A method and system for verifying MRI-guided adaptive radiotherapy dose

Abstract

The present application belongs to the technical field of radiotherapy dose verification, and discloses a method and system for verifying MRI-guided adaptive radiotherapy dose. By collecting MRI images of the patient during the current treatment, the tumor target area and normal tissue are delineated on the MRI image; the MRI image is converted into a pseudo-CT image, and the expected dose distribution is calculated; a three-dimensional model corresponding to the MRI image is constructed by modeling software, and the three-dimensional model is printed into a simulation phantom; at least one dose verification point for placing a first dose measurement device and an orthogonal gap for placing a second dose measurement device are determined in the tumor target area of ​​the simulation phantom; an online adaptive plan is performed on the simulation phantom through a magnetic resonance accelerator, and the actual dose distribution received by the first dose measurement device and the second dose device is collected; the actual dose distribution is compared with the expected dose distribution obtained based on the pseudo-CT image, and the accuracy of the dose calculated based on the pseudo-CT is verified according to the comparison result. The accuracy of the pseudo-CT based on MRI image conversion can be verified.

Description

Technical Field

[0001] The present application relates to the technical field of radiotherapy dose verification, and in particular to a method and system for verifying MRI-guided adaptive radiotherapy dose. Background Art

[0002] Radiotherapy is one of the main means of cancer treatment. It mainly uses X-rays to kill tumor cells, increasing the tumor dose while reducing the radiation dose to organs at risk and normal tissues. With the development of electronic computer technology and radiotherapy equipment, radiotherapy has entered the era of precision radiotherapy. For example, the current clinical routine uses intensity modulated radiotherapy (IMRT) technology, which can maximize the tumor dose while protecting normal tissues, making the radiation dose distribution more dependent on the patient's target area and the geometry of organs at risk. However, during the treatment process, due to changes in the patient's body shape, tumor changes, relative movement of organs in the body, etc., the actual radiation dose of the target area will deviate from the plan, thereby affecting the treatment effect. To solve the above problems, image-guided adaptive radiotherapy came into being.

[0003] In recent years, online adaptive radiotherapy guided by magnetic resonance imaging (MRI) has gradually entered clinical application and has become one of the most advanced image-guided radiotherapy technologies. MRI-guided online adaptive radiotherapy (MRIgART) is based on MRI images during the treatment process, real-time monitoring of changes in tumors and surrounding tissues, real-time adjustment and optimization of radiotherapy plans, and correction of deformation errors during treatment. It is a revolutionary progress and development in the development of radiotherapy technology. However, since MRI images do not have electron density information, MRI images need to be converted into pseudo-CT for dose calculation, and the accuracy of pseudo-CT directly affects the treatment results. Conventional dose verification mainly simulates beam output by various general phantoms before patient treatment to verify whether there are errors in the machine beam output, that is, whether the equipment can accurately output the expected dose according to the preset parameters and conditions, but it cannot verify whether the converted pseudo-CT is accurate. Summary of the invention

[0004] To this end, the embodiments of the present application provide a method and system for verifying MRI-guided adaptive radiotherapy dose, which can verify the accuracy of pseudo-CT based on MRI image conversion.

[0005] In a first aspect, the present application provides a method for verifying MRI-guided adaptive radiotherapy dose.

[0006] This application is achieved through the following technical solutions:

[0007] Acquiring an MRI image of the patient during the current treatment, delineating the tumor target area and normal tissue on the MRI image, and obtaining a delineation result;

[0008] converting the MRI image into a pseudo CT image, and calculating a desired dose distribution based on the pseudo CT image;

[0009] Using the delineation results to construct a three-dimensional model corresponding to the MRI image through modeling software, and printing the three-dimensional model into a simulation phantom;

[0010] Determine a dose verification point and an orthogonal gap in the tumor target area of ​​the simulation phantom; wherein a first dose measurement device is placed at the dose verification point, and a second dose measurement device is placed in the orthogonal gap;

[0011] Executing an online adaptive plan on the simulation phantom through a magnetic resonance accelerator to collect actual dose distribution received by the first dose measurement device and the second dose device;

[0012] The actual dose distribution is compared with the expected dose distribution obtained based on the pseudo CT image, and the accuracy of the dose calculated based on the pseudo CT is verified according to the comparison result.

[0013] In a preferred example of the present application, it can be further configured that the MRI image is converted into a pseudo CT image based on the electron density assignment method.

