Medical phantom, and method and system for detecting equipment accuracy based on medical phantom

Abstract

The present invention discloses a medical phantom, as well as a method and a system for detecting the accuracy of a device based on the medical phantom, relating to the technical field of device detection. The main purpose is to solve the problems of poor accuracy and low efficiency in the existing manual accuracy detection of tomographic scanning devices. The medical phantom includes: a main phantom, and a set of metal parts arranged on the side wall of the main phantom; wherein, the set of metal parts includes at least a pair of main metal parts, and a pair of the main metal parts are symmetrically arranged with respect to the central cross-section of the main phantom; after the main phantom is scanned in a tomographic scanning system, the main projection position data of the main metal parts are obtained, so as to perform the device accuracy detection of the tomographic scanning system based on the main projection position data.

Description

Technical Field

[0001] The present invention relates to the technical field of equipment detection, and particularly to a medical phantom and a method and system for detecting the accuracy of equipment based on the medical phantom. Background Art

[0002] With the rapid development of medical technology, the accuracy requirements for medical equipment have gradually increased to better match the development of medical technology. Among them, a medical linear accelerator (abbreviated as accelerator) is a medical device used for radiotherapy of tumors and other lesions. The geometric accuracy of the accelerator directly affects the treatment effect. Therefore, during use, it is necessary to ensure the accuracy of radiotherapy of the accelerator.

[0003] Currently, the existing detection of the geometric accuracy based on the accelerator usually relies on manually using auxiliary calibration tools such as coordinate paper, rulers, front pointers, and detection plates for manual accuracy detection, and visually observing the laser lamp to position the auxiliary calibration tools and using measuring tools to measure errors. However, manual accuracy detection inevitably introduces human errors, has poor repeatability and inaccurate detection accuracy. Moreover, there are many items that need to be detected for geometric accuracy in the accelerator, and multiple manual operations are time-consuming and laborious, and will bring additional radiation hazards to the operators. Summary of the Invention

[0004] In view of this, the present invention provides a medical phantom and a method and system for detecting the accuracy of equipment based on the medical phantom, mainly aiming to solve the problems of poor accuracy and low efficiency in the existing manual detection of the accuracy of tomographic scanning equipment.

[0005] According to one aspect of the present invention, a medical phantom is provided, which is characterized by including: a main phantom, and a group of metal parts arranged on the side wall of the main phantom;

[0006] Wherein, the group of metal parts includes at least a pair of main metal parts, and a pair of the main metal parts are symmetrically arranged with respect to the central cross-section of the main phantom;

[0007] After the main phantom is scanned in a tomographic scanning system, the main projection position data of the main metal parts are obtained, and the equipment accuracy of the tomographic scanning system is detected based on the main projection position data.

[0008] Further, the group of metal parts further includes at least a pair of auxiliary metal parts, and each pair of the auxiliary metal parts are symmetrically arranged with respect to the central cross-section of the main phantom;

[0009] Wherein, after the main phantom is scanned in the tomographic scanning system, the auxiliary projection position data of the auxiliary metal parts are obtained, and the relative position of the main phantom in the tomographic scanning system is corrected based on the auxiliary projection position data.

[0010] Further, each of the auxiliary metal members is disposed on the side wall of the main mold body at a preset angle, and the auxiliary metal members located on one side of the central cross-section are disposed on a cross-section parallel to the central cross-section.

[0011] Further, the main metal member and the auxiliary metal member are respectively solid metal spheres.

[0012] Further, the main mold body is made of hollow glass material, and the main metal member and the auxiliary metal member are respectively disposed on the glass side wall of the main mold body.

[0013] According to another aspect of the present invention, there is provided a method for detecting the accuracy of a device based on a medical phantom, which is applied to a medical phantom and includes:

[0014] After determining that the medical phantom is placed at a preset scanning position, voltage-level tomographic scanning is performed at a scanning interval angle, and target point position data matching a pair of main metal members on the medical phantom is collected. The target point position data is determined based on the first connection point between the first main projection position data scanned at the scanning interval angle by the pair of main metal members, the second connection point between the second main projection position data, the first main projection position data, and the second main projection position data;

[0015] Determine the detector flat twist angle according to the straight-line angle between the first connection point and the second connection point, and rotate and correct the position angle of the target point position data according to the detector flat twist angle so that the angle of the detector flat twist angle is set to zero;

[0016] Determine the device rotation parameters corresponding to the voltage-level tomographic scanning based on the projection position data corresponding to the target point position data after rotation correction, as the detection result of the device accuracy detection.

[0017] Further, the determining the device rotation parameters corresponding to the voltage-level tomographic scanning based on the projection position data corresponding to the target point position data after rotation correction includes:

[0018] Perform geometric shape fitting based on the first connection point, the second connection point, the first main projection position data, and the second main projection position data in the target point position data after correction to determine the fitting shape parameters, and calculate the device rotation parameters according to the fitting shape parameters. The device rotation parameters include the rotation axis distance, the detector distance, the direction deviation, the connection point slope and intercept.

[0019] Further, before performing the voltage-level tomographic scanning at the scanning interval angle and collecting the target point position data matching a pair of main metal members on the medical phantom, the method further includes:

[0020] Determine the relative position of the medical phantom for performing voltage-level tomography based on the auxiliary projection position data of at least one pair of auxiliary metal parts;

[0021] If the relative position matches the preset scanning position, perform voltage-level tomography on the medical phantom.

[0022] Further, the determining the relative position of the medical phantom for performing voltage-level tomography based on the auxiliary projection position data of at least one pair of auxiliary metal parts includes:

[0023] Obtain the auxiliary projection position data corresponding to at least one pair of auxiliary metal parts, and connect the auxiliary projection position data at symmetric positions to determine the central projection position;

[0024] Based on the comparison between the central projection position and the position of the equipment gantry, determine the relative position of the medical phantom for performing voltage-level tomography.

