Model body device for accelerator performance index detection

Abstract

The utility model discloses a die body device for accelerator performance index detection, which comprises a cubic die body arranged on a base, the cubic die body is provided with a C-shaped surface piece and a main body structure, the C-shaped surface piece is C-shaped, and the main body structure is three-dimensional and is nested in the C-shaped surface piece. A functional mark is arranged on the outer surface of the C-shaped surface part, an arc groove is formed in the outer surface of the main body structure, and a set distance is arranged between the functional mark and the arc groove; the main body structure is provided with a first die body and a second die body which are nested with each other, and the second die body is hollow under the condition that the second die body is nested in the first die body. According to the invention, the detection function of performance indexes of a whole set of machine is integrated, the problems of numerous old tools and complex process are solved, a more universal QA motif with more comprehensive functions is provided for more hospital radiation departments, and important theoretical environment requirements are provided for production testing and scientific research experiments.

Description

Technical Field

[0001] The utility model relates to the technical field of phantom devices, in particular to a phantom device for detecting accelerator performance indicators. Background Art

[0002] Performance testing of medical linear accelerators is designed to ensure that machine performance does not deviate significantly from baseline values ​​obtained during acceptance and commissioning, and that these baseline values ​​are of the highest quality to prevent systematic errors from being transferred to the QA and treatment processes. Some baseline values ​​are used as input to the treatment planning system to describe and / or model the treatment machine. Therefore, these baseline values ​​may directly affect the calculation of treatment plans for every patient treated on this machine. Deviations from these baseline values ​​may result in suboptimal patient treatment.

[0003] Currently, performance testing of medical linear accelerators is conducted on a regular QA schedule, with daily, monthly, and annual inspections. These are primarily performed using a morning inspection instrument in conjunction with various tools. For example, the morning inspection instrument is used to test the accelerator's beam output, the KV / MV imaging module is used to capture KV / MV images, and various scales are used to measure and calibrate parameters such as the consistency between the accelerator's light field and the combined dose film. This multifaceted and time-consuming process necessitates optimization to achieve faster and more accurate results.

[0004] Optimizing and increasing the efficiency of medical accelerator performance testing processes is a market trend. Examples include the globally recognized Penta-Guide phantom from Modus Medical Devices and the MPC phantom for Varian accelerators. These phantoms utilize various surface or internal markings to enable testing of various accelerator performance indicators. For example, the cube-shaped Penta-Guide surface features functional markings such as a crosshair pointing to the center, lines indicating light field size, grooves marking light field accuracy, an internal cavity for imaging center indication, and a surface ring. Another example is the MPC phantom for Varian accelerators, whose base is specifically compatible with Varian accelerator treatment beds. Surface markings similarly enable accelerator performance testing. These phantoms, used in conjunction with supporting software, can rapidly test a wide range of accelerator performance indicators. Currently, the Penta-Guide and MPC phantoms are the primary accelerator performance testing phantoms available on the market. The MPC phantom is a Varian-developed performance testing phantom for its own accelerators and is therefore not suitable for other commercially available accelerators. The Penta-Guide phantom has a wide range of applications and is highly practical, but its cubic structure limits its scalability and lacks a base to secure it to the treatment bed, requiring adjustment of its position and level between uses. Therefore, this application aims to provide a phantom device for accelerator performance testing that overcomes these limitations. Utility Model Content

[0005] The purpose of the utility model is to overcome the shortcomings of the prior art and provide a phantom device for detecting accelerator performance indicators.

[0006] The purpose of the utility model is achieved through the following technical solutions: A phantom device for accelerator performance index detection includes a cubic phantom arranged on a base, the cubic phantom is configured with a C-shaped surface part and a main body structure, wherein: the C-shaped surface part is C-shaped, the main body structure is three-dimensional and nested in the C-shaped surface part, a functional mark is provided on the outer surface of the C-shaped surface part, and an arc groove is provided on the outer surface of the main body structure, wherein the functional mark is spaced a set distance from the arc groove; the main body structure has a first phantom and a second phantom nested in each other, and when the second phantom is nested in the first phantom, the second phantom is hollow.

[0007] Preferably, the functional mark includes a cross mark, a field size mark and a field accuracy mark, the shape of the field size mark can be defined by a quadrilateral, and the shapes of the cross mark and the field accuracy mark can both be defined by a cross, wherein the center of the cross mark does not coincide with the center of the field size mark, and the center of the field accuracy mark coincides with the center of the field size mark.

