A three-dimensional dose verification phantom for stereotactic radiotherapy

Abstract

This invention discloses a three-dimensional dose verification phantom for stereotactic radiotherapy, comprising a base, a support, and a spherical verification phantom body. The base includes a support mounting slot and a first set of adjusting screws. The support includes a fixing device, a second set of adjusting screws, and the support body. The spherical verification phantom body is composed of two hemispherical phantoms. Each hemispherical phantom includes a probe array slot, a groove, and a locking mechanism. The base is connected to the support body via the support mounting slot. The first set of adjusting screws is located around the base. The fixing device is mounted on the support body. The second set of adjusting screws is mounted on the fixing device. The locking mechanism is located on the side of the hemispherical phantom. The groove is located on the circular surface of the hemispherical phantom. The probe array slot is located inside the hemispherical phantom. This invention enables simultaneous dose verification of multiple target areas in three-dimensional space. This invention can be widely applied in the field of radiotherapy quality control technology.

Description

Technical Field

[0001] This invention relates to the field of radiotherapy quality control technology, and in particular to a three-dimensional dose verification phantom for stereotactic radiotherapy. Background Technology

[0002] Stereotactic radiotherapy (SRT) is a specialized treatment technique primarily used for small brain tumors. Due to its significant minimally invasive nature, high efficacy, and low cost, it has gradually become a core treatment option for brain metastases. SRT typically employs multi-field or multi-arc focusing techniques to deliver extremely high doses within the target area per fraction, achieving the goal of killing the tumor with a single or fewer fractions. Because this technique involves large fractional doses and extremely steep dose drops at the field boundaries, any dosimetric deviation can cause serious radiotherapy accidents for the patient. Therefore, special quality control is required to ensure the safety and quality of stereotactic radiotherapy.

[0003] Currently, in addition to routine quality control of the equipment itself, the most important aspect of quality control for stereotactic radiotherapy is the quality control of each individualized treatment plan. Common practices include: visually comparing the corresponding optical field with a printed two-dimensional digitally reconstructed shape map of the radiation field in the treatment room to confirm the accuracy of the radiation field; measuring the actual point dose using a small-volume ionization chamber in a spherical or simulated human head phantom to assess the dose accuracy of the plan; and measuring the actual two-dimensional dose distribution using a small-area dose film or a detector array in a spherical or simulated human head phantom and performing Gamma analysis to assess the accuracy of the single-plane dose.

[0004] However, current clinical dose verification phantoms and methods for stereotactic radiotherapy plans are limited to point dose or single-plane dose verification, and do not achieve three-dimensional dose verification. Existing three-dimensional dose verification phantoms cannot simultaneously verify the dose of multiple target areas, and cannot perform synchronous dose verification when there are multiple small-volume tumors in stereotactic radiotherapy. Summary of the Invention

[0005] To address the aforementioned technical problems, the objective of this invention is to provide a three-dimensional dose verification phantom for stereotactic radiotherapy, capable of simultaneously verifying the dose of multiple target regions in three-dimensional space, thereby enabling a more comprehensive scientific assessment of the feasibility of stereotactic radiotherapy plans.

[0006] The technical solution adopted in this invention is: a three-dimensional dose verification phantom for stereotactic radiotherapy, comprising a base, a support, and a spherical verification phantom body, wherein:

[0007] The base includes a bracket mounting slot and a first set of adjusting screws;

[0008] The bracket includes a fixing device, a second adjusting screw group, and a bracket body;

[0009] The spherical verification phantom body is composed of two hemispherical phantoms;

[0010] The hemispherical mold includes a probe plate array slot, grooves, and bayonet openings;

[0011] The base is connected to the support body via a bracket mounting slot; the first adjusting screw group is located around the base and is used to adjust the base's levelness; the fixing device is installed on the support body and is used to fix the position of the spherical verification mold body; the second adjusting screw group is installed on the fixing device and is used to adjust the position of the fixing device; the bayonet is located on the side of the hemispherical mold body and is used to lock the hemispherical mold body; the concave and convex grooves are provided on the circular surface of the hemispherical mold body and are used for the aligned installation of the two hemispherical mold bodies; the detector plate array slot is located inside the hemispherical mold body and is used to install the detector plate array.