[0025] According to another aspect of the present invention, there is provided a device accuracy detection system based on a medical phantom, including: a medical phantom and a tomography system, where the medical phantom is configured to be placed in the tomography system for scanning to complete the device accuracy detection of the tomography system.

[0026] By means of the above technical solutions, the technical solutions provided by the embodiments of the present invention have at least the following advantages:

[0027] The present invention provides a medical phantom, as well as a device accuracy detection method and system based on the medical phantom. Compared with the prior art, the medical phantom in the embodiments of the present invention includes a main phantom and a metal part group provided on the side wall of the main phantom; wherein, the metal part group includes at least one pair of main metal parts, and a pair of the main metal parts are symmetrically arranged with respect to the central cross-section of the main phantom; after the main phantom is placed in the tomography system for scanning, the main projection position data of the main metal parts are obtained, and based on the main projection position data, the device accuracy detection of the tomography system is performed, realizing the high automation of device accuracy detection, achieving the purpose of repeatable execution of the detection of the tomography device, greatly saving human resources, and meeting the targeted detection requirements, thereby improving the accuracy of device accuracy detection.

[0028] The above description is only an overview of the technical solutions of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention are specifically described below. Description of the Drawings

[0029] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0030] Figure 1 A schematic structural diagram of a medical phantom provided by an embodiment of the present invention is shown;

[0031] Figure 2 A schematic diagram of image data obtained by scanning with a gantry angle of 0° provided by an embodiment of the present invention is shown;

[0032] Figure 3 A flowchart of a method for detecting device accuracy based on a medical phantom provided by an embodiment of the present invention is shown;

[0033] Figure 4 A schematic structural diagram of a medical phantom entity provided by an embodiment of the present invention is shown;

[0034] Figure 5 A schematic diagram of projection image data obtained by scanning a main metal part with the gantry rotation provided by an embodiment of the present invention is shown;

[0035] Figure 6 A schematic diagram of the main metal part projection position data C1 corresponding to the main metal part P2 provided by an embodiment of the present invention is shown;

[0036] Figure 7 A schematic diagram of the main metal part projection position data C2 corresponding to the main metal part P3 provided by an embodiment of the present invention is shown;

[0037] Figure 8 A flowchart of another method for detecting device accuracy based on a medical phantom provided by an embodiment of the present invention is shown;

[0038] Figure 9 A schematic diagram of the central projection point of a main phantom provided by an embodiment of the present invention is shown;

[0039] Figure 10 A block diagram of a device accuracy detection system based on a medical phantom provided by an embodiment of the present invention is shown. Detailed Embodiments

[0040] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art.

[0041] The detection of the geometric accuracy based on the accelerator is usually based on manually using auxiliary calibration tools such as coordinate paper, straight rulers, front pointers, and detection plates for manual accuracy detection, visually positioning the auxiliary calibration tools with a laser lamp, and measuring errors using measuring tools. However, manual accuracy detection inevitably introduces human errors, has poor repeatability and inaccurate detection accuracy, and there are many items that need to be detected for geometric accuracy in the accelerator. Multiple manual operations are time-consuming and laborious, and will bring additional radiation hazards to the operators. Embodiments of the present invention provide a medical phantom, such as Figure 1 shown, including: a main phantom 100, and a metal part group 200 provided on the side wall of the main phantom 100;

[0042] Wherein, the metal part group 200 includes at least a pair of main metal parts 201, and a pair of the main metal parts 201 are symmetrically arranged with respect to the central cross-section of the main phantom 100;

[0043] After the main phantom 100 is scanned in a tomographic scanning system, the main projection position data of the main metal part 201 is obtained, and the equipment accuracy of the tomographic scanning system is detected based on the main projection position data.

[0044] In the embodiments of the present invention, the metal part group 200 includes at least a pair of main metal parts 201. At this time, a pair of main metal parts 201 are symmetrically arranged with respect to the central cross-section of the main phantom 100. At this time, the distances of the two main metal parts 201 in a pair from the central cross-section can be preset, such as both being 110 mm away from the central cross-section, without specific limitation. At the same time, the main metal part 201 is provided on the side wall of the main phantom 100. If the main phantom 100 is solid, the side wall is the outer wall. If the main phantom 100 is a hollow cylinder, the main metal part 201 can be provided on the inner side or the outer side of the cylinder side wall of the main phantom 100, which is not specifically limited in the embodiments of the present invention. Preferably, the main phantom 100 is a hollow cylinder made of glass material, which can be a cylindrical barrel or an elliptical barrel, which is not specifically limited in the embodiments of the present invention.

[0045] It should be noted that the metal part group 200 on the main body 100 includes at least a pair of main metal parts 201. When the medical phantom in the embodiment of the present invention is placed in a tomographic scanning system for scanning, in order to perform equipment accuracy detection based on the projection position data obtained by scanning the metal part group 200, the metal part group 200 is a solid metal sphere, and the material of the metal sphere can be alloy steel, preferably tungsten steel, and the embodiment of the present invention does not make specific limitations. At the same time, in order to make only the projection position data of the metal part group 200 shown in the obtained scanning data and avoid introducing the outer shape of the main body 100, the main body 100 is made of glass, preferably hollow glass, so that the main metal part 201 is arranged on the glass side wall of the main body 100. At this time, the diameter of the cylindrical shape formed by the main body 100 is preferably 200 mm, so that the diameter of the ring of the projection position data of the main metal part 201 is also 200 mm.

