S1. Install the medical bed clip on the CT medical bed. The medical bed clip corresponds to a certain scale value on both sides of the CT medical bed. Attach the strip groove 4 of the positioning base 2 to the medical bed clip and insert the positioning hole 5 into the positioning head. Select a preset position on the positioning measurement area, preferably the middle position. Place the scanning substrate 1 at the selected preset position, adjust the position of the CT medical bed so that the laser lamp coincides with the crosshair 3, and generate a CT image of the scanning substrate 1. Then, install the medical bed clip on the MR-linac medical bed. The scale value of the medical bed clip on the MR-linac medical bed is consistent with the scale value of the medical bed clip on the CT medical bed. Install the positioning base 2 on the medical bed clip on the MR-linac medical bed, keeping the relative position of the scanning substrate 1 and the positioning base 2 unchanged, and perform online MRI. After the scan is completed, perform automatic registration in the adaptive planning system of the MR-linac medical bed with CT as the reference image and MRI as the floating image. Select the rigid registration mode. After the registration is completed, perform a manual check. After confirming that the registration result is accurate, record the image displacement distance (X1, Y1, Z1) of the crosshair 3. The manual check is to check whether the registration is accurate. The specific process is to manually move the MRI to achieve the best registration effect. The standard for verifying the best effect is visual inspection by an experienced radiation oncologist.
[0035] S2. Change the position of the scanning substrate 1 on the positioning base 2, rescan the MRI and perform registration. After registration is completed, perform a manual check. After confirming that the registration result is accurate, record the image displacement distance (X2, Y2, Z2).
[0036] S3. The actual displacement difference (ΔX´, ΔY´, ΔZ´) is obtained based on the difference between the two preset position changes before and after the crosshair mark 3. Since the displacement direction and distance of the substrate 1 are determined for each scan, the exact error distance can be known before registration. The image coordinate difference (X2, Y2, Z2) is subtracted from the actual displacement difference (ΔX´, ΔY´, ΔZ´) to obtain the automatic registration error. Preferably, the position of the scanning substrate 1 on the positioning base 2 can be changed multiple times, with the direction and distance of movement of the scanning substrate 1 changed each time. The MRI scan is then registered with the CT scan in step S1. The registration error of the scanning substrate 1 at different positions is then accurately measured.
[0037] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.
Claims
1. A method for measuring MR-linac registration error, characterized in that, Includes the following steps: S1. Position the scanning reference object with positioning marks at a preset position on the CT medical bed and perform CT imaging. Then, position the scanning reference object at the position corresponding to the preset position on the MR-linac medical bed and perform online MRI. Subsequently, with CT as the reference image and MRI as the floating image, perform automatic registration in the adaptive planning system of the MR-linac medical bed and record the image displacement coordinates (X1, Y1, Z1) of the positioning marks. S2. Change the preset position of the scanning reference object on the CT medical bed, perform online MRI again, and use the CT in step S1 as the reference image and the newly scanned MRI as the floating image to automatically register in the adaptive planning system of the MR-linac medical bed to obtain the image shift coordinates (X2, Y2, Z2). S3. Obtain the actual displacement difference (ΔX´, ΔY´, ΔZ´) based on the difference in the preset position change before and after the positioning mark. Subtract the actual displacement difference (ΔX´, ΔY´, ΔZ´) from the image shift coordinate (X2, Y2, Z2) to obtain the automatic registration error.
2. The method for measuring MR-linac registration error according to claim 1, characterized in that, In step S1, a medical bed clip is first installed on the CT medical bed, with the clip corresponding to a certain scale value on both sides of the CT medical bed. Then, a positioning and measuring base capable of calibrating the coordinates of the object is installed on the medical bed clip. A preset position is selected on the positioning and measuring area. Subsequently, the scanning reference object is placed on the preset position of the positioning and measuring base for CT scanning. Then, a medical bed clip is installed on the MR-linac medical bed, with the scale value on the MR-linac medical bed corresponding to the medical bed clip being the same as the scale value corresponding to the medical bed clip on the CT medical bed. The original relative positions of the scanning reference object and the positioning and measuring base are maintained, and online MRI is performed.