[0012] Furthermore, the three-dimensional dose verification phantom for stereotactic radiotherapy also includes a probe array calibration module for calibrating the probe array response consistency and absolute dose calibration.

[0013] Furthermore, the base also includes a universal bubble level, which is located on the upper surface of the base and is used to assess the levelness of the base.

[0014] Furthermore, the fixing device includes a hollow fixing device and an auxiliary fixing device, wherein:

[0015] The hollow fixing device is installed on the main body of the bracket and is used to fix the auxiliary fixing device;

[0016] The second set of adjusting screws is installed on the hollow fixing device and is used to adjust the position of the auxiliary fixing device;

[0017] The auxiliary fixing device is connected to the main body of the spherical verification mold and is used to fix the position of the main body of the spherical verification mold.

[0018] Furthermore, the spherical verification phantom is also provided with a first mark and a second mark, wherein:

[0019] The first mark is located on both sides of the spherical mold and is used to align with the placement of the laser lines on both sides;

[0020] The second mark is located on the top of the spherical phantom and is used to align with the crosshairs of the light field or the center laser line.

[0021] Furthermore, the probe array slots are in a star shape, including a horizontal main board slot, two vertical sub-board slots, and four wing plate slots.

[0022] This optimization process achieves full coverage of the spatial structure, avoiding the drawback of dose blind spots present in current single-plane systems.

[0023] Furthermore, the operation method of the three-dimensional dose verification phantom for stereotactic radiotherapy includes the following steps:

[0024] Perform response consistency calibration and absolute dose calibration on the detector array;

[0025] The probe array, after response consistency calibration and absolute dose calibration, is installed into the three-dimensional dose verification phantom and its position is adjusted to obtain the three-dimensional dose verification phantom after positioning.

[0026] A stereotactic radiotherapy plan was executed within a three-dimensional dose verification phantom after positioning to obtain the actual three-dimensional dose distribution.

[0027] The stereotactic radiotherapy plan was transferred to the CT images of the three-dimensional dose verification phantom after positioning, and the three-dimensional dose distribution of the plan was derived.

[0028] The actual three-dimensional dose distribution and the planned three-dimensional dose distribution were calculated and analyzed to obtain the overall plan validation pass rate.

[0029] Furthermore, the step of installing the detector array after response consistency calibration and absolute dose calibration into the three-dimensional dose verification phantom and adjusting its position to obtain the positioned three-dimensional dose verification phantom specifically includes:

[0030] Rotate the screws of the first adjusting screw group to adjust the bubble in the universal bubble level so that it is centered.

[0031] Rotate the screws of the second adjusting screw group to adjust the auxiliary fixing device and the main body of the spherical verification mold to be in a horizontal position;

[0032] The spherical verification phantom is adjusted by moving the bed to ensure that the first mark line is aligned with the laser lines on both sides, the second mark line is aligned with the center laser line or the crosshair of the optical field, and the spherical verification phantom is located at the isocenter of the accelerator.

[0033] Furthermore, the three-dimensional dose verification phantom supports both a planned verification method based on direct measurement using a probe plate and a planned verification method based on a three-dimensional dose reconstruction algorithm using measured dose.

[0034] Furthermore, the planning and verification method based on the three-dimensional dose reconstruction algorithm for measured dose includes the following steps:

[0035] The beam direction is determined based on the dose distribution characteristics and spatial structure, and the multi-planar doses with dose distribution are sorted based on the beam direction to obtain the scanning order;

[0036] The maximum dose of each plane is obtained by scanning the dose of each plane according to the scanning sequence.

[0037] Based on the maximum dose, different reference doses are set, and scans are performed to obtain several geometric centers that are higher than the reference dose range;

[0038] The average geometric center point is obtained by averaging the coordinates of several geometric centers.

[0039] By performing a linear fit on the average geometric center point, the straight line equation of the beam centerline is obtained;

[0040] The frame angle and virtual source coordinates are solved based on the linear equation of the beam centerline and the location of the virtual source.

[0041] The dose at each point on the ray is calculated based on the virtual source coordinates and the dose of each plane along the ray incident direction.

[0042] The reconstructed three-dimensional dose for that frame is formed based on the dose at each point on each incident beam.