[0008] Preferably, the circular arc groove includes a first circular arc groove, a second circular arc groove and a third circular arc groove, the first circular arc groove is provided on the first side and the second side of the first mold body, the second circular arc groove is provided on the third side of the first mold body, and the third circular arc groove is provided on the fourth side of the first mold body, wherein the first side and the second side are perpendicular to each other, the second side and the third side are parallel to each other, the third side and the fourth side are perpendicular to each other, and the first side and the fourth side are parallel to each other.

[0009] Preferably, a cylindrical cavity is provided at each of the eight vertex positions of the first mold body.

[0010] Preferably, the thickness of the C-shaped surface part is 5 mm, and the set distance between the C-shaped surface part and the first mold body is 5 mm.

[0011] Preferably, the field size mark consists of three light field size frame lines with sizes of 5 cm*5 cm, 10 cm*10 cm, and 15 cm*15 cm, and the center of the cross mark deviates from the center of the field size mark by 1 cm.

[0012] Preferably, the first arc groove, the second arc groove and the third arc groove are each composed of a plurality of different arc groove segments having the same center.

[0013] Preferably, the base includes a first leg, a second leg, a body and a horizontal adjustment knob, the body is provided with a groove, the first leg and the second leg are both hinged to the body, and the horizontal adjustment knob is provided on the body, wherein the first leg and the second leg can be nested in the groove.

[0014] The utility model has the following advantages: it integrates the detection function of a whole set of machine performance indicators, solves the problem of numerous old tools and complicated processes, provides more universal and comprehensive QA phantoms for more hospital radiology departments, and provides important theoretical environment requirements for production testing and scientific research experiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic structural diagram of the phantom device of the present invention;

[0016] Figure 2 Schematic diagram of the structure of the C-type surface part

[0017] Figure 3 This is a schematic diagram of the structure of the mold device after removing the C-shaped surface part;

[0018] Figure 4 is a schematic structural diagram of the second model;

[0019] Figure 5 is a structural schematic diagram of the phantom device after removing the second phantom;

[0020] Figure 6 Schematic diagram of the structure of a cylindrical cavity;

[0021] Figure 7 Schematic diagram of the arrangement of the first arc groove, the second arc groove and the third arc groove;

[0022] In the figure, 1-cube model, 2-base, 1a-C-shaped surface part, 1b-main structure, 3-functional mark, 3a-cross mark, 3b-field size mark, 3c-field accuracy mark, 1b-1-first model, 1b-2-second model, 4-first side, 5-second side, 6-first arc groove, 7-third side, 8-second arc groove, 9-fourth side, 10-third arc groove, 11-cylindrical cavity, 2a-first support leg, 2b-second support leg, 2c-main body, 2d-horizontal adjustment knob, 12-groove. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the accompanying drawings. The scope of protection of the present invention is not limited to the following:

[0024] Example 1

[0025] like Figures 1 to 7As shown, the present application provides a phantom device for accelerator performance index testing, including a cubic phantom 1 and a base 2. The cubic phantom has a square through-hole, which provides space for placing plug-ins and ensures that the center of the plug-in coincides with the center of the cubic phantom, providing users with additional performance index testing functions. A rectangular boss is provided on the bottom surface of the cubic phantom, which provides the function of raising the cubic phantom when used alone to avoid direct friction. It also serves as an adapter structure with the base, providing a function of limiting displacement on the base. For example, the base 2 can be provided with a corresponding groove that matches the shape of the rectangular boss, so that the rectangular boss can be embedded in the groove to achieve the positioning of the cubic module. There is no interfering structure within the center of the cubic phantom of the present application within 10*10*10cm. Customized plug-ins are provided to complete specific performance tests according to user needs, such as CT image QA, MRI image QA, image fusion QA, Winston-Lutz measurement of the center of the accelerator mechanical center, etc. The base of the present application can be customized with a fixed positioning device for different treatment beds.