[0046] The present invention provides a medical phantom. The medical phantom in the embodiment of the present invention includes a main body and a metal part group arranged on the side wall of the main body; wherein, the metal part group includes at least a pair of main metal parts, and a pair of the main metal parts are symmetrically arranged with respect to the central cross-section of the main body; after the main body is placed in a tomographic scanning system for scanning, the main projection position data of the main metal parts are obtained, so as to perform equipment accuracy detection of the tomographic scanning system based on the main projection position data, realize high automation of equipment accuracy detection, realize the purpose of repeatable execution of the detection of the tomographic scanning equipment, greatly save human resources, and meet the targeted detection requirements, thereby improving the accuracy of equipment accuracy detection.

[0047] Furthermore, as Figure 1 shown, the metal part group 200 further includes at least a pair of auxiliary metal parts 202, and each pair of the auxiliary metal parts 202 are symmetrically arranged with respect to the central cross-section of the main body 100;

[0048] wherein, after the main body 100 is placed in the tomographic scanning system for scanning, the auxiliary projection position data of the auxiliary metal parts 202 are obtained, so as to correct the relative position of the main body 100 in the tomographic scanning system based on the auxiliary projection position data.

[0049] In order to perform accuracy detection on a tomography system based on a medical phantom, before scanning the main phantom 100 provided with the main metal part 201, it is necessary to correct the relative position of the main phantom 100 in the tomography system. Specifically, the metal part group 200 further includes at least a pair of auxiliary metal parts 202, and each pair of auxiliary metal parts 202 is symmetrically arranged with respect to the central section of the main phantom 100, so that when the tomography system performs an initial scan on the main phantom 100, auxiliary projection position data with positions symmetric with respect to the central section is obtained. Among them, in order to better perform relative position correction, the auxiliary metal parts 202 are usually preferably 6 pairs, and relative position correction is performed based on the obtained 6 pairs of auxiliary projection position data.

[0050] Furthermore, in order to obtain auxiliary projection data of the auxiliary metal parts 202 that are symmetric with respect to the central section and whose projection positions are used for position correction, each of the auxiliary metal parts 202 is arranged on the side wall of the main phantom 100 at a preset angle, and the auxiliary metal parts 202 located on one side of the central section are arranged on a section parallel to the central section.

[0051] Among them, the preset angle can be an integer divisor of 360°, so as to evenly divide and arrange one of a pair of auxiliary metal parts 202 on a section on one side of the central section, that is, one of the auxiliary metal parts 202 in each pair of auxiliary metal parts 202 is arranged on a section parallel to the central section on one side of the central section. At the same time, one metal part of all pairs of auxiliary metal parts 202 is evenly arranged on a section at a preset angle, so that after platform scanning based on the tomography system, the projection positions corresponding to the main metal part 201 and the auxiliary metal parts 202 as shown in Figure 2 are obtained. For example, the auxiliary metal parts 202 are preferably solid small balls made of metal, arranged on the circumference of the side wall of the main phantom 100. The included angle formed by the connection lines of every two auxiliary metal parts 202 and the center of the circle is 30°. The diameters of the two formed circles are both 200 mm, and the distance from the central section is 50 mm. The embodiments of the present invention do not make specific limitations.

[0052] Preferably, each of the auxiliary metal parts 202 is respectively arranged on the side wall of the main phantom 100, and both the auxiliary metal parts 202 and the main metal part 201 are solid metal spheres. In order to show different projection effects, the diameters of the auxiliary metal parts 202 and the main metal part 201 as solid metal spheres can be different. For example, the diameter of the auxiliary metal parts 202 is preferably 3 mm, and the diameter of the main metal part 201 is preferably 5 mm. The embodiments of the present invention do not make specific limitations. In addition, a central metal part can also be arranged at the intersection of the central section and the side wall of the main phantom 100, so as to use the central projection position data of the central metal part as the basis for correcting the main projection position data, the auxiliary projection position data, and the relative position.

[0053] The present invention provides a medical phantom. The medical phantom in the embodiments of the present invention includes a main phantom and a metal part group arranged on the side wall of the main phantom. Wherein, the metal part group includes at least a pair of main metal parts, and a pair of the main metal parts are symmetrically arranged with respect to the central cross-section of the main phantom; the metal part group further includes at least a pair of auxiliary metal parts, and each pair of the auxiliary metal parts are symmetrically arranged with respect to the central cross-section of the main phantom, so as to perform relative position correction of the tomographic scanning system based on the auxiliary projection position data, improve the accuracy of equipment precision detection based on the main phantom, realize the high automation of equipment precision detection, achieve the purpose of repeatable execution of the detection of tomographic scanning equipment, greatly save human resources, and meet the targeted detection requirements, thereby improving the accuracy of equipment precision detection.

[0054] Embodiments of the present invention provide a method for detecting equipment precision based on a medical phantom, which is applied to a medical phantom, as Figure 3 shown, and includes:

[0055] 301. After determining that the medical phantom is placed at a preset scanning position, perform voltage-level tomographic scanning at a scanning interval angle, and collect target point position data matching a pair of main metal parts on the medical phantom.

[0056] In the embodiments of the present invention, as Figure 4 shown, the medical phantom is a hollow glass cylindrical barrel, and main metal parts are arranged on the side wall, such as the tungsten steel solid spheres represented at P2 and P3. During the tomographic scanning at different voltage levels, the medical phantom is located on the treatment bed of the rotating gantry, so as to perform, at different scanning interval angles in the rotating gantry, as Figure 5During the scanning as shown, scan image data corresponding to tomographies at different voltage levels are obtained. Specifically, voltage-level tomography is tomography performed at different voltage levels, such as cone-beam CT scanning at the KV voltage level, simply referred to as KV-CBCT (KV-Cone Beam Computed Tomography), and cone-beam CT scanning at the MV voltage level, simply referred to as MV-CBCT (MV-Cone Beam Computed Tomography). The embodiments of the present invention are not specifically limited. Among them, in order to detect the equipment accuracy based on tomographies at different voltage levels, the target point position data is determined based on the first connection point between the first main projection position data obtained by scanning at a scanning interval angle according to a pair of main metal parts, the second connection point between the second main projection position data, the first main projection position data, and the second main projection position data. When performing tomographies at different voltage levels, first, the medical phantom needs to be placed on the treatment bed of the tomography system to be executed. This treatment bed is located in the gantry, and one end of the bracket of the medical phantom is horizontally placed on the treatment bed, and the other end is clamped at both ends of the treatment bed by the clamping device of the bracket to ensure that there is no relative movement between the medical phantom and the treatment bed. At this time, the outer wall scale line of the medical phantom is aligned with the laser lamp, so that the position where the medical phantom is placed is close to the isocenter position corresponding to the rotation axis of the gantry, that is, the preset scanning position is the position on the scanning bed close to the isocenter, so as to perform voltage-level tomography according to the scanning interval angle.