[0043] The three-dimensional doses corresponding to all frames are reconstructed and superimposed to form the final three-dimensional doses within the phantom.

[0044] The beneficial effects of this invention are as follows: The novel star-shaped structure design achieves full coverage in three-dimensional space, avoiding the difficulty in measuring dose in non-central or multi-target areas; simultaneous measurement of multiple target areas enables simultaneous dose measurement and verification analysis of multiple brain metastases; the detachable design of the dual-hemispherical phantom allows for convenient disassembly of the probe array; the probe array calibration module simplifies the calibration methods for relative response consistency and absolute dose; the star-shaped structure design and spherical phantom body design allow for more probes and smaller spacing, enabling more and denser dose measurements in space; and the measurement-based three-dimensional dose reconstruction provides more dosimetric information for stereotactic radiotherapy planning evaluation. Attached Figure Description

[0045] Figure 1 This is a structural diagram of a three-dimensional dose verification phantom for stereotactic radiotherapy according to the present invention;

[0046] Figure 2 This is a schematic diagram of the base and support structure of a three-dimensional dose verification phantom for stereotactic radiotherapy according to the present invention;

[0047] Figure 3 This is a schematic diagram of the main structure of a spherical verification phantom for a three-dimensional dose verification phantom used in stereotactic radiotherapy according to the present invention;

[0048] Figure 4 This is a schematic diagram of a probe array for a three-dimensional dose verification phantom used in stereotactic radiotherapy according to the present invention;

[0049] Figure 5 This is a schematic diagram of the detector array calibration module structure of a three-dimensional dose verification phantom for stereotactic radiotherapy according to the present invention;

[0050] Figure Descriptions: 1. Base; 2. Bracket; 3. Spherical Verification Phantom Body; 4. Hollow Fixing Device; 5. Auxiliary Fixing Device; 6. First Screw; 7. Universal Bubble Level; 8. Bracket Mounting Slot; 9. Bracket Body; 10. Second Screw; 11. Bayonet; 12. Truncation; 13. Detector Plate Array Slot; 14. Horizontal Main Board Slot; 15. Vertical Sub-Board Slot; 16. Wing Plate Slot; 17. First Mark; 18. Second Mark; A. Main Board; G. Sub-Board; B. Wing Plate. Detailed Implementation

[0051] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only for ease of explanation and do not limit the order of the steps. The execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.

[0052] Reference Figure 1 A three-dimensional dose verification phantom for stereotactic radiotherapy, comprising a base 1, a support 2, and a spherical verification phantom body 3, wherein:

[0053] Refer to the base structure diagram Figure 2 (a) The base 1 is made of high-density polyethylene resin and adopts a large-area fan-shaped structure design, which balances the overall weight, stability, and aesthetics of the equipment. The base includes a bracket mounting slot, a first adjusting screw group, and a universal bubble level. The base is connected to the bracket body through the bracket mounting slot. The first adjusting screw group is located around the base and has three adjusting screw holes, located at both ends of the base chord and the midpoint of the arc, respectively, for adjusting the levelness of the base. The universal bubble level is a circular universal bubble level, located at the center of mass on the upper surface of the base, for assessing the levelness of the base. When the bubble of the circular universal bubble level is in the center of the circle, it indicates that the base is level.

[0054] Reference to the side view of the bracket Figure 2 (b) and the three-dimensional support structure Figure 2(c) The bracket is made of high-density polyethylene resin. The bracket includes a hollow fixing device, an auxiliary fixing device, a second adjusting screw group, and a bracket body. The upper end of the bracket body has a circular hole for installing the hollow fixing device, and the hollow fixing device is in close contact with the circular hole. The hollow fixing device adopts a cylindrical hollow design for fixing the auxiliary fixing device. The second adjusting screw group is installed on the hollow fixing device and is installed at the left and right ends of the hollow fixing device. There is an adjusting screw on the upper, lower, left, and right surfaces of the left and right ends of the hollow fixing device for adjusting the position of the auxiliary fixing device. The auxiliary fixing device is cylindrical with one end ground smooth. The other end of the auxiliary fixing device is connected to the spherical verification mold body for fixing the position of the spherical verification mold body. The ground smooth end of the auxiliary fixing device passes through the hollow fixing device and is fixed inside the hollow fixing device by the second adjusting screw group.