[0014] In a preferred example of the present application, it can be further configured that the step of calculating the expected dose distribution based on the pseudo CT image includes:

[0015] Setting the dose distribution parameters of radiotherapy according to the treatment goal, wherein the dose distribution parameters include the total dose of radiotherapy, the dose per fraction, the dose rate and the irradiation angle;

[0016] Based on the pseudo CT image and the dose distribution parameters, a dose calculation model is used to calculate expected dose distribution.

[0017] In a preferred example of the present application, it can be further configured that the dose calculation model adopts a Monte Carlo simulation method.

[0018] In a preferred example of the present application, it can be further configured that the first dose measurement device is a point dose measurement device, and the second dose measurement device is a surface dose measurement device.

[0019] In a second aspect, the present application provides a system for verifying MRI-guided adaptive radiotherapy dose.

[0020] This application is achieved through the following technical solutions:

[0021] A system for validating MRI-guided adaptive radiotherapy dosing.

[0022] The system comprises:

[0023] A data acquisition module is configured to acquire an MRI image of the patient during the current treatment, delineate the tumor target area and normal tissue on the MRI image, and obtain a delineation result;

[0024] an expected dose calculation module, configured to convert the MRI image into a pseudo CT image, and calculate an expected dose distribution based on the pseudo CT image;

[0025] A simulation phantom module is configured to use the delineation result to construct a three-dimensional model corresponding to the MRI image through a modeling software, and print the three-dimensional model into a simulation phantom;

[0026] Dose measurement equipment is placed in the dose verification points and orthogonal gaps of the simulation phantom to collect actual dose distribution received during the implementation of the online adaptive planning process;

[0027] The verification module is configured to compare the actual dose distribution with the expected dose distribution obtained based on the pseudo CT image, and verify the accuracy of the dose calculated based on the pseudo CT according to the comparison result.

[0028] In a preferred example of the present application, it can be further configured that the expected dose calculation module is also used to convert the MRI image into a pseudo CT image based on the electron density assignment method.

[0029] In a preferred example of the present application, it can be further configured that the expected dose calculation module is also used to set the dose distribution parameters of radiotherapy according to the treatment goal, and the dose distribution parameters include the total dose of radiotherapy, the dose of each fraction, the dose rate and the irradiation angle;

[0030] The pseudo CT image and the dose distribution parameters are input into a dose calculation model to obtain a desired dose distribution.

[0031] In a third aspect, the present application provides a device for verifying MRI-guided adaptive radiotherapy dose.

[0032] This application is achieved through the following technical solutions:

[0033] A device for verifying MRI-guided adaptive radiotherapy dose comprises a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to perform the steps of the method described in the first aspect.

[0034] In a fourth aspect, the present application provides a computer-readable storage medium.

[0035] This application is achieved through the following technical solutions:

[0036] The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method described in the first aspect are implemented.

[0037] In summary, compared with the prior art, the technical solution provided in the embodiment of the present application has at least the following beneficial effects:

[0038] Collect the MRI images of the patient during the treatment, delineate the tumor target area and normal tissue on the MRI images, and obtain the delineation results; convert the MRI images into pseudo-CT images, and calculate the expected dose distribution based on the pseudo-CT images; use the delineation results to build a three-dimensional model corresponding to the MRI image through modeling software, and print the three-dimensional model into a simulation phantom; determine a dose verification point and an orthogonal gap in the tumor target area of ​​the simulation phantom; wherein, place a first dose measurement device at the dose verification point, and place a second dose measurement device in the orthogonal gap; perform an online adaptive plan on the simulation phantom through a magnetic resonance accelerator, and collect the actual dose distribution received by the first dose measurement device and the second dose device; compare the actual dose distribution with the expected dose distribution obtained based on the pseudo-CT image, and verify the accuracy of the dose calculated based on the pseudo-CT according to the comparison results. The accuracy of the dose converted from the MRI image to the pseudo-CT can be verified, thereby ensuring the precise implementation of MRI-guided adaptive radiotherapy to the greatest extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A flowchart of a method for verifying MRI-guided adaptive radiotherapy dose provided by an exemplary embodiment of the present application;

[0040] Figure 2 A schematic diagram of the structure of a system for verifying MRI-guided adaptive radiotherapy dose provided as an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0041] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0043] In addition, the term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application, unless otherwise specified, generally indicates that the associated objects before and after are in an "or" relationship.

