Optimization method for stereotactic center ablation treatment parameters of space division radiotherapy

Abstract

The invention discloses an optimization method for stereotactic center ablation treatment parameters of space division radiotherapy, and belongs to the technical field of radiotherapy. The method specifically comprises the following steps of 1, constructing a parameter automatic optimization calculation unit, 2, obtaining DICOM data, and 3, selecting a sketching structure to obtain a sketching area. 4, self-defining a middle hot area generation parameter; 5, importing the middle hot area generation parameter obtained in the previous step into a radiotherapy planning system by a parameter automatic optimization calculation unit; sixthly, the radiotherapy plan is designed according to the method of only irradiating the volume of the middle hot area, the dosage of surrounding normal tissue is controlled according to the design proportion, and the radiotherapy plan is output; and the treatment plan is transmitted to the treatment equipment for treatment. According to the optimization method for the stereotactic center ablation treatment parameters of the space division radiotherapy, the accuracy of hot area design can be improved, clinical use of the SCART technology is standardized, and the efficiency and quality of stereotactic center ablation irradiation sketching are improved.

Description

Technical Field

[0001] The present invention specifically relates to an optimization method for the parameters of stereotactic central ablation therapy in space - fractionated radiotherapy, belonging to the technical field of radiotherapy. Background Art

[0002] Space - fractionated radiotherapy (SFRT) proposes the concept of using large doses in few fractions to irradiate only part of the tumor. It provides more creative and complementary applications in the field of controlling tumors while ensuring the dose tolerance of surrounding normal tissues. The GRID therapy and Lattice therapy of SFRT have been proven to have advantages in the environment of large tumors. GRID and Lattice intend to generate multiple hot spots or heat islands within the large tumor. These hot spots can not only directly kill cancer cells but also trigger biological effects such as SBRT. Since GRID and Lattice limit the dose to surrounding tissues, the side effects are also small. However, their designs are complex and require a large amount of labor in planning and treating GRID and Lattice. More importantly, generating multiple hot spots and adapting to large tumors may limit the size of each hot spot, and compared with the volume of the large tumor, the total volume of the hot regions (strip - shaped or island - shaped) is small. Among them, the core principle of SCART is similar to that of GRID and Lattice. The purpose of SCART is to stereotactically irradiate a partial target volume (hot spot) located at the center of the large tumor target with an ablation dose (15 Gy or higher), and the dose rapidly drops from the edge of the hot spot to a low dose (3 Gy or lower) at the edge of the tumor volume. The goal is to irradiate the largest possible volume with the ablation dose while keeping the dose at the tumor edge at a low dose. SCART has the following advantages: (1) Only one hot spot in the middle is designed, which is easier to achieve using modern radiotherapy techniques and has a shorter treatment time; (2) The volume of the hot region is larger, about 30 times and 500 times that of Grid and Lattice respectively, and the efficiency is significantly increased. However, the treatment effect of SCART has a great correlation with the volume of the hot region. A higher hot - region volume also brings higher treatment risks and side effects. How to design the volume of the middle hot region and how to control the dose fall outside the hot region to protect normal tissues are the key factors for realizing SCART. Summary of the Invention

[0003] To solve the above problems, the present invention proposes an optimization method for the parameters of stereotactic central ablation therapy in space - fractionated radiotherapy. By using a parameter automatic optimization calculation unit for parameter optimization calculation, it not only improves the accuracy of hot - region design but also standardizes the clinical use of SCART technology, and can improve the efficiency and quality of stereotactic central ablation irradiation delineation.