[0055] Side view of the main body of the spherical verification phantom Figure 3 (a) and (c) a sagittal view of the main body of the spherical verification phantom, wherein the surface of the main body of the spherical verification phantom has a circular hole for connecting with an auxiliary fixing device to fix the main body of the spherical verification phantom; there is also a circular metal ring inside the hole for embedding and fixing with the auxiliary fixing device to prevent deviation and shaking after connection.

[0056] Furthermore, referring to the side view of the internal structure of the spherical verification phantom body. Figure 3 (b) Perspective of the three-dimensional structure of the main body of the spherical verification phantom Figure 3 (d) The sphere has a diameter of 20cm and contains a probe array slot inside; the probe array slot is in the shape of a cross and includes a horizontal main board slot, two vertical sub-board slots and four wing plate slots for installing the probe array.

[0057] Furthermore, referring to the hemispherical phantom mechanism of the spherical verification phantom body. Figure 3 (e) The spherical verification mold body is composed of two hemispherical molds; the hemispherical mold includes grooves and slots; the slots are provided on the side of the hemispherical mold for locking the hemispherical mold; the grooves are provided on the circular surface of the hemispherical mold for precise alignment and installation of the two hemispheres.

[0058] Furthermore, refer to Figure 1 The spherical verification mold is also provided with a first mark and a second mark; in this embodiment, both the first mark and the second mark are cross lines as marks, but they are not limited to cross lines. They can also be T-shaped marks, rectangular marks, dot marks, etc., which can achieve this function; the first mark is located on both sides of the spherical mold and is used to align with the laser lines on both sides; the second mark is located on the top of the spherical mold and is used to align with the central laser line or the cross line of the light field.

[0059] Furthermore, refer to Figure 4 The detector array comprises a main board, two sub-boards, and four wing plates; (Refer to the wing plate structure) Figure 4 (a) The wing plate has dimensions of 5cm × 13cm; refer to the main board structure. Figure 4 (b) The mainboard size is 13cm × 13cm; refer to the sub-board structure Figure 4 (c) The size of the sub-plate is 6cm×13cm; the probe spacing in the detector array is 0.5cm.

[0060] Furthermore, refer to Figure 5 The three-dimensional dose verification phantom also includes a detector array calibration module, used for calibrating the detector array response consistency and absolute dose calibration; refer to the schematic diagram of the detector array calibration module structure. Figure 5 (a) Place the main board, sub-board, and wing plate according to position 5(a); refer to the assembly diagram of the detector array calibration module. Figure 5 (b) After placement, place a 2cm cover plate on the detector array calibration module slot where the detector array plate is placed, and then the detector plate response consistency calibration and absolute dose calibration can be performed.

[0061] The operation method of using the above-mentioned three-dimensional dose verification phantom for stereotactic radiotherapy includes the following steps:

[0062] S1. Perform response consistency calibration and absolute dose calibration on the detector array;

[0063] Specifically, the spherical phantom is disassembled, all the probe plates are removed, and placed in the corresponding positions in the probe plate calibration phantom as required. The cover plate is then modified to perform calibration and absolute dose calibration for response consistency.

[0064] S2. Install the detector array after response consistency calibration and absolute dose calibration into the three-dimensional dose verification phantom, and adjust its position to obtain the three-dimensional dose verification phantom after positioning.

[0065] Specifically, the detector array, after response consistency calibration and absolute dose scaling, is first installed onto the three-dimensional dose verification phantom and placed on the treatment bed. The screws of the first adjusting screw group are rotated and adjusted until the bubble in the circular universal bubble level is in the center of the circle, indicating that the base has been modulated into a horizontal state. Next, the screws of the second adjusting screw group are rotated and adjusted to ensure that the auxiliary fixing device and the main body of the spherical verification phantom are in a horizontal position. Finally, the spherical verification phantom is moved and adjusted to ensure that the first mark is aligned with the laser lines on both sides of the phantom, the second mark is aligned with the central laser line or the crosshair of the optical field, and the spherical verification phantom is located at the isocenter of the accelerator, thus obtaining the positioned three-dimensional dose verification phantom. If necessary, registration and confirmation of the positioning can also be performed using CBCT scanning.