[0044] In this application, the terms "first", "second", etc. are used to distinguish identical or similar items with basically the same effects and functions. It should be understood that there is no logical or temporal dependency between "first", "second", and "nth", nor is there any limitation on quantity and execution order.

[0045] The embodiments of the present application are further described in detail below in conjunction with the drawings in the specification.

[0046] In one embodiment of the present application, a method for verifying MRI-guided adaptive radiotherapy dose is provided, such as Figure 1 As shown, the main steps are described as follows:

[0047] S10: Collect MRI image data of the patient during the current treatment, delineate the tumor target area and normal tissue on the MRI image, and obtain the delineation result.

[0048] Specifically, when the patient receives treatment, the patient is placed on the magnetic resonance accelerator in a stable position, and the MRI scanning parameters, such as the scanning area, scanning resolution, scanning time, etc., are set according to the treatment plan and the specific conditions of the patient to ensure that MRI image data containing sufficient image information and high quality are obtained. MRI image data includes T1-weighted images, T2-weighted images, etc. MRI image data can provide the patient's tumor location, morphology, and anatomical structure information of the tumor and surrounding tissues. In some embodiments, in order to further improve the quality of MRI image data, the image can also be pre-processed by eliminating noise, enhancing contrast, etc.

[0049] Furthermore, radiologists or radiotherapy professionals will transmit the pseudo-MRI images to the radiotherapy planning system (TPS), and outline the tumor target area (GTV, Gross Tumor Volume) according to the tumor location presented in the image. It is also necessary to outline the normal tissues or organs around the tumor target area, such as the spinal cord, brain stem, eyeball, lung, heart, liver, kidney, etc. The purpose of outlining normal tissues is to limit the irradiation dose during subsequent radiotherapy and protect normal tissues from unnecessary radiation damage. In addition, the planned target area needs to be outlined. According to the above-mentioned regional divisions, the final outline results are obtained. The outline results help to accurately determine the treatment area, protect normal tissues, formulate personalized treatment plans, and evaluate the treatment effect.

[0050] S20: Convert the MRI image data into a pseudo CT image, and calculate the expected dose distribution based on the pseudo CT image.

[0051] In some embodiments, the MRI image is converted into a pseudo CT image based on an electron density assignment method. Specifically, the electron density can be assigned according to different tissue structure types in the MRI image according to the CT average electron density value or the value recommended by ICRU (International Commission on Radiation Units and Measurements) Report No. 46 to generate a pseudo CT image.

[0052] The method of obtaining the expected dose distribution based on the pseudo CT image specifically includes: setting the dose distribution parameters of radiotherapy according to the treatment goal, the dose distribution parameters include the total dose of radiotherapy, the dose per fraction, the dose rate and the irradiation angle; and calculating the expected dose distribution using the dose calculation model based on the pseudo CT image and the dose distribution parameters. The dose calculation model adopts the Monte Carlo simulation method. The Monte Carlo simulation method can be implemented on the Talemu simulation software.

[0053] It should be noted that in order to achieve better treatment goals, the dose distribution parameters of radiotherapy need to be set according to the treatment goals, including but not limited to the total radiotherapy dose, fractionated dose, dose rate and irradiation angle. Among them, the total radiotherapy dose refers to the total radiotherapy dose that the patient needs to receive during the entire radiotherapy process, which needs to be determined based on factors such as the patient's condition, lesion site and radiosensitivity. The total radiotherapy dose needs to be sufficient to kill or inhibit tumor cells, while avoiding excessive damage to normal tissues. Fractionated dose refers to the total dose divided into multiple irradiations, and the dose of each irradiation is called the fractionated dose. The purpose of fractionated irradiation is to reduce the damage to normal tissues by single high-dose irradiation, while giving tumor cells more opportunities to be fatally damaged. Dose rate refers to the dose received per unit time, expressed in Gy / h or rad / h. Generally, the larger the dose rate, the more significant the radiation effect, and the appropriate dose rate needs to be selected according to the specific situation. The irradiation angle refers to the angle between the ray and the patient's body during radiotherapy. The selection of the irradiation angle needs to consider factors such as the location and shape of the tumor and the structure of the surrounding tissues. Selecting a suitable angle ensures that the camera can accurately irradiate the lesion site while reducing damage to the surrounding normal tissues. The radiotherapy planning system uses an optimization algorithm to calculate the position, size and shape of each irradiation field or source, as well as the dose weight of each irradiation field or source according to the dose distribution parameters. These parameters are calculated and optimized to ultimately obtain a desired dose distribution, which can cover the tumor target area to the greatest extent while minimizing the impact on surrounding normal tissues. It should be noted that the dose distribution reflects the dose distribution of the radiation at different parts or depths in the patient's body.

