Beam outgoing parameter adjusting device and method of radiotherapy equipment and radiotherapy equipment

Abstract

The embodiment of the invention discloses a beam outgoing parameter adjusting device and method of radiotherapy equipment and the radiotherapy equipment. The device comprises: an outgoing beam parameter acquisition module for acquiring a CT image of a target tissue and an outgoing beam parameter of radiotherapy equipment; the initial radiation dose acquisition module is used for acquiring radiation dose distribution on the CT image; the CBCT image acquisition module is used for acquiring one or more CBCT images of the target tissue; the middle radiation dose acquisition module is used for acquiring radiation dose distribution on each CBCT image, and for each CBCT image, the radiation dose distribution on the CBCT image is calculated according to the CBCT image and the beam outgoing parameters; and the beam outgoing parameter adjustment decision module is used for comparing the radiation dose distribution on the one or more CBCT images with the radiation dose distribution on the CT image so as to determine whether the beam outgoing parameters need to be changed or not. According to the embodiment of the invention, automatic adjustment of the beam outgoing parameters of the radiotherapy equipment is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of medical imaging, in particular to a device and method for adjusting beam parameters of radiotherapy equipment and radiotherapy equipment. Background Art

[0002] Currently, CT (Computed Tomography) and CBCT (Cone Beam Computed Tomography, Cone Beam CT) imaging are widely used to guide radiotherapy (abbreviated as radiotherapy) of lesions. Specifically, after the doctor preliminarily determines the location of the lesion through diagnosis, he or she first performs CT imaging of the lesion. The doctor then locates the lesion and the important protective organs around the lesion based on the CT image. The doctor then preliminarily determines the number of radiotherapy sessions, the total radiation dose to the target area, and the maximum radiation dose of a single voxel point of the important protective organs or the upper limit of the total radiation dose within a certain volume. After that, the physicist determines the beam parameters of the radiotherapy equipment based on the location and structure of the target area and the important protective organs, and calculates the radiation dose distribution of the target area in each radiotherapy session (i.e., the radiation dose of each voxel point on the target area) based on the total radiation dose preliminarily determined by the doctor and the structure of the target area. Afterwards, after the radiotherapy process begins, before each radiotherapy session, a more accurate CBCT imaging of the lesion will be performed. The doctor will then compare the CBCT image and the CT image with the naked eye to observe whether the location and size of the lesion have changed, and decide based on experience whether the beam parameters and radiation dose need to be adjusted.

[0003] It can be seen that doctors compare CBCT images and CT images with the naked eye and decide whether to adjust the beam parameters and radiation dose based on experience. This not only increases the doctor's workload, but also, due to different doctors' experience, the changed beam parameters and radiation dose may not fully adapt to the changes in the lesions. Summary of the Invention

[0004] In view of this, on the one hand, an embodiment of the present invention proposes a device and method for adjusting the beam parameters of a radiotherapy device to achieve automatic adjustment of the beam parameters of the radiotherapy device; on the other hand, an embodiment of the present invention proposes a radiotherapy device to achieve automatic adjustment of the beam parameters of the radiotherapy device.

[0005] A device for adjusting beam parameters of a radiotherapy device, the device comprising:

[0006] A beam parameter acquisition module is used to acquire a computed tomography (CT) image of the target tissue and to obtain beam parameters of the radiotherapy device determined based on the location and structure of the lesion in the CT image.

[0007] an initial radiation dose acquisition module, which acquires the radiation dose distribution on the CT image, wherein the radiation dose distribution on the CT image is calculated based on the CT image and the beam output parameters;

[0008] a cone-beam computed tomography (CBCT) image acquisition module, which acquires one or more CBCT images of the target tissue, wherein the one or more CBCT images are acquired after the CT image, and different CBCT images are acquired at different times;

[0009] an intermediate radiation dose acquisition module, which acquires the radiation dose distribution on each CBCT image, wherein, for each CBCT image, the radiation dose distribution on the CBCT image is calculated based on the CBCT image and the beam output parameters;

[0010] The beam parameter adjustment decision module maps the radiation dose of each voxel point on each CBCT image to the corresponding voxel point on the CT image, and compares the mapped radiation dose distribution of each radiotherapy area of interest in the CT image with the original radiation dose distribution of each radiotherapy area of interest in the CT image to determine whether the beam parameter needs to be changed.

[0011] After acquiring one or more CBCT images of the target tissue, the CBCT image acquisition module is further configured to:

[0012] For each CBCT image, register the CBCT image with the CT image based on bone markers, and determine the position and structure of each radiotherapy region of interest on the CBCT image based on the registration result, wherein the radiotherapy region of interest includes: the lesion and each important protected organ;

[0013] Furthermore, after acquiring the radiation dose distribution on each CBCT image, the intermediate radiation dose acquisition module is further configured to:

[0014] For each CBCT image, the radiation dose distribution of each radiotherapy region of interest on the CBCT image is determined based on the radiation dose distribution on the CBCT image and the position and structure of each radiotherapy region of interest on the CBCT image.

[0015] When there is only one CBCT image, the beam parameter adjustment decision module compares the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image, including:

[0016] If the radiotherapy area of interest is a lesion, calculating, based on the mapped radiation dose distribution of the target area in the CT image, a first total volume of voxel points in the target area of the CT image having a mapped radiation dose greater than a preset first threshold value; calculating, based on the original radiation dose distribution of the target area in the CT image, a second total volume of voxel points in the target area of the CT image having an original radiation dose greater than the preset first threshold value; calculating a rate of change of the first total volume relative to the second total volume; and, if the rate of change is greater than a preset first upper limit, determining that the beam output parameters need to be changed;

[0017] If the radiotherapy area of interest is a vital protected organ, based on the mapped radiation dose distribution of the vital protected organ in the CT image, calculate the third total volume of voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than a preset second threshold; based on the original radiation dose distribution of the vital protected organ in the CT image, calculate the fourth total volume of voxel points on the vital protected organ in the CT image whose original radiation dose is greater than the preset second threshold; calculate the rate of change of the third total volume relative to the fourth total volume; and if the rate of change is greater than the preset second upper limit, determine that the beam output parameters need to be changed.

[0018] The beam parameter adjustment decision module compares the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image, and is further configured to:

[0019] If the radiotherapy region of interest is a lesion, finding a maximum value of the mapped radiation dose in the mapped radiation dose distribution of the target area of the CT image, and if the maximum value is greater than a preset third upper limit, determining that the beam delivery parameters need to be changed; or calculating coverage of voxel points in the target area of the CT image whose mapped radiation dose is greater than a preset first threshold, and if the coverage is less than a preset fourth upper limit, determining that the beam delivery parameters need to be changed;

[0020] If the radiotherapy area of interest is a vital protected organ, the maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the vital protected organ in the CT image, and if the maximum value is greater than the preset fifth upper limit, it is determined that the beam-out parameters need to be changed; alternatively, the total volume of voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than the preset second threshold is calculated, and if the total volume is greater than the preset sixth upper limit, it is determined that the beam-out parameters need to be changed.

[0021] When there are multiple CBCT images, the beam parameter adjustment decision module compares the mapped radiation dose distribution of each radiotherapy area of interest in the CT image with the original radiation dose distribution of each radiotherapy area of interest in the CT image, including:

[0022] If the radiotherapy area of interest is a lesion, for each voxel point on the target area of the CT image, an average of the mapped radiation doses of each CBCT image mapped to the voxel point of the CT image is calculated, and the average is used as the mapped radiation dose of the voxel point of the CT image. Then, based on the mapped radiation dose distribution of the target area of the CT image, a fifth total volume of voxels in the target area of the CT image having a mapped radiation dose greater than a preset first threshold is calculated; based on the original radiation dose distribution of the target area of the CT image, a sixth total volume of voxels in the target area of the CT image having an original radiation dose greater than the preset first threshold is calculated; a change rate of the fifth total volume relative to the sixth total volume is calculated; and if the change rate is greater than a preset first upper limit, it is determined that the beam output parameters need to be changed;

[0023] If the radiotherapy area of interest is a vital protected organ, for each voxel point on the vital protected organ in the CT image, the average of the mapped radiation doses of each CBCT image mapped to the voxel point in the CT image is calculated, and the average is used as the mapped radiation dose of the voxel point in the CT image. Then, based on the mapped radiation dose distribution of the vital protected organ in the CT image, the seventh total volume of the voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than a preset second threshold is calculated; based on the original radiation dose distribution of the vital protected organ in the CT image, the eighth total volume of the voxel points on the vital protected organ whose original radiation dose is greater than the preset second threshold is calculated; the rate of change of the seventh total volume relative to the eighth total volume is calculated; and if the rate of change is greater than a preset second upper limit, it is determined that the beam output parameters need to be changed.