[0004] The optimization method for the parameters of stereotactic central ablation therapy in space - fractionated radiotherapy of the present invention is as follows: Step 1: Construct an automatic parameter optimization calculation unit, which is respectively connected to the image storage system and the radiotherapy system of a hospital or a clinic; Step 2: DICOM data acquisition. First, data scraping is performed. The automatic parameter optimization calculation unit automatically extracts the DICOM files of patients through the image storage system. The automatic parameter optimization calculation unit supports batch import of image data. Then, the automatic optimization calculation unit automatically parses the DICOM files. The automatic optimization calculation unit parses the image data and the metadata related to the image data in the DICOM files. After confirming that all data is accurately read, the DICOM data acquisition is completed; Step 3: Structure delineation selection. The automatic parameter optimization calculation unit automatically delineates the DICOM data, selects the structures or regions to be delineated, differentiates the tumor regions, tissue organs or other associated regions, and obtains the delineated regions; Step 4: Customize the parameters for generating the intermediate hot zone. The automatic parameter optimization calculation unit selects the intermediate hot zone according to the delineated regions obtained in the third step. By default, the intermediate hot zone is the tumor region. Set the dose gradient, size, and shape parameters of the high-dose region to meet the treatment requirements of different types of tumors. Generate the parameters for generating the intermediate hot zone according to the ratio calculated by the prescription requirements and the mathematical model; Step 5: The automatic parameter optimization calculation unit imports the parameters for generating the intermediate hot zone obtained in the previous step into the radiotherapy planning system; Step 6: The radiotherapy planning system designs the plan by the method of irradiating only the volume of the intermediate hot zone, controls the dose of the surrounding normal tissues according to the designed ratio, and outputs the radiotherapy plan; and transmits the treatment plan to the treatment device for treatment.

[0005] Further, the design ratio of the radiotherapy plan is that the core irradiation dose is 3 to 8 times the boundary irradiation dose.

[0006] Further, the image data includes pixel data, resolution, slice thickness, and scanning parameters; the metadata includes patient information and examination date.

[0007] Further, the process of generating the parameters for generating the intermediate hot zone according to the prescription requirements and the mathematical model is as follows: 1. The automatic parameter optimization calculation unit obtains the known definitions and initial conditions: 1.1 Input data: GTVslices ∈ Rn×3, containing the coordinates of points (x1, y1, z1); 1.2 Output data: SCARTslices ∈ Rn×3, new coordinate points (x2, y2, z1); 1.3 Parameters: ogapFeet: offset parameter; oshrinkpercentage: shrinkage ratio; Main loop: iterate over the range k ∈ [1 + gapFeet, j + gapFeet]; 2. Then perform initial point transformation and calculate the centroid: 2.1 Extract the point set of the middle hot zone - slice: GTVslices = {(x1, y1, z1)}; 2.2 Calculate the centroid of the polygon: (Xorigin, Yorigin) = centroid(polyshape(x1, y1)); 2.3 Translate the point coordinates to the centroid: xshift = x1 - Xorigin, yshift = y1 - Yorigin; 3. Convert to polar coordinates and optimize the centroid: 3.1 Convert to polar coordinates: (θ, ρ) = cart2pol(xshift, yshift); 3.2 Loop 360 times to adjust the centroid: First, find the current minimum and maximum radius directions: ρmin = min(ρ), θmin = θ(index(ρmin)); θmax = θmin + π, ρmax = ρ(index(min(θ - θmax))); Second, adjust the centroid according to the ρ gap: Δρ = 0.01(ρmax - (ρmax + ρmin) / 2); New centroid position: (Xorigin, Yorigin) ← (Xorigin, Yorigin) + pol2cart(θmax, Δρ); Then, update xshift, yshift, θ, ρ; 4. Clip the radius: Limit the radius ρ of all points: ρ(t) = {0, if ρ(t) ≤ 20 mm, ρ(t), otherwise}; 5. Scale the radius: Scale ρ ← ρ * shrinkpercentage; 6. Convert back to Cartesian coordinates: Convert the polar coordinates obtained in the previous step to Cartesian coordinates: (x2, y2) = pol2cart(θ, ρ); 7. Translate back to the original centroid position: x2 ← x2 + Xorigin, y2 ← y2 + Yorigin; 8. Construct the output slice: SCARTslices = {(x2, y2, z1)}; 9. Storage result: SCARTk-gapFeet,1 = SCARTslices.

[0008] Compared with the prior art, the optimization method of the stereotactic central ablation treatment parameters for space-fractionated radiotherapy of the present invention uses a parameter automatic optimization calculation unit to perform parameter optimization calculation, which not only improves the accuracy of hot zone design, but also standardizes the clinical use of the SCART technology. The intermediate hot zone generation parameters are generated according to the prescription requirements and the ratio calculated by the mathematical model, and the ratio of the volume and diameter of the intermediate hot zone (STV) to the volume of the entire treatment target area is simulated, so as to irradiate only the intermediate hot zone and no longer irradiate the entire tumor volume, making the dose drop faster and the dose of the surrounding normal tissues lower; it can improve the efficiency and quality of stereotactic central ablation irradiation delineation, improve the treatment effect and greatly reduce the side effects of radiotherapy. Brief Description of the Drawings

[0009] Figure 1 It is a schematic workflow diagram of the optimization method of the stereotactic central ablation treatment parameters for space-fractionated radiotherapy of the present invention.