[0057] During the voltage-level tomography process, the rotation angle of the rotating gantry can be configured as the scanning interval angle, such as an interval of 30 degrees, so as to obtain a total of 12 projection images of the rotation gantry angles. The projection position points of a pair of main metal parts are determined on each projection image. Since main metal parts are provided on the side wall of the main body of the medical phantom, and the main metal parts are made of metal material, such as solid tungsten steel balls, to combine with the phantom made of organic grinding material, reduce the attenuation of the ray by the outer wall of the phantom, and ensure the clarity of the main metal parts in the projection image, such as Figure 4 the small balls at the P2 and P3 positions shown in the figure. The embodiments of the present invention are not specifically limited. At this time, the main projection position data of the main metal parts at P2 and P3 are included in the scanned projection image, that is, used as the first main projection position data and the second main projection position data. Among them, since the main metal parts P2 and P3 are respectively located on both sides of the central section of the main body of the phantom, symmetrically away from the central section and at a predetermined distance, such as 110 mm, to obtain the first main projection position data and the second main projection position data obtained by scanning P2 and P3. From such as Figure 6The first principal projection position data corresponding to P2 in the figure can be determined. Under the same voltage level, the projection position of the same main metal part changes into an ellipse. Therefore, connect the projection position of a main metal part with the symmetric projection position when rotated 180°, and obtain an intersection point C1 of the connection line, which is the center of the ellipse, as shown in Figure 7 The intersection point C2 of the connection line corresponding to P3 is shown in the figure. Specifically, when performing tomographic scanning at the MV voltage level, the first principal projection position data is the projection position data of the main metal part P2 under 12 MV voltage tomographic scans. Connect the position points symmetric when rotated 180° to obtain the first intersection point of the connection line. Correspondingly, the second principal projection position data is the projection position data of the main metal part P3 under 12 MV voltage tomographic scans. Connect the position points symmetric when rotated 180° to obtain the second intersection point of the connection line. At this time, determine the first intersection point of the connection line, the second intersection point of the connection line, and the corresponding first principal projection position data and second principal projection position data at the MV voltage level as the target point position data to obtain the target point position data.

[0058] It should be noted that when performing voltage-level tomographic scanning, X-ray scanning is based on a linear accelerator, and the rotating gantry needs to perform X-ray scanning at different gantry angles according to the rotation axis, so as to obtain the tomographic scanning projection position data of the main metal part at different gantry angles. At this time, due to the gantry rotation scanning, a circle or an ellipse will be formed for the obtained scanning projection position data. Therefore, the target point position data is the position data of the center of the circle or ellipse corresponding to the tomographic scanning projection position data corresponding to the main metal part.

[0059] 302. Determine the detector flat torsion angle according to the straight-line angle between the first intersection point of the connection line and the second intersection point of the connection line, and rotate and correct the position angle of the target point position data according to the detector flat torsion angle so that the angle of the detector flat torsion angle is set to zero.

[0060] In the embodiments of the present invention, during tomographic scans at different voltage levels, the acquisition of scanned image data is based on the detector flat panel. Since the detector flat panel is manually installed in a position parallel to the rotation axis of the gantry and there is a certain torsional angle, it is necessary to correct the target point data obtained from the tomographic scans at different voltage levels. The torsional angle of the detector flat panel is calculated based on the target point data obtained from the tomographic scans at different voltage levels for correction. Specifically, since the target point data includes the projection position data corresponding to at least two reference objects, a line can be connected based on these two projection position data, and the slope of the line is used as the torsional angle of the detector flat panel, that is, the torsional angle of the detector flat panel is determined according to the straight line angle between the first line connection intersection and the second line connection intersection, and the position angle of the target point data is rotationally corrected according to the torsional angle of the detector flat panel.

[0061] Specifically, during the tomographic scans at different voltage levels, the projection position data of a pair of main metal parts can be identified in each projection image data. Therefore, based on the multiple projection image data obtained from the scans, all the position data of the main metal parts P2 and P3 in the multiple projection image data are summarized into a coordinate system, thereby forming an ellipse corresponding to each of P2 and P3. Connect the two projection positions with a 180° gantry angle interval in each ellipse. More than 6 intersecting lines are obtained for each ellipse, that is, the first line connection intersection point C1(u1, v1) is obtained. The second line connection intersection point C2(u2, v2) is the center of the ring in the target phantom. At this time, to determine whether there is torsion of the detector flat panel, a line is connected based on the two line connection intersection points, and the straight line angle of this line, that is, the slope, is used as the torsional angle of the detector flat panel.

[0062] For example, through the first line connection intersection point C1(u1, v1) and the second line connection intersection point C2(u2, v2), as Figure 6 、 7 shown, the straight line equation of the line connecting the two intersection points is constructed: Among them, k axis is the straight line angle, that is, the slope, b axis is the intercept. At this time, the torsional angle η of the detector flat panel is determined through the straight line angle, that is, the slope;

[0063] In addition, for tomographic scans at different voltage levels, such as the tomographic scans at the MV voltage level and the tomographic scans at the KV voltage level, after determining the connection angles respectively, the method for calculating the torsional angle of the detector flat panel is the same. The only difference is the number of multiple projection image data collected by the scans. Therefore, the torsional angle of the detector flat panel can be determined according to the straight line angle between the first line connection intersection and the second line connection intersection, and the embodiments of the present invention do not make specific limitations.