[0024] The beam parameter adjustment decision module compares the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image, and is further configured to:

[0025] If the radiotherapy region of interest is a lesion, finding a maximum value of the mapped radiation dose in the mapped radiation dose distribution of the target area of the CT image, and if the maximum value is greater than a preset third upper limit, determining that the beam delivery parameters need to be changed; or calculating coverage of voxel points in the target area of the CT image whose mapped radiation dose is greater than a preset first threshold, and if the coverage is less than a preset fourth upper limit, determining that the beam delivery parameters need to be changed;

[0026] If the radiotherapy area of interest is a vital protected organ, the maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the vital protected organ in the CT image, and if the maximum value is greater than the preset fourth upper limit, it is determined that the beam-out parameters need to be changed; or, the total volume of voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than the preset second threshold is calculated, and if the total volume is greater than the preset sixth upper limit, it is determined that the beam-out parameters need to be changed.

[0027] After the beam-out parameter adjustment decision module determines whether the beam-out parameter needs to be changed, it is further configured to:

[0028] When it is determined that the beam emission parameters need to be changed, each voxel point on the CBCT image is mapped onto the CT image, and the changed beam emission parameters are determined based on the position and structure of the lesion on the mapped CT image; and, based on the mapped CT image and the changed beam emission parameters, a radiation dose distribution on the mapped CT image is obtained, and the radiation dose distribution on the mapped CT image is used as the radiation dose distribution currently applied to the target tissue.

[0029] A method for adjusting beam parameters of a radiotherapy device, the method comprising:

[0030] Acquire a computed tomography (CT) image of the target tissue; obtain beam parameters of a radiotherapy device determined based on the location and structure of the lesion in the CT image;

[0031] Acquiring a radiation dose distribution on a CT image, wherein the radiation dose distribution on the CT image is calculated based on the CT image and the beam output parameters;

[0032] Acquiring one or more cone-beam computed tomography (CBCT) images of the target tissue, wherein the one or more CBCT images are acquired after the CT image, and different CBCT images are acquired at different times;

[0033] Acquiring a radiation dose distribution on each CBCT image, wherein for each CBCT image, the radiation dose distribution on the CBCT image is calculated based on the CBCT image and the beam output parameters;

[0034] For each CBCT image, the radiation dose of each voxel point on the CBCT image is mapped to the corresponding voxel point of the CT image, and the mapped radiation dose distribution of each radiotherapy area of interest in the CT image is compared with the original radiation dose distribution of each radiotherapy area of interest in the CT image to determine whether the beam parameters need to be changed.

[0035] After acquiring one or more CBCT images of the target tissue and before acquiring the radiation dose distribution on each CBCT image, the method further includes:

[0036] For each CBCT image, register the CBCT image with the CT image based on bone markers, and determine the position and structure of each radiotherapy region of interest on the CBCT image based on the registration result, wherein the radiotherapy region of interest includes: the lesion and each important protected organ;

[0037] Furthermore, after acquiring the radiation dose distribution on each CBCT image and before comparing the radiation dose distribution on the one or more CBCT images with the radiation dose distribution on the CT image, the method further includes:

[0038] For each CBCT image, the radiation dose distribution of each radiotherapy region of interest on the CBCT image is determined based on the radiation dose distribution on the CBCT image and the position and structure of each radiotherapy region of interest on the CBCT image.

[0039] When there is only one CBCT image, comparing the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image includes:

[0040] If the radiotherapy area of interest is a lesion, calculating, based on the mapped radiation dose distribution of the target area in the CT image, a first total volume of voxel points in the target area of the CT image having a mapped radiation dose greater than a preset first threshold value; calculating, based on the original radiation dose distribution of the target area in the CT image, a second total volume of voxel points in the target area of the CT image having an original radiation dose greater than the preset first threshold value; calculating a rate of change of the first total volume relative to the second total volume; and, if the rate of change is greater than a preset first upper limit, determining that the beam output parameters need to be changed;

[0041] If the radiotherapy area of interest is a vital protected organ, based on the mapped radiation dose distribution of the vital protected organ in the CT image, calculate the third total volume of voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than a preset second threshold; based on the original radiation dose distribution of the vital protected organ in the CT image, calculate the fourth total volume of voxel points on the vital protected organ in the CT image whose original radiation dose is greater than the preset second threshold; calculate the rate of change of the third total volume relative to the fourth total volume; and if the rate of change is greater than the preset second upper limit, determine that the beam output parameters need to be changed.

[0042] The comparing the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image further comprises:

[0043] If the radiotherapy region of interest is a lesion, finding a maximum value of the mapped radiation dose in the mapped radiation dose distribution of the target area of the CT image, and if the maximum value is greater than a preset third upper limit, determining that the beam delivery parameters need to be changed; or calculating coverage of voxel points in the target area of the CT image whose mapped radiation dose is greater than a preset first threshold, and if the coverage is less than a preset fourth upper limit, determining that the beam delivery parameters need to be changed;

[0044] If the radiotherapy area of interest is a vital protected organ, the maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the vital protected organ in the CT image, and if the maximum value is greater than the preset fifth upper limit, it is determined that the beam-out parameters need to be changed; alternatively, the total volume of voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than the preset second threshold is calculated, and if the total volume is greater than the preset sixth upper limit, it is determined that the beam-out parameters need to be changed.

[0045] When there are multiple CBCT images, comparing the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image includes:

[0046] If the radiotherapy area of interest is a lesion, for each voxel point on the target area of the CT image, an average of the mapped radiation doses of each CBCT image mapped to the voxel point of the CT image is calculated, and the average is used as the mapped radiation dose of the voxel point of the CT image. Then, based on the mapped radiation dose distribution of the target area of the CT image, a fifth total volume of voxels in the target area of the CT image having a mapped radiation dose greater than a preset first threshold is calculated; based on the original radiation dose distribution of the target area of the CT image, a sixth total volume of voxels in the target area of the CT image having an original radiation dose greater than the preset first threshold is calculated; a change rate of the fifth total volume relative to the sixth total volume is calculated; and if the change rate is greater than a preset first upper limit, it is determined that the beam output parameters need to be changed;

[0047] If the radiotherapy area of interest is a vital protected organ, for each voxel point on the vital protected organ in the CT image, the average of the mapped radiation doses of each CBCT image mapped to the voxel point in the CT image is calculated, and the average is used as the mapped radiation dose of the voxel point in the CT image. Then, based on the mapped radiation dose distribution of the vital protected organ in the CT image, the seventh total volume of the voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than a preset second threshold is calculated; based on the original radiation dose distribution of the vital protected organ in the CT image, the eighth total volume of the voxel points on the vital protected organ whose original radiation dose is greater than the preset second threshold is calculated; the rate of change of the seventh total volume relative to the eighth total volume is calculated; and if the rate of change is greater than a preset second upper limit, it is determined that the beam output parameters need to be changed.

[0048] The comparing the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image further comprises:

[0049] If the radiotherapy region of interest is a lesion, finding a maximum value of the mapped radiation dose in the mapped radiation dose distribution of the target area of the CT image, and if the maximum value is greater than a preset third upper limit, determining that the beam delivery parameters need to be changed; or calculating coverage of voxel points in the target area of the CT image whose mapped radiation dose is greater than a preset first threshold, and if the coverage is less than a preset fourth upper limit, determining that the beam delivery parameters need to be changed;

[0050] If the radiotherapy area of interest is a vital protected organ, the maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the vital protected organ in the CT image, and if the maximum value is greater than the preset fourth upper limit, it is determined that the beam-out parameters need to be changed; or, the total volume of voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than the preset second threshold is calculated, and if the total volume is greater than the preset sixth upper limit, it is determined that the beam-out parameters need to be changed.

[0051] After determining whether the beam-emitting parameters need to be changed, the method further includes:

[0052] When it is determined that the beam emission parameters need to be changed, each voxel point on the CBCT image is mapped onto the CT image, and the changed beam emission parameters are determined based on the position and structure of the lesion on the mapped CT image; and, based on the mapped CT image and the changed beam emission parameters, a radiation dose distribution on the mapped CT image is obtained, and the radiation dose distribution on the mapped CT image is used as the radiation dose distribution currently applied to the target tissue.