[0026] Preferably, the cube phantom 1 is made of ABS material and has an integrally molded cube structure with square holes running through the front and back for inserting plug-ins. Functional markings can be provided on the cube phantom, including cross marks pointing to the center and offset 1 cm from the center, field size marks indicating the light field size, and field accuracy marks indicating the light field accuracy. These marks are located on the top surface and two side surfaces of the cube, respectively. Low-density marks with image detection functions are embedded inside and can be used for KV / MV imaging. The central through hole of the cube phantom cooperates with the cavities embedded in the eight corners to align the accelerator CBCT. The phantom can be used alone or in conjunction with a base. The base has extendable legs that can be fixed to the treatment bed, ensuring that the position of the phantom relative to the treatment bed remains unchanged during each use. The base also has a spirit level and a level adjustment knob for fine-tuning the phantom level, so that the level of the phantom does not need to be considered during subsequent use. The phantom supports multiple functional plug-ins and can support the completion of various accelerator machine QA-related tasks. Currently, it supports accelerator output measurement, CT value measurement, and Winston Lutz testing. Future plug-ins will be developed based on user needs to accommodate diverse requirements. When using the phantom to test accelerator performance, in addition to testing certain mechanical properties (such as light field accuracy and laser precision), it must be used in conjunction with the "MQC Machine Rapid Testing System" software for automated and rapid machine performance testing. The cube phantom utilizes surface markings and embedded cavities to test accelerator performance. After aligning the laser and light field crosshairs on both sides of the accelerator using a center crosshair, the field size markings on the surface markings can be used to verify light field size and accuracy. The software then captures X-rays and CBCT images to verify the image center and treatment table displacement accuracy. By integrating various plug-ins, all accelerator inspection items can be performed on a single phantom, providing comprehensive coverage for daily, weekly, monthly, and annual accelerator inspections. Specifically, the cube phantom 1 consists of a C-shaped surface element 1a and a main structure 1b. The C-shaped surface part 1a can be nested with the main structure 1b, so that the C-shaped surface part 1a can cover the top surface and two side surfaces of the main structure 1b. Functional marks 3 are provided on the three outer surfaces of the C-shaped surface part 1a, and the functional marks 3 include a cross mark 3a, a field size mark 3b for indicating the light field size, and a field accuracy mark 3c for marking the light field accuracy. The main structure 1b includes a first mold body 1b-1 and a second mold body 1b-2. The second mold body 1b-2 is nested in the first mold body 1b-1. A first arc groove 6 is provided on the first side 4 and the second side 5 of the first mold body 1b-1, a second arc groove 8 is provided on the third side 7 of the first mold body 1b-1, and a third arc groove 10 is provided on the fourth side 9 of the first mold body 1b-1. The first side 4 and the second side 5 are perpendicular to each other, and the second side and the third side are parallel to each other. The third side and the fourth side are perpendicular to each other, and the first side and the fourth side are parallel to each other. For example, as Figure 7As shown, the first side surface can be the top surface, the second side surface can be the left side surface, the third side surface can be the right side surface, and the fourth side surface can be the bottom surface. The first arc groove, the second arc groove, and the third arc groove can be used to indicate the accelerator irradiation direction and angle deviation. A cylindrical cavity 11 is provided at each of the eight vertex corners of the first phantom 1b-1 for accelerator CBCT alignment. The base 2 includes a first leg 2a, a second leg 2b, a body 2c, and a horizontal adjustment knob 2d. The horizontal adjustment knob 2d is threadedly connected to the body 2c, and the level of the base 2 can be adjusted by rotating the horizontal knob 2d. The first leg 2a and the second leg 2b are both hingedly provided on the body 2c, and a groove 12 can be provided on the body 2c for retracting the first leg and the second leg.

[0027] This application can be used to perform the Winston Lutz test, a procedure used to verify the accuracy of the isocenter of a linear accelerator. The specific steps are as follows:

[0028] Preparation: A small metal sphere (e.g., tungsten), representing the planned target, is secured to the linac's treatment bed via a locking mechanism. The sphere's center is positioned at the linac's isocenter, defined by the treatment room laser. This cubic phantom uses a 5mm diameter cavity as the target to accommodate both MV and KV imaging.

[0029] Set up the treatment plan: Create a Winston Lutz plan consisting of multiple non-coplanar fields, typically using a 6 MV photon beam, with a fixed field size for each field.

[0030] Application couch shift: After alignment using the room laser, the couch was intentionally and randomly offset to account for inaccuracies in IGRT software alignment and remote couch motion.