[0064] In an embodiment of the present invention, after determining the torsional angle of the detector flat panel, in order to ensure that the detector flat panel is parallel to the frame rotating shaft when detecting the equipment accuracy, therefore, the target point position data is corrected by the obtained torsional angle of the detector flat panel. Specifically, the position angle of the target point position data obtained by scanning is rotationally corrected according to the torsional angle of the detector flat panel obtained under voltage-level tomography, that is, the position angles of the projection position data of the first target reference object and the projection position data of the second target reference object are rotated respectively according to the first torsional angle of the detector flat panel, that is, the angle of the torsional angle of the detector flat panel is set to 0, so that the target point position data at this time is regarded as the data obtained by scanning without the detector flat panel being twisted, and the corrected projection position data of the main metal part is the projection position data obtained without the detector flat panel being deflected.

[0065] It should be noted that when rotationally correcting the position angle of the target point position data based on the torsional angle of the detector flat panel, since the target point position data is obtained by summarizing the position projections of the main metal part in multiple projection image data into one coordinate system, therefore, the position angle of the target point position data is in the same coordinate system as the torsional angle of the detector flat panel, so that it can be rotated in the y-axis direction, and the position angle of the target point position data is rotationally corrected according to the torsional angle of the detector flat panel, so that the angle of the torsional angle of the detector flat panel is set to zero.

[0066] 303. Determine the equipment rotation parameters corresponding to the voltage-level tomography based on the projection position data corresponding to the target point position data after rotation correction, as the detection result of the equipment accuracy detection.

[0067] Among them, the equipment rotation parameters are used to characterize the objects to be detected during the rotation scanning of the equipment, including but not limited to the rotation axis distance, the detector distance, the direction deviation, the slope and intercept of the intersection of the connection lines. Therefore, based on the equipment rotation parameters, the detection result of the equipment accuracy can be determined. Specifically, the equipment rotation parameters can be calculated based on the projection position data corresponding to the target point position data, so that the equipment rotation parameters include the rotation axis distance, the detector distance, the direction deviation, the slope and intercept of the intersection of the connection lines. Among them, the rotation axis distance is the distance from the equipment target point to the frame rotating shaft (source axis distance, sad), the detector distance is the distance from the equipment target point to the detector (source imager distance, sid), the direction deviation is the deviation of the position of the flat panel detector relative to the spatial direction of the frame, and the slope and intercept of the intersection of the connection lines are the slope and intercept of the connection line of the centers of the two circles or ellipses formed by the projection position data corresponding to the target point position data. The embodiments of the present invention do not make specific limitations.

[0068] It should be noted that the target point data is obtained based on the tomographic scanning projection position data corresponding to the main metal part on the medical phantom. Therefore, the projection position data corresponding to the target point data is the projection position data of the main metal part, so that the device rotation parameters are calculated based on the projection position data of the main metal part.

[0069] In another embodiment of the present invention, for further definition and explanation, the step of determining the device rotation parameter corresponding to the voltage level tomography based on the projection position data corresponding to the target point data after rotation correction includes:

[0070] Based on the first line intersection point, the second line intersection point, the first main projection position data, and the second main projection position data in the target point data after correction, geometric shape fitting is performed to determine the fitting shape parameters, and the device rotation parameters are calculated according to the fitting shape parameters. The device rotation parameters include the rotation axis distance, the detector distance, the direction deviation, the slope and the intercept of the line intersection point.

[0071] In order to accurately calculate the rotation parameters of the device as the result of the device geometric accuracy detection, when determining the rotation parameters of the device based on the line intersection in the target point data, since the target point data is the center of the circle corresponding to the geometric shape formed based on the main projection position data, as the projection position point forming this geometric figure, the first main projection position data P2, the second main projection position data P3, the first line intersection C1, and the second line intersection C2 are used to perform geometric shape fitting to determine the fitting shape parameters. Among them, the detector plate is rotated tomographically scanned according to the rack rotation axis, so the image obtained by geometric shape fitting is an ellipse or a circle, so as to determine the shape parameters of the ellipse or the circle, such as the coordinates of the center of the ellipse, the parameters in the mathematical expression formula of the ellipse, etc., which are not specifically limited in the embodiment of the present invention.

[0072] For example, using the least squares method, the projection coordinates of the solid balls used as the two main metal parts rotated one circle are fitted, and two ellipse equations and parameters are obtained by fitting. Using the least squares method, the projection coordinates of the two balls rotated one circle are fitted, and two ellipse equations and parameters are obtained by fitting: p0u 2 +v 2 -2p1u-2p2v+2p3uv+p4=0, where u and v represent projection coordinate parameters, respectively, to indicate that the projection position data is in the u and v coordinate systems, p0, p1, p2, p3, and p4 are the parameters of the ellipse direction, and the coordinates of the center of the ellipse are expressed as Expressed as

[0073] It should be noted that since the expected calculated device rotation parameters include the rotation axis distance, the detector distance, the direction deviation, the slope and intercept of the intersection point of the connection lines, after determining the fitting shape parameters, based on these fitting shape parameters to calculate the device rotation parameters, first, the above-mentioned fitting shape parameters can be standardized to quickly calculate the rotation axis distance, the detector distance, the direction deviation, the slope and intercept of the intersection point of the connection lines.