[0010] Figure 2 It is a schematic diagram of the ablation treatment state after ASCART optimization and the existing ASCART ablation treatment state of the present invention.

[0011] Figure 3 It is a dosimetric distribution generated by the Grid of the present invention on a case and the generated hot zone volume maps respectively.

[0012] Figure 4 It is a dosimetric distribution generated by the Lattice of the present invention on a case and the generated hot zone volume maps respectively.

[0013] Figure 5 It is a dosimetric distribution generated by the SCART of the present invention on a case and the generated hot zone volume maps respectively. Detailed Description of the Invention

[0014] Example 1: Such as Figures 1 to 5 The optimization method of the stereotactic central ablation treatment parameters for space-fractionated radiotherapy shown, the method is specifically as follows: In the first step, a parameter automatic optimization calculation unit is constructed, and the parameter automatic optimization calculation unit is respectively connected to the image storage system (such as a PACS server) of a hospital or clinic and a radiotherapy system; Step 2, DICOM data acquisition. First, data scraping is performed. The parameter automatic optimization calculation unit automatically extracts the patient's DICOM files through the image storage system. The parameter automatic optimization calculation unit supports batch import of image data. Then, the automatic optimization calculation unit automatically parses the DICOM files, and the automatic optimization calculation unit parses the image data and the metadata related to the image data in the DICOM files. After confirming that all data is accurately read, the DICOM data acquisition is completed; Step 3, structure delineation selection. The parameter automatic optimization calculation unit automatically delineates the DICOM data, selects the structures or regions to be delineated, differentiates the tumor regions, tissue organs or other associated regions, and obtains the delineated regions; Step 4, customizing the parameters for generating the intermediate hot zone. The parameter automatic optimization calculation unit selects the intermediate hot zone according to the delineated regions obtained in the third step. By default, the intermediate hot zone is the tumor region. Set the dose gradient, size, and shape parameters of the high-dose region to meet the treatment requirements of different types of tumors. Generate the parameters for generating the intermediate hot zone according to the prescription requirements and the ratio calculated by the mathematical model; Step 5, the parameter automatic optimization calculation unit imports the parameters for generating the intermediate hot zone obtained in the previous step into the radiotherapy planning system; Step 6, the radiotherapy planning system designs the plan by the method of irradiating only the volume of the intermediate hot zone, controls the dose of the surrounding normal tissues according to the designed ratio, and outputs the radiotherapy plan; and transmits the treatment plan to the treatment device for treatment.

[0015] As Figure 2 shown, Figure 2 P1 in it is the ASCART design scheme output by the present invention; P2 is the existing ASCART design scheme; Figure 2 In it, P1 is a narrow beam, which only directly irradiates the STV (hot zone) (the core of the GTV); the dose distribution is extremely uneven, and the core / boundary dose ratio is 3 to 8 times. The dose rapidly decays outside the STV. Figure 2 In it, P2 is a wide beam that directly irradiates the entire GTV; the dose distribution is relatively uniform, and the core / boundary dose ratio is 1.1 to 2 times; the dose outside the gross tumor volume (GTV) range decreases moderately.

[0016] The optimization method for the stereotactic central ablation treatment parameters of the space - segmented radiotherapy of the present invention is a new method of space - segmented radiotherapy proposed on the basis of the previous GRID and Lattice space - segmented radiotherapy. It has the advantages of simple technical implementation, can be carried out using current radiotherapy equipment without additional purchase of accessory parts, and is easy to promote; it is applicable to the treatment of the vast majority of large - volume tumors with a size greater than 5 cm; there is an obvious correlation between the clinical effect of space - segmented irradiation and the hot - zone volume. Compared with Grid and Lattice, SCART has a larger hot - zone volume, which is 30 times and 500 times respectively, as Figures 3 to 5 shown Figures 3 to 5 Regarding the different dosimetric distributions and the separately generated hot - zone volumes produced on the same case, that is Figures 3 to 5 the different dosimetric distributions produced by Grid, Lattice and SCART on the same case are shown in Table 1 specifically;

[0017] Dmax (cGy): The highest dose generated in the hot zone; MU: The counting unit of the treatment equipment, and this item is the amount of the machine required during treatment; V100% (cc): The volume of the prescription dose.