[0031] Imaging and alignment: Use the CBCT scan bedside pointer and manually align the acquired CBCT with the planning CT using the 3D / 3D matching tool, focusing on the tungsten ball and applying the required alignment adjustments through the teletherapy bed movement. The CT value (Computed Tomography Number) is commonly known as the Hounsfield Unit (HU value) and is used to represent the density of different tissues in medical imaging. The CT value is calculated based on the linear attenuation coefficient (μ) of the material and compared with the attenuation coefficient of water. The calculation formula of the CT value is as follows CT value ,in: is the linear attenuation coefficient of the substance being measured. is the linear attenuation coefficient of water. According to this formula, the CT value of water is 0, the CT value of air is close to -1000 HU, and the CT value of bone can exceed +1000 HU.

[0032] Irradiation: The metal ball is irradiated using a linear accelerator. Each field of irradiation is imaged by the electron portal imaging device (EPID) of the linear accelerator, and the distance between the center of each field and the center of the metal ball's shadow is recorded.

[0033] Image analysis: Use image processing software (e.g., Image J or MATLAB-based programs) to analyze the images captured by the EPID and calculate the distance between the center of the metal sphere and the center of the radiation field with an accuracy of approximately 0.1 mm.

[0034] Result evaluation: Evaluate the measurement results to determine whether the deviation of the isocenter is within the acceptable range. Usually, this deviation should be less than 1-1.5 mm to avoid significant dose errors during treatment.

[0035] Adjustment and optimization: If the deviation is found to exceed the threshold, the linear accelerator needs to be adjusted and the test repeated until the accuracy requirements are met.

[0036] Example 2

[0037] This embodiment is a further improvement of embodiment 1, and repeated contents will not be repeated here.

[0038] Preferably, the thickness of the C-shaped surface element 1a is 5 mm, and the distance between the C-shaped surface element 1a and the first phantom 1b-1 can be 5 mm. The second phantom 1b-2 can accommodate a CTQA plug-in or a Winston Lutz test rod plug-in. The CTQA plug-in consists of a cylindrical functional module with a diameter of 12 cm and a height of 10 cm, and a 12*12*20 cm counterweight cube. The cylindrical functional module supports CT scan uniformity measurement and multiple CT value measurement (six material rods with a diameter of 2 cm and a length of 2 cm are evenly distributed around a 6 cm diameter circle). (The functional components can be modified as needed to accommodate various CTQA requirements.) The counterweight cube contains a 10*10*18 cm cavity, supporting CTQA without affecting the mechanical quality assurance (QA) functions of the phantom itself. The Winston Lutz test rod plug-in has a diameter of 1 cm and a total length of 20 cm (the usable length is 10 cm, which can be modified as needed). It has a cube at the end with a length, width, and height of 2 cm. There is a cross mark on the center of the cube surface, and there is a 5mm diameter spherical cavity inside, which can be used for the Winston Lutz accelerator mechanical isocenter and radiation isocenter test.

[0039] Preferably, the top, left, and right surfaces of the C-shaped surface element have crosshairs pointing to the center to assist in aligning the lasers on both sides of the medical accelerator with the crosshairs of the light field, so that the center of the phantom coincides with the mechanical isocenter of the accelerator. The surface of the C-shaped surface element also has 5*5, 10*10, and 15*15 cm light field size frame lines, which, when aligned, accurately indicate the size of the light field opened by the accelerator. The 5*5 cm and 10*10 cm light field size frame lines have 1mm and 2mm wide light field accuracy indicator grooves, respectively. During use, the position of the light field boundary shadow can be used to determine whether the light field progress deviation is less than 1mm or 2mm. The surface of the phantom has a cross mark offset by 1cm from the center to indicate the designated position of the treatment bed movement, which is used to determine the accuracy of the subsequent automatic return of the treatment bed.

[0040] Preferably, the first arc groove, the second arc groove and the third arc groove have arc segments with the same center but different centers. On the KV / MV image, the direction of the accelerator image during shooting (0°, 90°, 180°, 270°) can be judged by the inner and outer positions of the different arc segments, and the angular deviation can be calculated by the center positions of the large and small arcs on the image.