[0066] S3. Execute the stereotactic radiotherapy plan within the three-dimensional dose verification phantom after positioning to obtain the actual three-dimensional dose distribution;

[0067] S4. Transfer the treatment plan to be evaluated to the CT images of the three-dimensional dose verification phantom after positioning, and derive the three-dimensional dose distribution of the plan;

[0068] Specifically, the treatment plan to be evaluated is transferred to the CT image of the three-dimensional dose verification phantom after positioning. By setting the center of the three-dimensional dose verification phantom as the center of the plan, the planned three-dimensional dose distribution of the evaluated plan in the three-dimensional dose verification phantom is calculated.

[0069] S5. Calculate and analyze the actual three-dimensional dose distribution and the planned three-dimensional dose distribution to obtain the overall plan verification pass rate.

[0070] Specifically, plan validation essentially assesses the theoretical dose planned by the planning system based on measured actual doses. Gamma analysis, on the other hand, calculates the Gamma value for each probe relative to the doses at all planned points within a certain range in the surrounding three-dimensional space, assigning the minimum Gamma value to that location. Therefore, each measurement point corresponds to a minimum Gamma value, the number of which equals the total number of detectors. The specific formula for calculating the Gamma value is as follows:

[0071]

[0072] Where γ represents the Gamma value, Δr0 and ΔD0 represent the standard values ​​for calculating the Gamma value, which are 3 mm and 3% respectively, Δr represents the three-dimensional distance between the planned dose point and the actual dose point under the aligned coordinate system, in mm, and ΔD represents the percentage dose difference between the planned dose point and the actual dose point.

[0073] The percentage of Gamma values ​​between 0 and 1 to the percentage of non--1 values ​​is the Gamma pass rate. Typically, when calculating Gamma values, in addition to selecting the calculation standards Δr and ΔD, a dose threshold also needs to be determined, usually 10%. This means that points where the measured dose is less than 10% of the maximum dose are not included in the Gamma value calculation; they are directly assigned a value of -1 and are not included in the Gamma pass rate calculation.

[0074] After analyzing and calculating the Gamma pass rate, the planning system also provides a function for averaging the Gamma value. This involves first setting the calculation standards Δr and ΔD, and then setting a dose threshold to calculate the average Gamma value. By continuously changing the dose threshold, the average Gamma value under different threshold conditions is obtained, thereby analyzing the degree of dose consistency across different dose level ranges. The formula for calculating the average Gamma value is as follows:

[0075]

[0076] Where, γ mean The value represents the average Gamma value, N represents the total number of doses at the analysis points, and γ represents the average Gamma value. i This represents the i-th Gamma value.

[0077] Specific embodiments of the present invention support both a planning and verification method based on direct measurement using a probe and a planning and verification method based on a three-dimensional dose reconstruction algorithm using measured dose.

[0078] The planning verification method based on direct measurement using probes can directly derive a three-dimensional data matrix in point dose form as the theoretical dose distribution. The position of each probe is fixed; therefore, the spatial coordinates of the dose measured by each probe on each probe are also fixed, which can be solved mathematically and pre-installed in the system. The planned three-dimensional dose distribution calculated by the planning system is output in RTdose format (Dicom), primarily as a three-dimensional data matrix in point dose form. The header information includes the origin and the spacing between point doses. Further dosimetric analysis is then performed directly using this three-dimensional data matrix.

[0079] The core of the plan verification method based on the measured dose 3D dose reconstruction algorithm is the back-projection 3D dose reconstruction method based on the measured dose. Measurement data is acquired at a frequency of 1 frame / second. In principle, the dose distribution of each frame corresponds to a gantry angle of an accelerator. Our novel gantry angle solving algorithm based on multi-plane dose distribution can accurately calculate the gantry angle corresponding to that frame. Therefore, given the solved gantry angle, when a beam from a certain subfield irradiates the phantom, it typically passes through multiple detectors, forming multiple planar dose distributions. Since the label and position of each detector are fixed, the spatial coordinates of the two-dimensional dose distribution are also known. Then, the 3D dose distribution is reconstructed in the phantom using the measured multi-plane dose distribution. This method is applied sequentially using a for loop for all valid frames with acquired doses, and the 3D doses are accumulated, ultimately obtaining the measurement-reconstructed 3D dose distribution corresponding to the entire plan, which is then further used for dosimetric analysis.