[0018] Since a larger hot - zone volume will shrink the tumor volume faster, increase the probability of the related tumor immune response, and produce a better treatment effect; the present invention obtains the ratio of the volume and diameter of the middle hot zone (STV) to the volume of the entire treatment target area through the simulation of the standard model for the technical promotion of SCART; only irradiate the middle hot zone and no longer irradiate the entire tumor volume, so that the dose drop rate is faster and the dose of the surrounding normal tissues is lower.

[0019] The design ratio of the radiotherapy plan is that the core irradiation dose is 3 to 8 times the boundary irradiation dose.

[0020] The image data includes pixel data, resolution, slice thickness, and scanning parameters; the metadata includes patient information and examination date.

[0021] The process of generating the middle hot - zone generation parameters according to the prescription requirements and the calculation ratio of the mathematical model is as follows: 1. The parameter automatic optimization calculation unit obtains the known definitions and initial conditions: 1.1 Input data: GTVslices ∈ Rn×3, containing the coordinates of points (x1, y1, z1); 1.2 Output data: SCARTslices ∈ Rn×3, new coordinate points (x2, y2, z1); Among them, the prescription requirements are shown in Table 2 below:

[0022] 1.3 Parameters: ogapFeet: offset parameter; oshrinkpercentage: shrinkage ratio; Main loop: iterate over the range k ∈ [1 + gapFeet, j + gapFeet]; 2. Then perform initial point transformation and calculate the centroid: 2.1 Extract the point set of the middle hot zone - slice: GTVslices = {(x1, y1, z1)}; 2.2 Calculate the centroid of the polygon: (Xorigin, Yorigin) = centroid(polyshape(x1, y1)); 2.3 Translate the point coordinates to the centroid: xshift = x1 - Xorigin, yshift = y1 - Yorigin; 3. Convert to polar coordinates and optimize the centroid: 3.1 Convert to polar coordinates: (θ, ρ) = cart2pol(xshift, yshift); 3.2 Loop 360 times to adjust the centroid: First, find the current minimum and maximum radius directions: ρmin = min(ρ), θmin = θ(index(ρmin)); θmax = θmin + π, ρmax = ρ(index(min(θ - θmax))); Second, adjust the centroid according to the ρ gap: Δρ = 0.01 · (ρmax - (ρmax + ρmin) / 2); New centroid position: (Xorigin, Yorigin) ← (Xorigin, Yorigin) + pol2cart(θmax, Δρ); Then, update xshift, yshift, θ, ρ; 4. Clip the radius: Limit the radius ρ of all points: ρ(t) = {0, if ρ(t) ≤ 20 mm, ρ(t), otherwise}; 5. Scale the radius: Scale ρ ← ρ shrinkpercentage; 6. Convert back to Cartesian coordinates: Convert the polar coordinates obtained in the previous step to Cartesian coordinates: (x2, y2) = pol2cart(θ, ρ); 7. Translate back to the original centroid position: x2 ← x2 + Xorigin, y2 ← y2 + Yorigin; 8. Construct the output slices: SCARTslices = {(x2, y2, z1)}; 9. Store the result: SCARTk-gapFeet,1 = SCARTslices.

[0023] For the optimization method of the stereotactic central ablation treatment parameters in spatially fractionated radiotherapy of the present invention, during operation, first obtain the medical DICOM images, import them into the radiotherapy system, and have the doctor determine the irradiation range according to the patient's clinical data and multi-modal images; the parameter automatic optimization calculation unit can receive the contoured structures, and the parameter automatic optimization calculation unit automatically identifies the contoured structures; generate the STV according to the prescribed dose; import the automatically generated STV into the radiotherapy system; and through the optimization algorithm of the radiotherapy system, calculate the dose of the STV and evaluate it using clinical parameters; after meeting the clinical requirements, transfer it to the treatment device for treatment; the optimization method of the stereotactic central ablation treatment parameters in spatially fractionated radiotherapy of the present invention simplifies the clinical implementation of the previous two spatially fractionated irradiation methods, increases the volume of the hot zone dose (the treatment effect is related to the size of the hot zone volume), determines the standard data of the hot zone volume, and forms a standard design system.