[0053] A radiotherapy device, comprising the beam parameter adjustment device of any radiotherapy device described above.

[0054] In an embodiment of the present invention, a CT image of the target tissue is first automatically acquired, and beam delivery parameters of the radiotherapy device are automatically acquired based on the location and structure of the lesion in the CT image. Then, a radiation dose distribution on the CT image is calculated based on the CT image and the beam delivery parameters. Then, one or more CBCT images of the target tissue are automatically acquired. Then, a radiation dose distribution on each CBCT image is automatically acquired based on each CBCT image and the beam delivery parameters. Then, for each CBCT image, the radiation dose of each voxel point on the CBCT image is automatically mapped to the corresponding voxel point on the CT image. The mapped radiation dose distribution of each radiotherapy area of interest in the CT image is compared with the original radiation dose distribution of each radiotherapy area of interest in the CT image to determine whether the beam delivery parameters need to be changed. This eliminates the need for manual intervention and achieves fully automatic decision-making and adjustment on whether the beam delivery parameters need to be changed. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so that those skilled in the art will understand the above and other features and advantages of the present invention more clearly. In the accompanying drawings:

[0056] Figure 1 A schematic structural diagram of a beam parameter adjustment device for a radiotherapy device according to an embodiment of the present invention;

[0057] Figure 2 1 is a schematic diagram of mapping when the shape of a lesion on a CBCT image changes relative to that on a CT image in an application example;

[0058] Figure 3 FIG1 is a schematic diagram of mapping when the shape of a lesion on a CBCT image changes relative to that on a CT image in another application example;

[0059] Figure 4 This is a flow chart of a method for adjusting beam parameters of a radiotherapy device provided in one embodiment of the present invention.

[0060] The accompanying drawings are numerals as follows:

[0061]

[0062] DETAILED DESCRIPTION

[0063] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail with reference to the following examples.

[0064] Figure 1 This is a schematic diagram of the structure of a beam parameter adjustment device 10 for a radiotherapy device according to an embodiment of the present invention. Figure 1 As shown, the device 10 mainly includes: a beam parameter acquisition module 11, an initial radiation dose acquisition module 12, a CBCT image acquisition module 13, an intermediate radiation dose acquisition module 14 and a beam parameter adjustment decision module 15, wherein:

[0065] (1) The beam parameter acquisition module 11 acquires a CT image of the target tissue and obtains beam parameters of the radiotherapy device determined according to the location and structure of the lesion in the CT image.

[0066] Beam parameters are used to define the angle and range of the radiation beam emitted by the radiotherapy device, ensuring that the beam precisely covers the lesion. Acquiring a CT image of the target tissue reveals the location and structure of the lesion (i.e., the target volume). Based on this location and structure, the beam parameters of the radiotherapy device are determined.

[0067] After the radiotherapy equipment's beam parameters are determined, they are stored in a settings database. CT images are typically also stored in the same database, for example, in a radiotherapy planning platform used by physicists to develop radiotherapy plans. The beam parameter acquisition module 11 can obtain the target tissue's CT image and the radiotherapy equipment's beam parameters from this database via a DICom (Digital Imaging and Communications in Medicine) node, for example.

[0068] (2) The initial radiation dose acquisition module 12 acquires the radiation dose distribution on the CT image, wherein the radiation dose distribution on the CT image is calculated based on the CT image and the beam parameters acquired by the beam parameter acquisition module 11.

[0069] Specifically, the position and range of the target area (i.e., lesion) on the CT image can be known based on the beam parameters, so that the radiation dose distribution on the CT image can be calculated using a preset radiation dose calculation algorithm. The radiation dose distribution on the CT image refers to the radiation dose of each voxel point on the CT image, which includes not only the radiation dose of each voxel point on the target area (i.e., lesion), but also the radiation dose of each voxel point on the important protected organs around the target area. This is because: although the beam parameters limit the irradiation range of the radiation to only the lesion (i.e., target area), due to the scattering or transmission of the radiation, a small amount of radiation will also be scattered or transmitted to the organs around the lesion. The radiation dose calculation algorithm can adopt the AAA (Anisotropic Analytical Algorithm, anisotropic algorithm) or AXB (Acuros eXternal Beam, photon dose) algorithm, etc.

[0070] The radiation dose distribution on the CT image is typically calculated on the radiotherapy planning platform and stored in the platform's database. The initial radiation dose acquisition module 12 can obtain the radiation dose distribution on the CT image from the platform's database. Specifically, the beam parameter acquisition module 11 transmits the CT image identifier to the initial radiation dose acquisition module 12, which then obtains the radiation dose distribution on the CT image from the platform's database based on the CT image identifier.

[0071] (3) The CBCT image acquisition module 13 acquires one or more CBCT images of the target tissue, wherein the one or more CBCT images are acquired after the CT image, and different CBCT images are acquired at different times.

[0072] In practical applications, considering that the location and / or size of the lesion may change as the radiotherapy process progresses, a CBCT image of the target tissue is acquired before each radiotherapy session. This CBCT image can better reflect the latest status of the lesion. Here, the CBCT image acquisition module 13 acquiring one or more CBCT images of the target tissue refers to acquiring one or more recently acquired CBCT images of the target tissue, i.e., acquiring a CBCT image of the target tissue acquired during the most recent radiotherapy session, or acquiring multiple CBCT images of the target tissue acquired during the most recent radiotherapy sessions.

[0073] (4) An intermediate radiation dose acquisition module 14 is configured to acquire the radiation dose distribution on each CBCT image. For each CBCT image, the radiation dose distribution on the CBCT image is calculated based on the CBCT image and the beam parameters acquired by the beam parameter acquisition module 11 .

[0074] Here, it is assumed that the beam parameters acquired by the beam parameter acquisition module 11 are still applicable to each CBCT image. Therefore, for each CBCT image, the beam parameters acquired by the beam parameter acquisition module 11 are still used to calculate the radiation dose distribution on each CBCT image.

[0075] The radiation dose calculation algorithm used to calculate the radiation dose distribution on each CBCT image is the same as the one used to calculate the radiation dose distribution on the CT image. It should be noted that, as the location and / or structure of the lesion changes during radiotherapy, the voxel value of the same voxel on the CBCT image and the CT image may be different. Therefore, even if the same radiation dose calculation algorithm and beam parameters are used, the calculated radiation dose for the voxel on the CBCT image and the CT image may be different.

[0076] The radiation dose distribution on each CBCT image is usually calculated on the radiotherapy planning platform and stored in the database of the radiotherapy planning platform. The intermediate radiation dose acquisition module 14 can obtain the radiation dose distribution on each CBCT image from the database of the radiotherapy planning platform. CBCT images are usually stored on the multimodal image management platform. After the radiotherapy planning platform obtains one or more CBCT images from the multimodal image management platform, it calculates the radiation dose distribution on each CBCT image. Among them, the CBCT image acquisition module 13 sends the identification of one or more CBCT images to the intermediate radiation dose acquisition module 14. The intermediate radiation dose acquisition module 14 obtains the radiation dose distribution on one or more CBCT images from the database of the radiotherapy planning platform based on the identification of one or more CBCT images.

[0077] (5) The beam parameter adjustment decision module 15 maps the radiation dose of each voxel point on each CBCT image to the corresponding voxel point on the CT image, and compares the mapped radiation dose distribution of each radiotherapy area of interest in the CT image with the original radiation dose distribution of each radiotherapy area of interest in the CT image to determine whether the beam parameters need to be changed.

[0078] In practical applications, a deformable registration algorithm (also known as an elastic deformation registration algorithm) can be used to map the radiation dose of each voxel point on the CBCT image to the corresponding voxel point on the CT image. The specific steps of the deformable registration algorithm can be as follows:

[0079] The first step is rigid registration

[0080] That is, the CBCT image is translated and / or rotated to eliminate the overall displacement between the CBCT image and the CT image caused by differences in patient postures, etc.

[0081] Step 2: Elastic deformation modeling

[0082] In this step, the non-rigid displacement between voxels in the CBCT image and the CT image is calculated using algorithms such as B-splines, optical flow, or Demons. Then, by optimizing similarity metrics such as MI (mutual information) and MSE (mean square error), the anatomical structure of the CBCT image is matched pixel by pixel with the CT image to simulate tissue deformation such as organ displacement or deformation.