[0080] The three-dimensional dose reconstruction algorithm based on the measurement of multi-plane dose distribution and virtual source coordinates includes the following steps:

[0081] SS1. Based on the dose distribution characteristics and spatial structure, determine the approximate direction of the beam and sort the multi-plane doses with dose distribution according to the incident direction;

[0082] SS2. Following the above order, scan the dose of each plane to obtain the maximum dose Dmax of each plane;

[0083] SS3. Within this plane range, perform a scan, set the reference dose to 90% of the Dmax dose value, and solve for the geometric center Center(1, x, y, z) for the range where the dose is greater than the reference dose.

[0084] SS4. Based on the method described in SS3, the reference dose is set from 80% Dmax to 10% Dmax, and multiple geometric center points Center(i, x, y, z) are obtained by scanning calculation.

[0085] SS5. Average the coordinates of the multiple geometric center points Center(i, x, y, z) to obtain a more accurate geometric center point CenterA(1, x, y, z).

[0086] SS6. Repeat the methods in SS2-SS5 to solve for the corresponding mean geometric center CenterA(i, x, y, z) for each plane with dose distribution.

[0087] SS7. Based on these average geometric centers, perform linear fitting to obtain the equation of the straight line representing the beam centerline: F(x,y,z)=0;

[0088] SS8. Set the accelerator's rotation radius to 100cm, and position its virtual beam source on the spherical x-axis. 2 +y 2 +z 2 =100 2 By solving the linear equation fitted to step SS7, the virtual source coordinates (X0, Y0, Z0) of the gantry angle corresponding to the dose in that frame can be obtained.

[0089] SS9. Given the virtual source coordinates (X0, Y0, Z0) corresponding to the dose of this frame and the dose of each plane in the incident direction, the dose D(x, y, z) of each point on the ray is calculated by tracing the incident ray and based on the inverse square distance relationship and the attenuation relationship.

[0090] SS10. Based on the method described in (9) above, the dose D(x,y,z) at each point on each incident ray beam is calculated sequentially to form the reconstructed three-dimensional dose D(X,Y,Z) corresponding to the frame.

[0091] SS11. Following the methods described in SS1-SS10, the three-dimensional doses corresponding to all frames are reconstructed and superimposed sequentially to form the final three-dimensional doses within the phantom.

[0092] When using the planning and validation method based on the three-dimensional dose reconstruction algorithm of measured dose, three-dimensional Gamma analysis can be used, or Gamma analysis can be performed within each structure after importing the structure file, as well as DVH analysis of each anatomical structure.

[0093] The contents of the above device embodiments are all applicable to the present method embodiments. The specific functions implemented in the present method embodiments are the same as those in the above device embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0094] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A three-dimensional dose verification phantom for stereotactic radiotherapy, characterized in that, Includes a base, a support frame, and a spherical verification phantom body, wherein: The base includes a bracket mounting slot and a first set of adjusting screws; The bracket includes a fixing device, a second adjusting screw group, and a bracket body; The spherical verification phantom body is composed of two hemispherical phantoms; The hemispherical mold includes a probe plate array slot, grooves, and bayonet openings; The base is connected to the support body via a bracket mounting slot; the first adjusting screw group is located around the base and is used to adjust the base's levelness; the fixing device is installed on the support body and is used to fix the position of the spherical verification mold body; the second adjusting screw group is installed on the fixing device and is used to adjust the position of the fixing device; the bayonet is located on the side of the hemispherical mold body and is used to lock the hemispherical mold body; the concave and convex grooves are provided on the circular surface of the hemispherical mold body and are used for the aligned installation of two hemispherical mold bodies; the detector plate array slot is located inside the hemispherical mold body and is used to install the detector plate array; The probe board array slots are in a star shape, including one horizontal main board slot, two vertical sub-board slots and four wing plate slots; The detector array includes a main board, two sub-boards, and four wing boards.

2. The three-dimensional dose verification phantom for stereotactic radiotherapy according to claim 1, characterized in that, It also includes a detector array calibration module, which is used to perform detector response consistency calibration and absolute dose calibration on the detector array.