[0024] The above embodiments are only the preferred embodiments of the present invention. Therefore, any equivalent changes or modifications made according to the structures, features, and principles described in the scope of the present invention application are included in the scope of the present invention application.

Claims

1. A method for optimizing parameters of stereotactic central ablation therapy for spatially fractionated radiotherapy, characterized in that: The method is specifically as follows: The first step is to construct a parameter automatic optimization calculation unit, which is connected to the image storage system and radiotherapy system of the hospital or clinic respectively; The second step is DICOM data acquisition. First, data is captured. The parameter automatic optimization calculation unit automatically extracts the patient's DICOM file through the image storage system. The parameter automatic optimization calculation unit supports batch import of image data. Then, the automatic optimization calculation unit automatically parses the DICOM file. The automatic optimization calculation unit parses the image data and image data-related metadata in the DICOM file. After confirming that all data are accurately read, DICOM data acquisition is completed. The third step is to select the outline structure, which automatically outlines the DICOM data through the parameter automatic optimization calculation unit, selects the structure or area to be outlined, including the tumor area, tissue organ or other related areas, and obtains the outline area; The fourth step is to customize the generation parameters of the intermediate hot zone. The parameter automatic optimization calculation unit selects the intermediate hot zone according to the outlined area obtained in the third step. The intermediate hot zone is the tumor area by default. The dose gradient, size, and shape parameters of the high-dose area are set to meet the treatment needs of different types of tumors. The generation parameters of the intermediate hot zone are generated according to the prescription requirements and the ratio calculated by the mathematical model. Step 5: The parameter automatic optimization calculation unit imports the intermediate hot zone generation parameters obtained in the previous step into the radiotherapy planning system; Step 6: The radiotherapy planning system designs the plan by irradiating only the volume of the middle hot zone, controls the dose of the surrounding normal tissues according to the designed ratio, and outputs the radiotherapy plan; And transmit the treatment plan to the treatment equipment for treatment.

2. The method for optimizing parameters of stereotactic central ablation therapy for spatially fractionated radiotherapy according to claim 1, characterized in that: The design ratio of the radiotherapy plan is that the core irradiation dose is 3 to 8 times the boundary irradiation dose.

3. The method for optimizing parameters of stereotactic central ablation therapy for spatial fractionation radiotherapy according to claim 1, characterized in that: The image data includes pixel data, resolution, inter-slice spacing, and scanning parameters; the metadata includes patient information and examination date.

4. The method for optimizing parameters of stereotactic central ablation therapy for spatial fractionation radiotherapy according to claim 1, characterized in that: The process of generating the intermediate hot zone generation parameters according to the prescription requirements and the ratio calculated by the mathematical model is as follows: First, the parameter automatic optimization calculation unit obtains known definitions and initial conditions; the details are as follows: 1.1 Input data: GTVslices∈Rn×3, containing the coordinates of the point (x1, y1, z1); 1.2 Output data: SCARTslices∈Rn×3, new coordinate point (x2, y2, z1); 1.3 Parameters: ogapFeet: offset parameter; oshrinkpercentage: reduction ratio; main loop: traversal range k∈ [1+gapFeet,j+gapFeet]; Second, the initial point transformation and centroid calculation are then performed: the point set of the middle hot zone-slice is extracted, the centroid of the polygon is calculated, and the point coordinates are translated to the centroid; Third, transform to polar coordinates and optimize the centroid; Fourth, shear radius: limit the radius ρ of all points; Fifth, scaling radius; Sixth, convert back to Cartesian coordinates: convert the polar coordinates obtained in the previous step to Cartesian coordinates; Seventh, translate back to the original center of mass position; Eighth, construct output slices; Ninth, store the results.

5. The method for optimizing parameters of stereotactic central ablation therapy for spatially fractionated radiotherapy according to claim 4, characterized in that: The process of converting to polar coordinates and optimizing the center of mass is as follows: first convert to polar coordinates (θ, ρ), and adjust the center of mass 360 times. The center of mass is adjusted as follows: first, find the minimum and maximum directions of the current radius; second, adjust the center of mass according to the ρ difference; then, update and optimize the center of mass.

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