3. The method for measuring MR-linac registration error according to claim 2, characterized in that, In step S2, the positioning base is installed onto the medical bed clip on the CT medical bed in step S1, the position of the scanning reference object on the measuring base is changed, and a CT scan is performed. The position of the scanning reference object on the measuring base is maintained at this time, and the scanning reference object is installed onto the medical bed clip on the MR-linac medical bed in step S1 for online MRI.
4. A measurement component for MR-linac registration error, characterized in that, The device includes a scanning substrate and a positioning base made of non-metallic materials. The scanning substrate has a transparent scanning area with an opaque positioning mark at its center. The top surface of the positioning base has a positioning measurement area for placing the scanning substrate. The positioning measurement area has positioning points that can mark the coordinates of the positioning mark. The positioning points are evenly distributed in four quadrants with the crosshair of the positioning measurement area as the Cartesian coordinate system. The bottom surface of the positioning base has a strip-shaped groove for locking onto a medical bed clip. The strip-shaped groove has a positioning hole for the positioning head on the medical bed clip to be inserted. The medical bed clip is perpendicular to the bed entry direction, and the extension direction of the strip-shaped groove is perpendicular to and parallel to the two lines of the crosshair, respectively.
5. The MR-linac registration error measurement component according to claim 4, characterized in that, The positioning mark is a cross mark set on the top surface of the transparent scanning area.
6. The MR-linac registration error measurement component according to claim 5, characterized in that, The positioning points are measurement holes arranged in a matrix at equal intervals. The bottom surface of the transparent scanning area is provided with a connector for insertion into the measurement holes. The connector is distributed in at least two quadrants with the cross mark as the rectangular coordinate system.
7. The MR-linac registration error measurement component according to claim 6, characterized in that, The scanning substrate is a transparent square box filled with transparent gel.
8. The MR-linac registration error measurement component according to claim 7, characterized in that, Both the transparent square box and the positioning base are made of plastic.
9. The MR-linac registration error measurement component according to claim 6, characterized in that, The positioning base is a rectangular body, and the strip slot is parallel to the length direction of the rectangular body.
10. A measurement component for MR-linac registration error according to claim 9, characterized in that, The usage process includes: S1. Install a medical bed clip on the CT medical bed, with the clip corresponding to a certain scale value on both sides of the CT medical bed. Secure the strip-shaped slot of the positioning base onto the medical bed clip, and insert the positioning hole into the positioning head. Select a preset position on the positioning measurement area, place the scanning substrate at the selected preset position, adjust the position of the CT medical bed so that the laser lamp is aligned with the crosshair, and generate a CT image of the scanning substrate. Then, install a medical bed clip on the MR-linac medical bed, with the scale value on the MR-linac medical bed corresponding to the medical bed clip on the CT medical bed being consistent with the scale value corresponding to the medical bed clip on the CT medical bed. Install the positioning base on the medical bed clip on the MR-linac medical bed, keeping the relative position of the scanning substrate and the positioning base unchanged, and perform online MRI. After scanning, in the adaptive planning system of the MR-linac medical bed, use CT as the reference image and MRI as the floating image for automatic registration, and record the image shift distance (X1, Y1, Z1) of the crosshair. S2. Change the position of the scanning substrate on the positioning base, rescan the MRI and register it, and record the image displacement distance (X2, Y2, Z2); S3. Obtain the actual displacement difference (ΔX´, ΔY´, ΔZ´) based on the difference between the two preset position changes of the cross mark. Subtract the image coordinate difference (X2, Y2, Z2) from the actual displacement difference (ΔX´, ΔY´, ΔZ´) to obtain the automatic registration error.