[0083] The third step is to generate a three-dimensional DVF (Displacement Vector Field) to quantify the displacement direction and distance of each voxel from the CT image to the CBCT image.

[0084] In the fourth step, the 3D DVF is applied to the CT image to generate a deformed radiation dose distribution on the CT image that is spatially aligned with the CBCT image. In the above embodiment, a CT image of the target tissue is first automatically acquired, and the beam delivery parameters of the radiotherapy device are automatically determined based on the location and structure of the lesion in the CT image. A radiation dose distribution on the CT image is then calculated based on the CT image and the beam delivery parameters. One or more CBCT images of the target tissue are then automatically acquired, and a radiation dose distribution on each CBCT image is automatically obtained based on each CBCT image and the beam delivery parameters. For each CBCT image, the radiation dose of each voxel in the CBCT image is automatically mapped to the corresponding voxel in the CT image. The mapped radiation dose distribution for each radiotherapy area of interest in the CT image is compared with the original radiation dose distribution for each radiotherapy area of interest in the CT image to determine whether the beam delivery parameters need to be modified. This eliminates the need for manual intervention and enables fully automated decision-making and adjustment of whether the beam delivery parameters need to be modified.

[0085] In practical applications, the beam parameter adjustment device 10 of the radiotherapy equipment provided by the embodiment of the present invention may be located on a multimodal image management platform dedicated to maintaining CBCT images.

[0086] In an optional embodiment, after acquiring one or more CBCT images of the target tissue, the CBCT image acquisition module 13 is further configured to: for each CBCT image, perform bone marker-based registration of the CBCT image with the CT image, and determine, based on the registration result, the position and structure of each radiotherapy region of interest on the CBCT image, wherein the radiotherapy region of interest includes: the lesion and each important protected organ;

[0087] Moreover, after the intermediate radiation dose acquisition module 14 acquires the radiation dose distribution on each CBCT image, it is further used to: for each CBCT image, determine the radiation dose distribution of each radiotherapy area of interest on the CBCT image based on the radiation dose distribution on the CBCT image and the position and structure of each radiotherapy area of interest on the CBCT image.

[0088] Considering that while the location and / or structure (e.g., volume) of lesions may change as the disease progresses or improves, the location and structure of bones generally remain constant, CBCT images are registered with CT images based on bony landmarks to accurately determine the location and structure of each radiotherapy region of interest (including lesions and critical organs) on the CBCT images. For critical organs, excessive radiation exposure can damage them, so the radiation dose distribution to these organs also requires attention.

[0089] Since the radiation dose distribution on the CBCT image is calculated based on the same beam output parameters as the radiation dose distribution on the CT image, that is, it is calculated based on the consistency of the position and structure of the lesion on the CT image and the CBCT image, that is, it is calculated on the premise that the position and structure of the lesion have not changed. In actual applications, the position and / or structure of the lesion is likely to change with the passage of time. In this case, the position and / or structure of the target area restricted by the beam output parameters should change accordingly. At this time, the radiation dose distribution of the lesion and the important protected organs on the CBCT image calculated based on the same beam output parameters as the CT image must be different from the radiation dose distribution of the lesion and the important protected organs on the CT image. So how to calculate this difference? The ideas given in the embodiments of the present invention are as follows:

[0090] Taking into account that: when the position and / or structure of the lesion changes, the position and / or structure of the target area corresponding to the original beam parameters do not correspond to the actual position and / or structure of the lesion on the CBCT image. Therefore, after mapping the radiation dose distribution on the CBCT image calculated based on the original beam parameters onto the CT image and then comparing it with the original radiation dose distribution on the CT image, it can be determined whether the position and / or structure of the lesion has changed, and whether the original beam parameters are still suitable for the CBCT image.

[0091] For example, when the shape of a lesion on a CBCT image changes relative to that on a CT image, resulting in the use of the original beam parameters to irradiate the lesion on the CBCT image, part of the lesion will not be within the irradiation range (i.e., not within the target area). After the actual lesion on the CBCT image is mapped to the CT image, the mapped radiation dose of some voxel points in the target area of the CT image defined by the original beam parameters will be 0. Consequently, there will be a significant difference between the mapped radiation dose distribution of the target area on the CT image and the original radiation dose distribution of the target area on the CT image.

[0092] Figure 2 2 is a schematic diagram of mapping when the shape of a lesion on a CBCT image changes relative to that on a CT image in an application example. 21 is a schematic diagram of a CT image; 22 is a schematic diagram of a CBCT image; 23 is a schematic diagram of mapping the radiation dose of each voxel point on the CBCT image 22 to the corresponding voxel point on the CT image 21.

[0093] The rectangular area 211 corresponds to the body of the patient before radiotherapy begins. The rectangular area 212 corresponds to the vital organs to be protected. The elliptical area 213 corresponds to the lesion. The elliptical area 214, which is surrounded by the dotted line, is the irradiation area with the original beam parameters, i.e., the target area.

[0094] The rectangular area 221 corresponds to the body of the patient during radiotherapy. The rectangular area 222 corresponds to the important organs to be protected during radiotherapy. The elliptical area 223 corresponds to the lesion during radiotherapy. The elliptical area 224, which is surrounded by the dotted line, is the irradiation area using the original beam parameters, i.e., the target area.

[0095] The rectangular area corresponding to 222-2 is a schematic diagram of mapping the radiation dose of each voxel point on 222 to the corresponding voxel point on 212; the size and shape of 222-2 completely match those of 212;

[0096] The elliptical area corresponding to 223-2 is a schematic diagram of mapping the radiation dose of each voxel point on 223 to the corresponding voxel point on 213; the size and shape of 223-2 completely match those of 213;

[0097] The elliptical area corresponding to 224-2 is a schematic diagram of mapping the radiation dose at each voxel point on 224 to the corresponding voxel point on 211. Ellipse 224-2 represents the area with a radiation dose distribution, while the area outside ellipse 224-2 represents the area without any radiation dose distribution. Since 223 is an oblate ellipse and 213 is an oblong ellipse, mapping 223 to 213 compresses the width of 224, resulting in the narrow, elongated shape shown in 224-2. The red area in 22 (i.e., the overlapping area of 223 and 224) is mapped to the red area in 23, the green area in 22 is mapped to the green area in 23, and the blue area in 22 is mapped to the blue area in 23.

[0098] The rectangular area corresponding to 221 - 2 is a schematic diagram of mapping 221 onto 211 ; the size and shape of 221 - 2 completely match those of 211 .

[0099] Comparing 22 and 21, it can be seen that lesion 223 on CBCT image 22 has changed shape, becoming flatter, compared to lesion 213 on CT image 21. This results in the following: when the original beam delivery parameters are used to irradiate the radiotherapy target, part of lesion 223 (i.e., the green area) is not irradiated, i.e., is located outside the target area. Therefore, the radiation dose to the lesion area outside the target area (i.e., the green area) is 0. As can be clearly seen from 224-2 in 23, there is no radiation dose distribution in the green area of lesion 223. Therefore, the original beam delivery parameters are no longer suitable for lesion 223 in CBCT image 22.

[0100] Figure 3 FIG1 is a schematic diagram of a mapping when the shape of a lesion on a CBCT image changes relative to that on a CT image in another application example.

[0101] 31 is a schematic diagram of a CT image; 32 is a schematic diagram of a CBCT image; 33 is a schematic diagram of mapping the radiation dose of each voxel point on the CBCT image 32 to the corresponding voxel point on the CT image 31;

[0102] 311 is the body of the subject before radiotherapy begins, 312 is the important protected organs, 313 is the lesion, and 314, the area surrounded by the dotted line, is the irradiation area of the original beam parameters, i.e., the target area;

[0103] Reference numeral 321 denotes the body of the subject during radiotherapy, reference numeral 322 denotes an important protected organ, reference numeral 323 denotes a lesion, and reference numeral 324, i.e., the area enclosed by the dotted line, denotes the irradiation area, i.e., the target area, using the original beam delivery parameters.