[0054] S30: Using the delineation results, a three-dimensional model corresponding to the MRI image data is constructed through modeling software, and the three-dimensional model is printed into a simulation model.

[0055] Specifically, the modeling software can be 3D MAX, Maya, ZBrush, etc., all of which support the import of DICOM format. The DICOM of MRI can be imported into the modeling software, and combined with the delineation results of the tumor target area and normal tissue, the corresponding three-dimensional models of different structures can be generated. After surface smoothing, noise removal, and size adjustment, the three-dimensional model can be saved in a suitable format and exported, and printed into a simulation model using 3D printing technology. Generating a personalized three-dimensional model based on the patient's MRI image data can accurately reflect the patient's anatomical structure and tissue characteristics, which is convenient for more accurate evaluation of the irradiation dose in the future.

[0056] S40: Determine at least one dose verification point and an orthogonal gap in the tumor target area of ​​the simulation phantom; wherein, a first dose measurement device is placed at the dose verification point, and a second dose measurement device is placed in the orthogonal gap.

[0057] The first dose measurement device is a point dose measurement device, and the second dose measurement device is a surface dose measurement device. Specifically, the point dose measurement device is an ionization chamber, and the ionization chamber can be selected from one of an air ionization chamber, a liquid ionization chamber, and a solid ionization chamber. The surface dose measurement device is a measuring film.

[0058] Select at least one dose verification point in the tumor target area to verify the accuracy of the dose at important locations. Select multiple dose verification points in the target tissue and important organs at risk. Comprehensively considering the verification results of multiple dose verification points can ensure more accurate verification and improve the accuracy of verification. Select a dose verification point at the center of the target tissue, and set an orthogonal gap at the dose verification point by adjusting the angle and position of the irradiation field. An orthogonal gap refers to a blank area set on two orthogonal planes (cross section or longitudinal section) to verify the accuracy of the surface dose.

[0059] S50: Execute an online adaptive plan on the simulation phantom through the magnetic resonance accelerator to collect the actual dose distribution received by the first dose measurement device and the second dose device.

[0060] Specifically, the magnetic resonance accelerator is started, the simulation phantom is placed on the treatment bed of the magnetic resonance accelerator, and an online adaptive plan is carried out. The first dose measurement device and the second dose device placed in the simulation phantom are used to collect the actual dose received, and the first actual dose collected by the first dose device and the second actual dose collected by the second dose device are comprehensively considered to determine the final actual dose distribution.

[0061] S60: Compare the actual dose distribution with the expected dose distribution obtained based on the pseudo CT image, and verify the accuracy of the dose calculated based on the pseudo CT according to the comparison result.

[0062] The actual dose distribution received by the dose measurement device during the actual treatment process is spatially matched and aligned with the expected dose distribution obtained through the pseudo-CT image to compare the dose deviation between the actual dose distribution and the expected dose distribution. In order to more intuitively judge the difference between the two, a dose deviation graph can be used to display it. The dose deviation graph contains the point-to-point difference between the actual dose distribution and the expected dose distribution, and the average value, maximum value, minimum value, and standard deviation of the dose difference can be further calculated. If the dose difference is within the acceptable preset difference range, it is considered accurate; if the dose difference exceeds the acceptable preset difference range, it is considered inaccurate.

[0063] In another embodiment of the present application, a system for verifying MRI-guided adaptive radiotherapy dose is provided, such as Figure 2As shown, the system includes: a data acquisition module 01, an expected dose calculation module 02, a simulation phantom module 03, a dose measurement device 04, and a verification module 05.

[0064] Among them, the data acquisition module 01 is configured to acquire the MRI image of the patient during the current treatment, delineate the tumor target area and normal tissue on the MRI image, and obtain the delineation result; the expected dose calculation module 02 is configured to convert the MRI image into a pseudo-CT image, and calculate the expected dose distribution based on the pseudo-CT image; the simulation phantom module 03 is configured to use the delineation result to construct a three-dimensional model corresponding to the MRI image through modeling software, and print the three-dimensional model into a simulation phantom; the dose measurement device 04 is placed in at least one dose verification point and orthogonal gap of the simulation phantom, and is used to collect the actual dose distribution received during the implementation of the online adaptive plan; the verification module 05 is configured to compare the actual dose distribution with the expected dose distribution obtained based on the pseudo-CT image, and verify the accuracy of the dose calculated based on the pseudo-CT according to the comparison result.