[0074] For example, the fitting shape parameters include: b = a / p0, c = p3b, to use a, b, c as intermediate parameters to calculate the rotation axis distance, the detector distance, the direction deviation, the slope and intercept of the intersection point of the connection lines. Furthermore, intermediate variables can also be constructed based on the above-mentioned fitting shape parameters a, b, c. Among them, a i , b i , c i are respectively for the i-th voltage level tomography, i = 1, 2, k = 1, 2. When two metal solid balls P2 and P3 are respectively distributed on both sides of the central section of the main phantom, z1 > 0, z2 < 0.

[0075] Specifically, the rotation axis distance is the distance from the device target point to the rotation axis (source axis distance, sad), the detector distance is the distance from the device target point to the detector (source imager distance, sid), the direction deviation is the deviation of the detector flat position in the u and v directions, and the slope and intercept of the intersection point of the connection lines are the slope and intercept of the straight line formed by the first intersection point C1 and the second intersection point C2.

[0076] For example, the calculation method of the detector distance sid is: Among them, a is a in the above intermediate parameters, a1 is the fitting shape parameter of the elliptical shape corresponding to the projection position data P2 of the first main metal part, n is, n0 is, n1 is. The calculation method of the rotation axis distance sad is: Among them, d is the actual distance between the solid balls of the target reference object. are respectively the u and v coordinate data of the projections of the solid balls of the two main metal parts, N is the number of exposures per rotation, N = 1, 2... The calculation method of the direction deviation (u0, v0) is: The calculation method of the slope and intercept of the intersection point of the connection lines is: b = v1 - k * u1.

[0077] In order to further detect the equipment accuracy, when performing computed tomography based on a linear accelerator, a tomographic scanning system with different voltage levels can be configured in the gantry equipment, so as to perform tomographic scans with different voltage levels on the same main phantom to determine the detection of the equipment geometric accuracy. Among them, the voltage-level tomographic scan includes a first-voltage-level tomographic scan, such as an MV-voltage-level tomographic scan, and a second-voltage-level tomographic scan, such as a KV-voltage-level tomographic scan. The embodiments of the present invention do not make specific limitations. For the first-voltage-level tomographic scan and the second-voltage-level tomographic scan, the method for calculating the equipment rotation parameters is the same. The only difference is that the MV-voltage-level tomographic scan is performed at 30° intervals to obtain 12 pieces of projection image data, and the KV-voltage-level tomographic scan is performed at 3° intervals to obtain 120 pieces of projection image data. At this time, a pair of position points corresponding to the main metal parts P2 and P3 can be determined on each projection image, which will not be elaborated in the embodiments of the present invention. Therefore, based on the execution of steps 101-103, the first direction deviation corresponding to the first-voltage-level tomographic scan and the second direction deviation corresponding to the second-voltage-level tomographic scan can be obtained based on the projection position data in the projection image data, so as to construct the equipment geometric relationship.

[0078] In the embodiments of the present invention, since the equipment for collecting scanned images is fixed on a gantry system for tomographic scans with different voltage levels, therefore, when the main phantom remains unchanged, the positions of the gantry rotation axes for performing the first-voltage-level tomographic scan and the second-voltage-level tomographic scan respectively are fixed and unchanged. Obtaining different equipment rotation parameters can detect the equipment combination accuracy for a set of gantry equipment. Therefore, after determining the tomographic scans with different voltage levels, the equipment geometric relationship between the first-voltage-level tomographic scan and the second-voltage-level tomographic scan is constructed. Among them, the equipment geometric relationship is used to characterize the equipment isocenter geometric relationship between the acquisition system for performing the first-voltage-level tomographic scan and the acquisition system for performing the second-voltage-level tomographic scan in the tomographic scanning equipment, such as the equipment isocenter coincidence relationship, the equipment isocenter intersection relationship, etc. The embodiments of the present invention do not make specific limitations. At this time, calculations can be performed based on the slope and intercept of the first connection point and the slope and intercept of the second connection point obtained from the first-voltage-level tomographic scan.

[0079] Specifically, according to the equipment geometric relationship, the slope and intercept of the first connection point corresponding to the first-voltage-level tomographic scan, and the slope and intercept of the second connection point corresponding to the second-voltage-level tomographic scan, calculate the equipment isocenter coincidence error. Specifically, first determine the slope and intercept of the first connection point corresponding to the first-voltage-level tomographic scan, and the slope and intercept of the second connection point obtained from the second-voltage-level tomographic scan. For example, determine the slope of the connection point of the KV-voltage-level tomographic scan Intercept b KV = v1 - k KV*u1, the slope of the intersection point of the connection lines of the MV voltage-level tomography Intercept b MV = v1' - k MV *u1', where (u1, v1) and (u2, v2) are the projection position data corresponding to the main metal parts P2 and P3 obtained by the KV voltage-level tomography, and (u1', v1') and (u2', v2') are the projection position data corresponding to the target reference objects P2 and P3 obtained by the MV voltage-level tomography. At this time, by combining with the rotation axis equation, the isocenter coincidence error formula is obtained as:

[0080] Among them,

[0081] It should be noted that the acquisition system for performing the first voltage-level tomography and the acquisition system for performing the second voltage-level tomography are respectively installed in the rotation gantry space in the embodiments of the present invention, so as to perform tomography with the same gantry rotation axis and the target phantom to determine the detection results of the equipment geometric accuracy between the two acquisition systems. Moreover, the first voltage-level tomography and the second voltage-level tomography can be executed in a predetermined order, and the acquired scan image data is stored in the current execution entity, so as to be obtained when performing the equipment geometric accuracy detection to execute the methods in steps 101-103.

[0082] In another embodiment of the present invention, for further limitation and illustration, as Figure 8 described, before the step of performing voltage-level tomography according to the scanning interval angle and acquiring the target point position data matching a pair of main metal parts on the medical phantom, the method further includes:

[0083] 401. Determine the relative position of the medical phantom for performing the voltage-level tomography based on the auxiliary projection position data of at least a pair of auxiliary metal parts;

[0084] 402. If the relative position matches the preset scanning position, perform the voltage-level tomography on the medical phantom.