[0104] 322 - 2 is a schematic diagram of mapping the radiation dose of each voxel point on 322 to the corresponding voxel point on 312 , and the size and shape of 322 - 2 completely match those of 312 ;

[0105] 323 - 2 is a schematic diagram of mapping the radiation dose of each voxel point on 323 to the corresponding voxel point on 313 , and the size and shape of 323 - 2 completely match those of 313 ;

[0106] 324 - 2 is a schematic diagram of mapping the radiation dose of each voxel point on 324 to the corresponding voxel point on 311 , that is, the ellipse 324 - 2 is the area with radiation dose distribution, and the area outside the ellipse 324 - 2 is the area without any radiation dose distribution;

[0107] 321 - 2 is a schematic diagram of mapping 321 onto 311 , and the size and shape of 321 - 2 completely match those of 311 .

[0108] Comparing images 32 and 31 reveals that lesion 323 on CBCT image 32 has changed shape compared to lesion 313 on CT image 31, significantly reducing its size. This has caused the vital organs, previously squeezed to the left by lesion 313, to return to the right, shifting rightward. Consequently, when the original beam parameters are used to irradiate the subject, portions of the vital organs are irradiated, effectively falling within the target volume. This clearly poses a risk of harm to the vital organs. 324-2 in image 33 clearly shows that the area to the right of the vital organs also has a radiation dose distribution, potentially damaging them. Therefore, the original beam parameters are no longer suitable for the vital organs in CBCT image 32.

[0109] In an optional embodiment, when there is only one CBCT image, the beam parameter adjustment decision module 15 compares the mapped radiation dose distribution of each radiotherapy area of interest in the CT image with the original radiation dose distribution of each radiotherapy area of interest in the CT image, including: if the radiotherapy area of interest is a lesion, based on the mapped radiation dose distribution of the target area of the CT image, calculating a first total volume of voxel points on the target area of the CT image whose mapped radiation dose is greater than a preset first threshold; based on the original radiation dose distribution of the target area of the CT image, calculating a second total volume of voxel points on the target area of the CT image whose original radiation dose is greater than the preset first threshold; calculating a change rate of the first total volume relative to the second total volume; and if the change rate is greater than a preset first upper limit, determining that the beam parameter needs to be changed; wherein the specific values of the first threshold and the first upper limit can be set based on experience, etc.; wherein the original radiation dose distribution of the target area of the CT image is the radiation dose distribution on the CT image acquired by the initial radiation dose acquisition module 12; the change rate of the first total volume relative to the second total volume = (the absolute value of the difference between the first total volume and the second total volume) / the second total volume;

[0110] If the area of interest for radiotherapy is a vital protected organ, the third total volume of voxel points on the CT image whose mapped radiation dose is greater than a preset second threshold is calculated based on the mapped radiation dose distribution of the vital protected organ in the CT image; the fourth total volume of voxel points on the CT image whose original radiation dose is greater than the preset second threshold is calculated based on the original radiation dose distribution of the vital protected organ in the CT image; the rate of change of the third total volume relative to the fourth total volume is calculated; and if the rate of change is greater than the preset second upper limit, it is determined that the beam parameters need to be changed; wherein the specific values of the second threshold and the second upper limit can be set based on experience, etc.; the rate of change of the third total volume relative to the fourth total volume = (the absolute value of the difference between the third total volume and the fourth total volume) / fourth total volume.

[0111] In practical applications, when the beam parameter adjustment decision module 15 calculates: the first total volume of voxel points on the target area of the CT image whose mapped radiation dose is greater than the preset first threshold, the second total volume of voxel points on the target area of the CT image whose original radiation dose is greater than the preset first threshold, and the rate of change of the first total volume relative to the second total volume, the three parameters and their values can be displayed on the front-end interface, and when the rate of change of the first total volume relative to the second total volume is greater than the preset first upper limit, a prompt for changing the beam parameters is given on the front-end interface.

[0112] Similarly, when the beam parameter adjustment decision module 15 calculates: the third total volume of voxel points on each important protected organ in the CT image whose mapped radiation dose is greater than the preset second threshold, the fourth total volume of voxel points on the important protected organ in the CT image whose original radiation dose is greater than the preset second threshold, and the rate of change of the third total volume relative to the fourth total volume, the three parameters and their values can be displayed on the front-end interface, and when the rate of change of the third total volume relative to the fourth total volume is greater than the preset second upper limit, a prompt for changing the beam parameters is given on the front-end interface.

[0113] Among them, if the beam parameter adjustment device 10 of the radiotherapy equipment has a display screen, the above information will be displayed on the display screen; otherwise, the beam parameter adjustment decision module 15 can send the above information to the radiotherapy plan making platform with a display screen, and the radiotherapy plan making platform will display the above information on its own display screen.

[0114] In an optional embodiment, the beam parameter adjustment decision module 15 compares the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image, and is further configured to:

[0115] If the radiotherapy area of interest is a lesion, the maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the target area of the CT image. If the maximum value is greater than a preset third upper limit, it is determined that the beam parameters need to be changed. Alternatively, the coverage of voxel points in the target area of the CT image whose mapped radiation dose is greater than a preset first threshold is calculated. If the coverage is less than a preset fourth upper limit, it is determined that the beam parameters need to be changed. The specific values of the third upper limit and the fourth upper limit can be set based on experience.

[0116] If the radiotherapy area of interest is a vital protected organ, the maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the vital protected organ in the CT image, and if the maximum value is greater than the preset fifth upper limit, it is determined that the beam-out parameters need to be changed; alternatively, the total volume of voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than the preset second threshold is calculated, and if the total volume is greater than the preset sixth upper limit, it is determined that the beam-out parameters need to be changed; wherein, the specific values of the fifth upper limit and the sixth upper limit can be set based on experience.

[0117] In actual applications, when the beam parameter adjustment decision module 15 finds the maximum value of the mapped radiation dose of the target area of the CT image and calculates the coverage of voxel points on the target area of the CT image whose mapped radiation dose is greater than a preset first threshold, the two parameters and their values can be displayed on the front-end interface, and when the maximum value is greater than a preset third upper limit and when the coverage is less than a preset fourth upper limit, a prompt for changing the beam parameters is given on the front-end interface.

[0118] Similarly, when the beam parameter adjustment decision module 15 finds the maximum value of the mapped radiation dose of each important protected organ in the CT image, and when it calculates the total volume of voxel points on each important protected organ in the CT image whose mapped radiation dose is greater than the preset second threshold, the two parameters and their values can be displayed on the front-end interface, and when the maximum value is greater than the preset fifth upper limit, and when the total volume is greater than the preset sixth upper limit, a prompt for changing the beam parameters is given on the front-end interface.

[0119] In practical applications, after determining the location and structure of each radiotherapy ROI on the CBCT image, the CBCT image acquisition module 13 can further calculate the volume of each radiotherapy ROI on the latest CBCT image and send the volume of each radiotherapy ROI on the latest CBCT image to the beam parameter adjustment and decision module 15. Furthermore, the beam parameter adjustment and decision module 15 is further configured to obtain the volume of each radiotherapy ROI on the CT image and display the volume of each radiotherapy ROI on the latest CBCT image and the volume of each radiotherapy ROI on the CT image on the front-end interface. The beam parameter adjustment and decision module 15 can obtain the volume of each radiotherapy ROI on the CT image from the radiotherapy planning platform.

[0120] Among them, if the beam parameter adjustment device 10 of the radiotherapy equipment has a display screen, the above information will be displayed on the display screen; otherwise, the beam parameter adjustment decision module 15 can send the above information to the radiotherapy plan making platform with a display screen, and the radiotherapy plan making platform will display the above information on its own display screen.

[0121] In an optional embodiment, when there are multiple CBCT images, the beam parameter adjustment decision module 15 compares the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image, including:

[0122] If the radiotherapy area of interest is a lesion, for each voxel point on the target area of the CT image, the average of the mapped radiation doses of each CBCT image mapped to the voxel point of the CT image is calculated, and the average is used as the mapped radiation dose of the voxel point of the CT image. Then, based on the mapped radiation dose distribution of the target area of the CT image, the fifth total volume of the voxels in the target area of the CT image whose mapped radiation dose is greater than a preset first threshold is calculated; based on the original radiation dose distribution of the target area of the CT image, the sixth total volume of the voxels in the target area of the CT image whose original radiation dose is greater than the preset first threshold is calculated; the rate of change of the fifth total volume relative to the sixth total volume is calculated; and if the rate of change is greater than a preset first upper limit, it is determined that the beam output parameters need to be changed; the rate of change of the fifth total volume relative to the sixth total volume = (the absolute value of the difference between the fifth total volume and the sixth total volume) / the sixth total volume;

[0123] If the area of interest for radiotherapy is a critical protected organ, for each voxel point on the critical protected organ in the CT image, the average of the mapped radiation doses of each CBCT image mapped to the voxel point in the CT image is calculated, and the average is used as the mapped radiation dose of the voxel point in the CT image. Then, based on the mapped radiation dose distribution of the critical protected organ in the CT image, the seventh total volume of the voxel points on the critical protected organ in the CT image whose mapped radiation dose is greater than a preset second threshold is calculated; based on the original radiation dose distribution of the critical protected organ in the CT image, the eighth total volume of the voxel points on the critical protected organ whose mapped radiation dose is greater than the preset second threshold is calculated; the rate of change of the seventh total volume relative to the eighth total volume is calculated; and if the rate of change is greater than the preset second upper limit, it is determined that the beam parameters need to be changed; the rate of change of the seventh total volume relative to the eighth total volume = (the absolute value of the difference between the seventh total volume and the eighth total volume) / the eighth total volume.