[0065] The expected dose calculation module 02 is also used to convert the MRI image into a pseudo CT image based on the electron density assignment method. Further, it is also used to set the dose distribution parameters of radiotherapy according to the treatment goal, and the dose distribution parameters include the total dose of radiotherapy, the dose of each dose, the dose rate and the irradiation angle; the pseudo CT image and the dose distribution parameters are input into the dose calculation model to obtain the expected dose distribution.

[0066] In one embodiment, a device for verifying MRI-guided adaptive radiotherapy dose is provided, and the device may be a server.

[0067] The device includes a processor, a memory, a network interface and a database connected through a system bus. The processor of the device is used to provide computing and control capabilities. The memory of the device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium has an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, the above-mentioned method for verifying MRI-guided adaptive radiotherapy dose is implemented.

[0068] In one embodiment, a computer-readable storage medium is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement any one of the above-mentioned methods for verifying MRI-guided adaptive radiotherapy dose.

[0069] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in the present application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink), DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0070] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device described in the present application is divided into different functional units or modules to complete all or part of the functions described above.

Claims

1. A method for verifying MRI-guided adaptive radiotherapy dose, characterized in that: The method comprises: Acquiring an MRI image of the patient during the current treatment, delineating the tumor target area and normal tissue on the MRI image, and obtaining a delineation result; Converting the MRI image into a pseudo CT image based on an electron density assignment method, and calculating a desired dose distribution based on the pseudo CT image; Using the delineation results to construct a three-dimensional model corresponding to the MRI image through modeling software, and printing the three-dimensional model into a simulation phantom; Determine at least one dose verification point and an orthogonal gap in the tumor target area of ​​the simulation phantom; wherein a first dose measurement device is placed at the dose verification point, and a second dose measurement device is placed in the orthogonal gap; Executing an online adaptive plan on the simulation phantom through a magnetic resonance accelerator to collect actual dose distribution received by the first dose measurement device and the second dose device; Comparing the actual dose distribution with the expected dose distribution obtained based on the pseudo CT image, and verifying the accuracy of the dose calculated based on the pseudo CT according to the comparison result; Wherein, calculating the expected dose distribution based on the pseudo CT image includes: Setting the dose distribution parameters of radiotherapy according to the treatment goal, wherein the dose distribution parameters include the total dose of radiotherapy, the dose per fraction, the dose rate and the irradiation angle; Based on the pseudo CT image and the dose distribution parameters, a dose calculation model is used to calculate expected dose distribution.

2. The method for verifying MRI-guided adaptive radiotherapy dose according to claim 1, characterized in that: The dose calculation model adopts the Monte Carlo simulation method.

3. The method for verifying MRI-guided adaptive radiotherapy dose according to claim 1, characterized in that: The first dose measurement device is a point dose measurement device, and the second dose measurement device is a surface dose measurement device.

4. A system for verifying MRI-guided adaptive radiotherapy dose, characterized in that: The system comprises: A data acquisition module is configured to acquire an MRI image of the patient during the current treatment, delineate the tumor target area and normal tissue on the MRI image, and obtain a delineation result; an expected dose calculation module, configured to convert the MRI image into a pseudo CT image based on an electron density assignment method, and calculate an expected dose distribution based on the pseudo CT image; wherein the module is configured to set the dose distribution parameters of radiotherapy according to the treatment goal, and the dose distribution parameters include the total dose of radiotherapy, the dose of each fraction, the dose rate, and the irradiation angle; and input the pseudo CT image and the dose distribution parameters into a dose calculation model to obtain an expected dose distribution; A simulation phantom module is configured to use the delineation result to construct a three-dimensional model corresponding to the MRI image through a modeling software, and print the three-dimensional model into a simulation phantom; a dose measurement device, placed in at least one dose verification point and an orthogonal gap of the phantom, for collecting actual dose distribution received during the implementation of the online adaptive planning process; The verification module is configured to compare the actual dose distribution with the expected dose distribution obtained based on the pseudo CT image, and verify the accuracy of the dose calculated based on the pseudo CT according to the comparison result.

5. A device for verifying MRI-guided adaptive radiotherapy dose, characterized in that: The invention comprises a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method according to any one of claims 1 to 3.

6. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 3 are implemented.

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