3. The three-dimensional dose verification phantom for stereotactic radiotherapy according to claim 1, characterized in that, The base also includes a universal bubble level, which is located on the upper surface of the base and is used to assess the levelness of the base.

4. The three-dimensional dose verification phantom for stereotactic radiotherapy according to claim 1, characterized in that, The fixing device includes a hollow fixing device and an auxiliary fixing device, wherein: The hollow fixing device is installed on the main body of the bracket and is used to fix the auxiliary fixing device; The second set of adjusting screws is installed on the hollow fixing device and is used to adjust the position of the auxiliary fixing device; The auxiliary fixing device is connected to the main body of the spherical verification mold and is used to fix the position of the main body of the spherical verification mold.

5. The three-dimensional dose verification phantom for stereotactic radiotherapy according to claim 1, characterized in that, The spherical verification phantom is also provided with a first mark and a second mark, wherein: The first mark is located on both sides of the spherical mold and is used to align with the placement of the laser lines on both sides; The second mark is located on the top of the spherical phantom and is used to align with the crosshairs of the light field or the center laser line.

6. A three-dimensional dose verification phantom for stereotactic radiotherapy according to any one of claims 1-5, characterized in that, The operation method includes the following steps: Perform response consistency calibration and absolute dose calibration on the detector array; The probe array, after response consistency calibration and absolute dose calibration, is installed into the three-dimensional dose verification phantom and its position is adjusted to obtain the three-dimensional dose verification phantom after positioning. A stereotactic radiotherapy plan was executed within a three-dimensional dose verification phantom after positioning to obtain the actual three-dimensional dose distribution. The stereotactic radiotherapy plan was transferred to the CT images of the three-dimensional dose verification phantom after positioning, and the three-dimensional dose distribution of the plan was derived. The actual three-dimensional dose distribution and the planned three-dimensional dose distribution were calculated and analyzed to obtain the overall plan validation pass rate.

7. A three-dimensional dose verification phantom for stereotactic radiotherapy according to claim 6, characterized in that, The step of installing the probe array after response consistency calibration and absolute dose calibration into the three-dimensional dose verification phantom and adjusting its position to obtain the positioned three-dimensional dose verification phantom specifically includes: Rotate the screws of the first adjusting screw group to adjust the bubble in the universal bubble level so that it is centered. Rotate the screws of the second adjusting screw group to adjust the auxiliary fixing device and the main body of the spherical verification mold to be in a horizontal position; The spherical verification phantom is adjusted by moving the bed to ensure that the first mark line is aligned with the laser lines on both sides, the second mark line is aligned with the center laser line or the crosshair of the optical field, and the spherical verification phantom is located at the isocenter of the accelerator.

8. A three-dimensional dose verification phantom for stereotactic radiotherapy according to claim 1, characterized in that, The three-dimensional dose verification phantom supports both the planning and verification method based on direct measurement using a probe and the planning and verification method based on a three-dimensional dose reconstruction algorithm based on measured dose.

9. A three-dimensional dose verification phantom for stereotactic radiotherapy according to claim 8, characterized in that, The planning and validation method based on the three-dimensional dose reconstruction algorithm for measured dose includes the following steps: The beam direction is determined based on the dose distribution characteristics and spatial structure, and the multi-planar doses with dose distribution are sorted based on the beam direction to obtain the scanning order; The maximum dose of each plane is obtained by scanning the dose of each plane according to the scanning sequence. Based on the maximum dose, different reference doses are set, and scans are performed to obtain several geometric centers that are higher than the reference dose range; The average geometric center point is obtained by averaging the coordinates of several geometric centers. By performing a linear fit on the average geometric center point, the straight line equation of the beam centerline is obtained; The frame angle and virtual source coordinates are solved based on the linear equation of the beam centerline and the location of the virtual source. The dose at each point on the incident ray is calculated based on the virtual source coordinates and the ray incident direction of each plane dose. The reconstructed three-dimensional dose for the current frame is formed based on the dose at each point on each incident beam. The three-dimensional doses corresponding to all frames are reconstructed and superimposed to form the final three-dimensional doses within the phantom.

Images