[0085] To ensure the accurate position and stability of the medical phantom including the main phantom and the metal part group provided on the side wall of the main phantom on the gantry machine tool, the metal part group further includes at least a pair of auxiliary metal parts, such as Figure 4P4 and P5 shown in the figure. Preferably, there are 6 auxiliary metal parts arranged in a plane corresponding to P4 and P5 respectively. The 6 auxiliary metal parts in each plane form a ring, which are respectively distributed on both sides of the central section of the main body, and are symmetric with the central section of the main body. At this time, the auxiliary metal parts are preferably solid metal balls, which are arranged on the circumferential wall of the main body. The included angle formed by the connection line of every two auxiliary metal parts and the center of the ring is 30°. The diameters of the two formed rings are both 200 mm, and the distance from the central section is 50 mm. Among them, the diameters of P4 and P5 are 5 mm, and the diameters of other auxiliary metal parts can be 3 mm, so as to obtain as Figure 2 shown in the tomographic scan projection image data when the frame angle is 0°. In addition, as Figure 4 shown, P1 is the central metal part set at the intersection of the central section and the side wall of the main body. Based on the central projection position data of the central metal part as the basis for correcting the main projection position data, the auxiliary projection position data, and the relative position, the projection position points of the central metal part as Figure 2 shown are obtained.

[0086] When the frame angle is 0°, the main body is placed in the frame machine tool, so that the current execution end determines the relative position of the main body to perform voltage-level tomographic scanning based on the auxiliary projection position data of at least two pairs of auxiliary metal parts, that is, the projection image data corresponding to the tomographic scanning performed at frame 0° can determine the auxiliary projection position data, that is, the scanning projection positions of the solid metal balls in the projection diagram as Figure 2 shown, to determine the relative position of the main body to perform voltage-level tomographic scanning. If the relative position matches the preset scanning position, then perform voltage-level tomographic scanning on the main body. At this time, the preset scanning position is the pre-specified position where the main body is at the isocenter of the device, so that the device can stably and accurately perform voltage-level tomographic scanning on the medical phantom.

[0087] In another embodiment of the present invention, for further limitation and explanation, the step of determining the relative position of the medical phantom to perform the voltage-level tomographic scanning based on the auxiliary projection position data of at least one pair of auxiliary metal parts includes:

[0088] Obtain the auxiliary projection position data corresponding to at least one pair of auxiliary metal parts, and connect the auxiliary projection position data at symmetric positions to determine the central projection position;

[0089] Based on the comparison between the central projection position and the device frame position, determine the relative position of the medical phantom to perform the voltage-level tomographic scanning.

[0090] In the embodiment of the present invention, in order to ensure that the relative position of the main body in the frame machine tool is accurate, the auxiliary projection position data determines the relative position of the main body for performing voltage-level tomography. Specifically, an initial tomography scan is performed at a frame angle of 0°, and the auxiliary projection position data of all auxiliary metal parts of P4, P5 and the formed ring corresponding to P4 and P5 are obtained, so as to connect the auxiliary projection position data corresponding to each pair of auxiliary metal parts. At this time, the auxiliary metal part P4 and the symmetric auxiliary metal part corresponding to 180° form a pair, as Figure 9 shown, the intersection point of the connection line between each pair of auxiliary projection position data is the central projection position.

[0091] It should be noted that in order to ensure the accurate placement position of the medical phantom, based on the comparison between the central projection position and the device frame position, the relative position of the medical phantom for performing voltage-level tomography is determined, that is, based on the comparison between the central projection position and the pre-determined device frame position in a coordinate system. If there is a deviation, the relative position of the medical phantom can be determined for re-adjustment. Or, a position coordinate system is established based on this relative position. The embodiment of the present invention does not make specific limitations.

[0092] The present invention provides a method for detecting the accuracy of a device based on a medical phantom. Compared with the prior art, in the embodiment of the present invention, after determining that the medical phantom is placed at a preset scanning position, voltage-level tomography is performed at a scanning interval angle, and the target point data matching a pair of main metal parts on the medical phantom is collected; the torsion angle of the detector flat plate is determined according to the straight line angle between the first connection point and the second connection point, and the position angle of the target point data is rotationally corrected according to the torsion angle of the detector flat plate, so that the angle of the torsion angle of the detector flat plate is set to zero; based on the projection position data corresponding to the target point data after rotational correction, the device rotation parameters corresponding to the voltage-level tomography are determined as the detection result of the device accuracy detection, realizing the high automation of the device accuracy detection, realizing the repeatable executability purpose of the detection of the tomography device, greatly saving human resources, and meeting the targeted detection requirements, thereby improving the accuracy of the device accuracy detection.

[0093] The embodiment of the present invention provides a device accuracy detection system based on a medical phantom, as Figure 10 shown, including: a medical phantom 51 and a tomography system 52. The medical phantom 51 is used to be placed in the tomography system 52 for scanning to complete the device accuracy detection of the tomography system 52;

[0094] Specifically, the medical phantom includes a main body and a metal part group arranged on the side wall of the main body;

[0095] Among them, the metal part group includes at least a pair of main metal parts, and a pair of the main metal parts are symmetrically arranged with respect to the central cross-section of the main mold body;

[0096] After the main mold body is placed in the tomographic scanning system 52 for scanning, the main projection position data of the main metal parts are obtained, so as to perform equipment accuracy detection of the tomographic scanning system 52 based on the main projection position data;

[0097] The tomographic scanning system 52 is configured to, when it is determined that the medical phantom 51 is placed at a preset scanning position, perform voltage-level tomographic scanning at a scanning interval angle, and collect target point position data matching a pair of main metal parts on the medical phantom 51. The target point position data is determined based on the first connection point between the first main projection position data obtained by scanning the pair of main metal parts at the scanning interval angle, the second connection point between the second main projection position data, the first main projection position data, and the second main projection position data; determine the detector flat torsion angle according to the straight-line angle between the first connection point and the second connection point, and rotate and correct the position angle of the target point position data according to the detector flat torsion angle, so that the angle of the detector flat torsion angle is set to zero; determine the equipment rotation parameter corresponding to the voltage-level tomographic scanning based on the projection position data corresponding to the target point position data after rotation correction, as the detection result of the equipment accuracy detection.