[0124] In an optional embodiment, the beam parameter adjustment decision module 15 compares the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image, and is further configured to:

[0125] If the radiotherapy area of interest is a lesion, a maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the target area of the CT image, and if the maximum value is greater than a preset third upper limit, it is determined that the beam parameters need to be changed; alternatively, a coverage of voxel points in the target area of the CT image whose mapped radiation dose is greater than a preset first threshold is calculated, and if the coverage is less than a preset fourth upper limit, it is determined that the beam parameters need to be changed;

[0126] If the radiotherapy area of interest is a vital protected organ, the maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the vital protected organ in the CT image, and if the maximum value is greater than the preset fourth upper limit, it is determined that the beam parameters need to be changed; alternatively, the total volume of voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than the preset second threshold is calculated, and if the total volume is greater than the preset sixth upper limit, it is determined that the beam parameters need to be changed.

[0127] In an optional embodiment, after determining whether the beam parameters need to be changed, the beam parameter adjustment decision module 15 is further configured to: when it is determined that the beam parameters need to be changed, map each voxel point on the CBCT image onto the CT image, and determine the changed beam parameters based on the position and structure of the lesion on the mapped CT image; and, based on the mapped CT image and the changed beam parameters, obtain a radiation dose distribution on the mapped CT image, and use the radiation dose distribution on the mapped CT image as the radiation dose distribution currently used for the target tissue.

[0128] Figure 4 This is a flow chart of a method for adjusting the beam parameters of a radiotherapy device provided in one embodiment of the present invention. Figure 4 As shown, the specific steps are as follows:

[0129] Step 401: Acquire a CT image of the target tissue; and obtain beam parameters of a radiotherapy device determined according to the location and structure of the lesion in the CT image.

[0130] Step 402 : Acquire the radiation dose distribution on the CT image, wherein the radiation dose distribution on the CT image is calculated based on the CT image and the beam parameters acquired in step 401 .

[0131] Step 403 : Acquire one or more CBCT images of the target tissue, wherein the one or more CBCT images are acquired after the CT image of step 401 , and different CBCT images are acquired at different times.

[0132] CT images are obtained after the doctor has initially determined the location of the lesion through diagnosis. The doctor then uses the CT images to locate the lesion and the vital organs surrounding it. The doctor and physicist then develop a radiotherapy plan, which primarily includes the number of treatments, beam parameters, and the distribution of radiation dose to the target area and vital organs during each treatment. After the radiotherapy process begins and before each treatment, a more accurate CBCT scan of the lesion is performed.

[0133] Step 404 : Obtain radiation dose distribution on each CBCT image, wherein for each CBCT image, the radiation dose distribution on the CBCT image is calculated based on the CBCT image and the beam parameters obtained in step 401 .

[0134] Step 405: For each CBCT image, the radiation dose of each voxel point on the CBCT image is mapped to the corresponding voxel point on the CT image, and the mapped radiation dose distribution of each radiotherapy area of interest in the CT image is compared with the original radiation dose distribution of each radiotherapy area of interest in the CT image to determine whether the beam parameters obtained in step 401 need to be changed.

[0135] In an optional embodiment, after step 403 and before step 404, the method further includes: for each CBCT image, registering the CBCT image with the CT image based on bone markers, and determining the position and structure of each radiotherapy region of interest on the CBCT image based on the registration result, wherein the radiotherapy region of interest includes: the lesion and each important protected organ;

[0136] Furthermore, after step 404 and before step 405, the method further includes: for each CBCT image, determining the radiation dose distribution of each radiotherapy region of interest on the CBCT image according to the radiation dose distribution on the CBCT image and the position and structure of each radiotherapy region of interest on the CBCT image.

[0137] In an optional embodiment, when there is only one CBCT image, in step 405, comparing the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image includes:

[0138] If the radiotherapy area of interest is a lesion, a first total volume of voxels in the target area of the CT image having a mapped radiation dose greater than a preset first threshold is calculated based on the mapped radiation dose distribution of the target area of the CT image; a second total volume of voxels in the target area of the CT image having an original radiation dose greater than the preset first threshold is calculated based on the original radiation dose distribution of the target area of the CT image; a rate of change of the first total volume relative to the second total volume is calculated; and if the rate of change is greater than a preset first upper limit, it is determined that the beam output parameters obtained in step 401 need to be changed;

[0139] If the radiotherapy area of interest is a critical protected organ, based on the mapped radiation dose distribution of the critical protected organ in the CT image, calculate the third total volume of voxel points on the critical protected organ in the CT image whose mapped radiation dose is greater than a preset second threshold; based on the original radiation dose distribution of the critical protected organ in the CT image, calculate the fourth total volume of voxel points on the critical protected organ in the CT image whose original radiation dose is greater than the preset second threshold; calculate the rate of change of the third total volume relative to the fourth total volume; and if the rate of change is greater than the preset second upper limit, determine that the beam output parameters obtained in step 401 need to be changed.

[0140] In an optional embodiment, in step 405, comparing the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image further includes:

[0141] If the radiotherapy region of interest is a lesion, a maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the target area of the CT image. If the maximum value is greater than a preset third upper limit, it is determined that the beam delivery parameters obtained in step 401 need to be changed. Alternatively, a coverage of voxel points in the target area of the CT image having a mapped radiation dose greater than a preset first threshold is calculated. If the coverage is less than a preset fourth upper limit, it is determined that the beam delivery parameters obtained in step 401 need to be changed.

[0142] If the radiotherapy area of interest is a critical protected organ, the maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the critical protected organ in the CT image. If the maximum value is greater than the preset fifth upper limit, it is determined that the beam-out parameters obtained in step 401 need to be changed; alternatively, the total volume of voxel points on the critical protected organ in the CT image whose mapped radiation dose is greater than the preset second threshold is calculated. If the total volume is greater than the preset sixth upper limit, it is determined that the beam-out parameters obtained in step 401 need to be changed.

[0143] In an optional embodiment, when there are multiple CBCT images, in step 405, comparing the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image includes:

[0144] If the radiotherapy area of interest is a lesion, for each voxel point on the target area of the CT image, the average of the mapped radiation doses of each CBCT image mapped to the voxel point of the CT image is calculated, and the average is used as the mapped radiation dose of the voxel point of the CT image. Then, based on the mapped radiation dose distribution of the target area of the CT image, a fifth total volume of voxels in the target area of the CT image having a mapped radiation dose greater than a preset first threshold is calculated; based on the original radiation dose distribution of the target area of the CT image, a sixth total volume of voxels in the target area of the CT image having an original radiation dose greater than the preset first threshold is calculated; the rate of change of the fifth total volume relative to the sixth total volume is calculated; and if the rate of change is greater than a preset first upper limit, it is determined that the beam output parameters obtained in step 401 need to be changed;

[0145] If the radiotherapy area of interest is a critical protected organ, for each voxel point on the critical protected organ in the CT image, the average of the mapped radiation doses of each CBCT image mapped to the voxel point in the CT image is calculated, and the average is used as the mapped radiation dose of the voxel point in the CT image. Then, based on the mapped radiation dose distribution of the critical protected organ in the CT image, the seventh total volume of the voxel points on the critical protected organ in the CT image whose mapped radiation dose is greater than a preset second threshold is calculated; based on the original radiation dose distribution of the critical protected organ in the CT image, the eighth total volume of the voxel points on the critical protected organ whose original radiation dose is greater than the preset second threshold is calculated; the rate of change of the seventh total volume relative to the eighth total volume is calculated; and if the rate of change is greater than the preset second upper limit, it is determined that the beam output parameters obtained in step 401 need to be changed.