[0041] Preferably, the arcs on all four surfaces are 13 cm from the center (center), avoiding the central 10x10 cm range to prevent interference with central point dose measurement. The arc grooves on all four surfaces have the same width and depth (2 mm wide, 3 mm deep), and the distance between the farthest ends of the arc grooves is 84 mm (within the center hole of the phantom), ensuring clear imaging in accelerator KV or MV imaging. Specifically, the top surface 4 and left side 5 are inscribed with four line segments pointing to the arc center. The arc on the right side 7 is divided into four segments, and the arc on the bottom surface 9 is divided into six segments. These segments serve to discern the angle of incidence of radiation emitted by the accelerator. Specifically, when a ray passes through a surface and its opposite side, due to the perspective effect of near-sightedness, the inner and outer positions of the arcs with line segments and the segmented arcs can be used to determine which surface the ray entered. The angle of incidence can then be calculated based on the difference in the center positions of the two arcs. For example, suppose a ray enters from the top surface 4, passes through the bottom surface 9, and reaches the accelerator EPID flat panel image. Because the accelerator's conical beam output creates a perspective effect where objects appear larger near the accelerator source and smaller far away (the image appears larger closer to the accelerator source), the image clearly shows that the segmented arc on top surface 4 lies outside the segmented arc on bottom surface 9. Furthermore, since the image contains six segmented arcs, the imaging angle can be directly determined from the image to be 0° from top to bottom. Furthermore, by using software to calculate the positions of the arc centers on both surfaces, a more accurate accelerator incident angle can be obtained. Similarly, it is possible to determine whether the imaging angle is 90° (segmented arc outside, four segmented arcs), 180° (segmented arc inside, six segmented arcs), or 270° (segmented arc inside, four segmented arcs).

[0042] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A phantom device for detecting accelerator performance indicators, comprising a cubic phantom (1) arranged on a base (2), characterized in that: The cubic model (1) is configured with a C-shaped surface part (1a) and a main body structure (1b), wherein: The C-shaped surface part (1a) is C-shaped, the main structure (1b) is three-dimensional and nested in the C-shaped surface part (1a), a functional mark (3) is provided on the outer surface of the C-shaped surface part (1a), and an arc groove is provided on the outer surface of the main structure (1b), wherein the functional mark (3) and the arc groove are spaced apart by a set distance; The main structure (1b) comprises a first mold body (1b-1) and a second mold body (1b-2) which are nested with each other. When the second mold body (1b-2) is nested in the first mold body (1b-1), the second mold body (1b-2) is hollow.

2. The phantom device according to claim 1, wherein The functional mark (3) includes a cross mark (3a), a field size mark (3b) and a field accuracy mark (3c), wherein the shape of the field size mark (3b) can be defined by a quadrilateral, and the shapes of the cross mark (3a) and the field accuracy mark (3c) can both be defined by a cross, wherein the center of the cross mark (3a) does not coincide with the center of the field size mark (3b), and the center of the field accuracy mark (3c) coincides with the center of the field size mark (3b).

3. The phantom device according to claim 2, wherein: The arc groove comprises a first arc groove (6), a second arc groove (8) and a third arc groove (10), wherein the first side surface (4) and the second side surface (5) of the first mold body (1b-1) are both provided with the first arc groove (6), the third side surface (7) of the first mold body (1b-1) is provided with the second arc groove (8), and the fourth side surface (9) of the first mold body (1b-1) is provided with the third arc groove (10), wherein the first side surface (4) and the second side surface (5) are perpendicular to each other, the second side surface (5) and the third side surface (7) are parallel to each other, the third side surface (7) and the fourth side surface (9) are perpendicular to each other, and the first side surface (4) and the fourth side surface (9) are parallel to each other.

4. The phantom device according to claim 3, wherein: A cylindrical cavity (11) is provided at each of the eight vertex positions of the first mold body (1b-1).

5. The phantom device according to claim 2, wherein: The thickness of the C-shaped surface part (1a) is 5 mm, and the set distance between the C-shaped surface part (1a) and the first mold body (1b-1) is 5 mm.

6. The phantom device according to claim 5, characterized in that The field size mark (3b) is composed of three light field size frame lines with sizes of 5 cm*5 cm, 10 cm*10 cm, and 15 cm*15 cm, respectively. The center of the cross mark (3a) deviates from the center of the field size mark (3b) by 1 cm.

7. The phantom device according to claim 6, characterized in that The first arc groove, the second arc groove and the third arc groove are all composed of a plurality of different arc groove segments having the same center.

8. The phantom device according to claim 1, wherein: The base (2) comprises a first support leg (2a), a second support leg (2b), a body (2c) and a horizontal adjustment knob (2d); a groove (12) is provided on the body (2c); the first support leg (2a) and the second support leg (2b) are both hinged to the body (2c); the horizontal adjustment knob (2d) is provided on the body (2c); wherein the first support leg (2a) and the second support leg (2b) can be nested in the groove (12).

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