[0098] The present invention provides an equipment accuracy detection system based on a medical phantom. Compared with the prior art, after the main mold body of the medical phantom in the embodiment of the present invention is placed in a tomographic scanning system for scanning, the main projection position data of the main metal parts are obtained, so as to perform equipment accuracy detection of the tomographic scanning system based on the main projection position data, realizing high automation of equipment accuracy detection, achieving the purpose of repeatable execution of the detection of the tomographic scanning equipment, greatly saving human resources, and meeting targeted detection requirements, thereby improving the accuracy of equipment accuracy detection.

[0099] Obviously, those skilled in the art should understand that the above-mentioned modules or steps of the present invention can be implemented by a general-purpose computing device. They can be concentrated on a single computing device or distributed on a network composed of multiple computing devices. Optionally, they can be implemented by program codes executable by the computing device, so that they can be stored in a storage device and executed by the computing device. And in some cases, the steps shown or described can be executed in a different order than here, or they can be separately made into individual integrated circuit modules, or multiple modules or steps among them can be made into a single integrated circuit module to implement. In this way, the present invention is not limited to any specific combination of hardware and software.

[0100] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A medical phantom, characterized in that, Comprising: A main body, and a set of metal parts arranged on the side wall of the main body; Wherein, the set of metal parts includes at least a pair of main metal parts, and a pair of the main metal parts are symmetrically arranged with respect to the central cross-section of the main body; After the main body is placed in a tomographic scanning system for scanning, the main projection position data of the main metal parts are obtained, so as to perform equipment accuracy detection of the tomographic scanning system based on the main projection position data; The set of metal parts further includes at least a pair of auxiliary metal parts, and each pair of the auxiliary metal parts are symmetrically arranged with respect to the central cross-section of the main body; Wherein, after the main body is placed in the tomographic scanning system for scanning, the auxiliary projection position data of the auxiliary metal parts are obtained, so as to correct the relative position of the main body in the tomographic scanning system based on the auxiliary projection position data.

2. The medical phantom according to claim 1, wherein Each of the auxiliary metal parts is arranged on the side wall of the main body at a preset angle, and the auxiliary metal parts located on one side of the central cross-section are arranged on a cross-section parallel to the central cross-section.

3. The medical phantom according to claim 1, wherein The main metal parts and the auxiliary metal parts are respectively solid metal spheres.

4. The medical phantom according to claim 1, wherein The main body is made of hollow glass material, and the main metal parts and the auxiliary metal parts are respectively arranged on the glass side wall of the main body.

5. A method for detecting the accuracy of a device based on a medical phantom, characterized in that, Applied to the medical phantom according to any one of claims 1 to 4, the method includes: When it is determined that the medical phantom is placed at a preset scanning position, voltage-level tomographic scanning is performed at a scanning interval angle, and target point position data matching a pair of main metal parts on the medical phantom are collected. The target point position data are determined based on the first connection point between the first main projection position data obtained by scanning the pair of main metal parts at the scanning interval angle, the second connection point between the second main projection position data, the first main projection position data, and the second main projection position data; Determine the detector flat torsion angle according to the straight-line angle between the first connection point and the second connection point, and rotate and correct the position angle of the target point position data according to the detector flat torsion angle, so that the angle of the detector flat torsion angle is set to zero; Determine the equipment rotation parameters corresponding to the voltage-level tomographic scanning based on the projection position data corresponding to the target point position data after rotation correction, as the detection result of the equipment accuracy detection.

6. The method according to claim 5, wherein The determining the equipment rotation parameters corresponding to the voltage-level tomographic scanning based on the projection position data corresponding to the target point position data after rotation correction includes: Perform geometric shape fitting based on the first connection point, the second connection point, the first main projection position data, and the second main projection position data in the corrected target point position data to determine the fitting shape parameters, and calculate the equipment rotation parameters according to the fitting shape parameters. The equipment rotation parameters include the rotation axis distance, the detector distance, the direction deviation, the connection point slope and the intercept.

7. The method according to claim 5, wherein Before performing the voltage-level tomographic scanning at the scanning interval angle and collecting the target point position data matching a pair of main metal parts on the medical phantom, the method further includes: Determine the relative position of the medical phantom for performing the voltage-level tomography based on the auxiliary projection position data of at least one pair of auxiliary metal parts; If the relative position matches the preset scanning position, perform the voltage-level tomography on the medical phantom.

8. The method according to claim 7, wherein The determining the relative position of the medical phantom for performing the voltage-level tomography based on the auxiliary projection position data of at least one pair of auxiliary metal parts includes: Obtain the auxiliary projection position data corresponding to at least one pair of auxiliary metal parts, and connect the auxiliary projection position data at symmetric positions to determine the central projection position; Based on the comparison between the central projection position and the device gantry position, determine the relative position of the medical phantom for performing the voltage-level tomography.

9. A device accuracy detection system based on a medical phantom, characterized in that, Includes: The medical phantom according to any one of claims 1 to 4, and a tomography system, the tomography system being used to execute the device accuracy detection method based on the medical phantom according to any one of claims 6 to 8, the medical phantom being used to be placed in the tomography system for scanning to complete the device accuracy detection of the tomography system.

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