[0146] In an optional embodiment, in step 405, comparing the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image further includes:

[0147] If the radiotherapy region of interest is a lesion, a maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the target area of the CT image. If the maximum value is greater than a preset third upper limit, it is determined that the beam delivery parameters obtained in step 401 need to be changed. Alternatively, a coverage of voxel points in the target area of the CT image having a mapped radiation dose greater than a preset first threshold is calculated. If the coverage is less than a preset fourth upper limit, it is determined that the beam delivery parameters obtained in step 401 need to be changed.

[0148] If the radiotherapy area of interest is a critical protected organ, the maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the critical protected organ in the CT image. If the maximum value is greater than the preset fourth upper limit, it is determined that the beam-out parameters obtained in step 401 need to be changed; alternatively, the total volume of voxel points on the critical protected organ in the CT image whose mapped radiation dose is greater than the preset second threshold is calculated. If the total volume is greater than the preset sixth upper limit, it is determined that the beam-out parameters obtained in step 401 need to be changed.

[0149] In an optional embodiment, after determining whether the beam parameters obtained in step 401 need to be changed in step 405, the method further includes: when it is determined that the beam parameters need to be changed, mapping each voxel point on the CBCT image to the CT image, and determining the changed beam parameters based on the position and structure of the lesion on the mapped CT image; and, based on the mapped CT image and the changed beam parameters, obtaining a radiation dose distribution on the mapped CT image, and using the radiation dose distribution on the mapped CT image as the radiation dose distribution currently used for the target tissue.

[0150] An embodiment of the present invention further provides a radiotherapy device, which includes the beam parameter adjustment device 10 of any of the above radiotherapy devices.

[0151] Those skilled in the art will appreciate that the features described in the various embodiments and / or claims disclosed in this application may be combined and / or coupled in various ways, even if such combinations and / or couplings are not explicitly disclosed in this application. In particular, without departing from the spirit and teachings of this application, the features described in the various embodiments and / or claims of this application may be combined and / or coupled in various ways, and all such combinations and / or couplings fall within the scope disclosed in this application.

[0152] Specific embodiments are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core ideas of the present application and is not intended to limit the present application. For those skilled in the art, changes can be made in the specific implementation methods and application scope based on the ideas, spirit and principles of the present application. Any modifications, equivalent replacements, improvements, etc. made by them should be included in the scope of protection of this application.

Claims

1. A beam parameter adjustment device for radiotherapy equipment, characterized in that: The device includes: A beam parameter acquisition module is used to acquire a computed tomography (CT) image of the target tissue and to obtain beam parameters of the radiotherapy device determined based on the location and structure of the lesion in the CT image. an initial radiation dose acquisition module, which acquires the radiation dose distribution on the CT image, wherein the radiation dose distribution on the CT image is calculated based on the CT image and the beam output parameters; a cone-beam computed tomography (CBCT) image acquisition module, which acquires one or more CBCT images of the target tissue, wherein the one or more CBCT images are acquired after the CT image, and different CBCT images are acquired at different times; an intermediate radiation dose acquisition module, which acquires the radiation dose distribution on each CBCT image, wherein, for each CBCT image, the radiation dose distribution on the CBCT image is calculated based on the CBCT image and the beam output parameters; The beam parameter adjustment decision module maps the radiation dose of each voxel point on each CBCT image to the corresponding voxel point on the CT image, and compares the mapped radiation dose distribution of each radiotherapy area of interest in the CT image with the original radiation dose distribution of each radiotherapy area of interest in the CT image to determine whether the beam parameter needs to be changed.

2. The device according to claim 1, characterized in that After acquiring one or more CBCT images of the target tissue, the CBCT image acquisition module is further configured to: For each CBCT image, register the CBCT image with the CT image based on bone markers, and determine the position and structure of each radiotherapy region of interest on the CBCT image based on the registration result, wherein the radiotherapy region of interest includes: the lesion and each important protected organ; Furthermore, after acquiring the radiation dose distribution on each CBCT image, the intermediate radiation dose acquisition module is further configured to: For each CBCT image, the radiation dose distribution of each radiotherapy region of interest on the CBCT image is determined based on the radiation dose distribution on the CBCT image and the position and structure of each radiotherapy region of interest on the CBCT image.

3. The device according to claim 1, characterized in that When there is only one CBCT image, the beam parameter adjustment decision module compares the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image, including: If the radiotherapy area of interest is a lesion, calculating, based on the mapped radiation dose distribution of the target area in the CT image, a first total volume of voxel points in the target area of the CT image having a mapped radiation dose greater than a preset first threshold value; calculating, based on the original radiation dose distribution of the target area in the CT image, a second total volume of voxel points in the target area of the CT image having an original radiation dose greater than the preset first threshold value; calculating a rate of change of the first total volume relative to the second total volume; and, if the rate of change is greater than a preset first upper limit, determining that the beam output parameters need to be changed; If the radiotherapy area of interest is a vital protected organ, based on the mapped radiation dose distribution of the vital protected organ in the CT image, calculate the third total volume of voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than a preset second threshold; based on the original radiation dose distribution of the vital protected organ in the CT image, calculate the fourth total volume of voxel points on the vital protected organ in the CT image whose original radiation dose is greater than the preset second threshold; calculate the rate of change of the third total volume relative to the fourth total volume; and if the rate of change is greater than the preset second upper limit, determine that the beam output parameters need to be changed.

4. The device according to claim 3, characterized in that The beam parameter adjustment decision module compares the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image, and is further configured to: If the radiotherapy region of interest is a lesion, finding a maximum value of the mapped radiation dose in the mapped radiation dose distribution of the target area of the CT image, and if the maximum value is greater than a preset third upper limit, determining that the beam delivery parameters need to be changed; or calculating coverage of voxel points in the target area of the CT image whose mapped radiation dose is greater than a preset first threshold, and if the coverage is less than a preset fourth upper limit, determining that the beam delivery parameters need to be changed; If the radiotherapy area of interest is a vital protected organ, the maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the vital protected organ in the CT image, and if the maximum value is greater than the preset fifth upper limit, it is determined that the beam-out parameters need to be changed; alternatively, the total volume of voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than the preset second threshold is calculated, and if the total volume is greater than the preset sixth upper limit, it is determined that the beam-out parameters need to be changed.

5. The device according to claim 1, characterized in that When there are multiple CBCT images, the beam parameter adjustment decision module compares the mapped radiation dose distribution of each radiotherapy area of interest in the CT image with the original radiation dose distribution of each radiotherapy area of interest in the CT image, including: If the radiotherapy area of interest is a lesion, for each voxel point on the target area of the CT image, an average of the mapped radiation doses of each CBCT image mapped to the voxel point of the CT image is calculated, and the average is used as the mapped radiation dose of the voxel point of the CT image. Then, based on the mapped radiation dose distribution of the target area of the CT image, a fifth total volume of voxels in the target area of the CT image having a mapped radiation dose greater than a preset first threshold is calculated; based on the original radiation dose distribution of the target area of the CT image, a sixth total volume of voxels in the target area of the CT image having an original radiation dose greater than the preset first threshold is calculated; a change rate of the fifth total volume relative to the sixth total volume is calculated; and if the change rate is greater than a preset first upper limit, it is determined that the beam output parameters need to be changed; If the radiotherapy area of interest is a vital protected organ, for each voxel point on the vital protected organ in the CT image, the average of the mapped radiation doses of each CBCT image mapped to the voxel point in the CT image is calculated, and the average is used as the mapped radiation dose of the voxel point in the CT image. Then, based on the mapped radiation dose distribution of the vital protected organ in the CT image, the seventh total volume of the voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than a preset second threshold is calculated; based on the original radiation dose distribution of the vital protected organ in the CT image, the eighth total volume of the voxel points on the vital protected organ whose original radiation dose is greater than the preset second threshold is calculated; the rate of change of the seventh total volume relative to the eighth total volume is calculated; and if the rate of change is greater than a preset second upper limit, it is determined that the beam output parameters need to be changed.

6. The device according to claim 5, characterized in that The beam parameter adjustment decision module compares the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image, and is further configured to: If the radiotherapy region of interest is a lesion, finding a maximum value of the mapped radiation dose in the mapped radiation dose distribution of the target area of the CT image, and if the maximum value is greater than a preset third upper limit, determining that the beam delivery parameters need to be changed; or calculating coverage of voxel points in the target area of the CT image whose mapped radiation dose is greater than a preset first threshold, and if the coverage is less than a preset fourth upper limit, determining that the beam delivery parameters need to be changed; If the radiotherapy area of interest is a vital protected organ, the maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the vital protected organ in the CT image, and if the maximum value is greater than the preset fourth upper limit, it is determined that the beam-out parameters need to be changed; or, the total volume of voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than the preset second threshold is calculated, and if the total volume is greater than the preset sixth upper limit, it is determined that the beam-out parameters need to be changed.

7. The device according to claim 1, characterized in that After the beam-out parameter adjustment decision module determines whether the beam-out parameter needs to be changed, it is further configured to: When it is determined that the beam emission parameters need to be changed, each voxel point on the CBCT image is mapped onto the CT image, and the changed beam emission parameters are determined based on the position and structure of the lesion on the mapped CT image; and, based on the mapped CT image and the changed beam emission parameters, a radiation dose distribution on the mapped CT image is obtained, and the radiation dose distribution on the mapped CT image is used as the radiation dose distribution currently applied to the target tissue.

8. A method for adjusting beam parameters of a radiotherapy device, characterized in that: The method includes: Acquire a computed tomography (CT) image of the target tissue; obtain beam parameters of a radiotherapy device determined based on the location and structure of the lesion in the CT image; Acquiring a radiation dose distribution on a CT image, wherein the radiation dose distribution on the CT image is calculated based on the CT image and the beam output parameters; Acquiring one or more cone-beam computed tomography (CBCT) images of the target tissue, wherein the one or more CBCT images are acquired after the CT image, and different CBCT images are acquired at different times; Acquiring a radiation dose distribution on each CBCT image, wherein for each CBCT image, the radiation dose distribution on the CBCT image is calculated based on the CBCT image and the beam output parameters; For each CBCT image, the radiation dose of each voxel point on the CBCT image is mapped to the corresponding voxel point of the CT image, and the mapped radiation dose distribution of each radiotherapy area of interest in the CT image is compared with the original radiation dose distribution of each radiotherapy area of interest in the CT image to determine whether the beam parameters need to be changed.

9. The method according to claim 8, characterized in that After acquiring one or more CBCT images of the target tissue and before acquiring the radiation dose distribution on each CBCT image, the method further includes: For each CBCT image, register the CBCT image with the CT image based on bone markers, and determine the position and structure of each radiotherapy region of interest on the CBCT image based on the registration result, wherein the radiotherapy region of interest includes: the lesion and each important protected organ; Furthermore, after acquiring the radiation dose distribution on each CBCT image and before comparing the radiation dose distribution on the one or more CBCT images with the radiation dose distribution on the CT image, the method further includes: For each CBCT image, the radiation dose distribution of each radiotherapy region of interest on the CBCT image is determined based on the radiation dose distribution on the CBCT image and the position and structure of each radiotherapy region of interest on the CBCT image.

10. The method according to claim 8, characterized in that When there is only one CBCT image, comparing the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image includes: If the radiotherapy area of interest is a lesion, calculating, based on the mapped radiation dose distribution of the target area in the CT image, a first total volume of voxel points in the target area of the CT image having a mapped radiation dose greater than a preset first threshold value; calculating, based on the original radiation dose distribution of the target area in the CT image, a second total volume of voxel points in the target area of the CT image having an original radiation dose greater than the preset first threshold value; calculating a rate of change of the first total volume relative to the second total volume; and, if the rate of change is greater than a preset first upper limit, determining that the beam output parameters need to be changed; If the radiotherapy area of interest is a vital protected organ, based on the mapped radiation dose distribution of the vital protected organ in the CT image, calculate the third total volume of voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than a preset second threshold; based on the original radiation dose distribution of the vital protected organ in the CT image, calculate the fourth total volume of voxel points on the vital protected organ in the CT image whose original radiation dose is greater than the preset second threshold; calculate the rate of change of the third total volume relative to the fourth total volume; and if the rate of change is greater than the preset second upper limit, determine that the beam output parameters need to be changed.

11. The method according to claim 10, characterized in that The comparing the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image further comprises: If the radiotherapy region of interest is a lesion, finding a maximum value of the mapped radiation dose in the mapped radiation dose distribution of the target area of the CT image, and if the maximum value is greater than a preset third upper limit, determining that the beam delivery parameters need to be changed; or calculating coverage of voxel points in the target area of the CT image whose mapped radiation dose is greater than a preset first threshold, and if the coverage is less than a preset fourth upper limit, determining that the beam delivery parameters need to be changed; If the radiotherapy area of interest is a vital protected organ, the maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the vital protected organ in the CT image, and if the maximum value is greater than the preset fifth upper limit, it is determined that the beam-out parameters need to be changed; alternatively, the total volume of voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than the preset second threshold is calculated, and if the total volume is greater than the preset sixth upper limit, it is determined that the beam-out parameters need to be changed.

12. The method according to claim 8, characterized in that When there are multiple CBCT images, comparing the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image includes: If the radiotherapy area of interest is a lesion, for each voxel point on the target area of the CT image, an average of the mapped radiation doses of each CBCT image mapped to the voxel point of the CT image is calculated, and the average is used as the mapped radiation dose of the voxel point of the CT image. Then, based on the mapped radiation dose distribution of the target area of the CT image, a fifth total volume of voxels in the target area of the CT image having a mapped radiation dose greater than a preset first threshold is calculated; based on the original radiation dose distribution of the target area of the CT image, a sixth total volume of voxels in the target area of the CT image having an original radiation dose greater than the preset first threshold is calculated; a change rate of the fifth total volume relative to the sixth total volume is calculated; and if the change rate is greater than a preset first upper limit, it is determined that the beam output parameters need to be changed; If the radiotherapy area of interest is a vital protected organ, for each voxel point on the vital protected organ in the CT image, the average of the mapped radiation doses of each CBCT image mapped to the voxel point in the CT image is calculated, and the average is used as the mapped radiation dose of the voxel point in the CT image. Then, based on the mapped radiation dose distribution of the vital protected organ in the CT image, the seventh total volume of the voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than a preset second threshold is calculated; based on the original radiation dose distribution of the vital protected organ in the CT image, the eighth total volume of the voxel points on the vital protected organ whose original radiation dose is greater than the preset second threshold is calculated; the rate of change of the seventh total volume relative to the eighth total volume is calculated; and if the rate of change is greater than a preset second upper limit, it is determined that the beam output parameters need to be changed.

13. The method according to claim 12, characterized in that The comparing the mapped radiation dose distribution of each radiotherapy region of interest in the CT image with the original radiation dose distribution of each radiotherapy region of interest in the CT image further comprises: If the radiotherapy region of interest is a lesion, finding a maximum value of the mapped radiation dose in the mapped radiation dose distribution of the target area of the CT image, and if the maximum value is greater than a preset third upper limit, determining that the beam delivery parameters need to be changed; or calculating coverage of voxel points in the target area of the CT image whose mapped radiation dose is greater than a preset first threshold, and if the coverage is less than a preset fourth upper limit, determining that the beam delivery parameters need to be changed; If the radiotherapy area of interest is a vital protected organ, the maximum value of the mapped radiation dose is found in the mapped radiation dose distribution of the vital protected organ in the CT image, and if the maximum value is greater than the preset fourth upper limit, it is determined that the beam-out parameters need to be changed; or, the total volume of voxel points on the vital protected organ in the CT image whose mapped radiation dose is greater than the preset second threshold is calculated, and if the total volume is greater than the preset sixth upper limit, it is determined that the beam-out parameters need to be changed.

14. The method according to claim 8, characterized in that After determining whether the beam-emitting parameters need to be changed, the method further includes: When it is determined that the beam emission parameters need to be changed, each voxel point on the CBCT image is mapped onto the CT image, and the changed beam emission parameters are determined based on the position and structure of the lesion on the mapped CT image; and, based on the mapped CT image and the changed beam emission parameters, a radiation dose distribution on the mapped CT image is obtained, and the radiation dose distribution on the mapped CT image is used as the radiation dose distribution currently applied to the target tissue.

15. A radiotherapy device, characterized in that: The device comprises the beam parameter adjustment device of the radiotherapy device according to any one of claims 1 to 7.

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