Geometric calibration method and system of radiotherapy image system and storage medium

Abstract

The invention discloses a geometric calibration method and system for a radiotherapy image system and a storage medium, and the method comprises the steps: generating a digital motif through employing the known geometric parameters of a geometric calibration motif; acquiring an actual projection image of the radiotherapy image system on the geometric calibration phantom, and reconstructing the actual projection image to generate a three-dimensional phantom image; registering the reconstructed three-dimensional motif image with the digital motif by using an image registration algorithm to obtain a registered theoretical digital motif; based on parameters of a radiotherapy image system, orthographically projecting the registered digital motif into theoretical projection images at different angles; calculating the offset between the actual projection image acquired by the radiotherapy image system and the theoretical projection image; and obtaining geometric correction parameters of the radiotherapy image system based on the offset. According to the invention, errors caused by inaccurate positioning of the geometric calibration die body can be avoided, and the accuracy, efficiency, flexibility and universality of geometric calibration are improved, so that the treatment effect and safety of radiotherapy are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of image processing, and in particular relates to a geometric calibration method, system and storage medium for a radiotherapy imaging system. Background Art

[0002] With the rapid development of modern medical technology, radiotherapy, as an important means of tumor treatment, relies heavily on the precision and accuracy of radiotherapy equipment for its effectiveness and safety. Among them, the imaging system, as a key component of the radiotherapy device, plays a vital role in accurately determining the location, shape and size of the tumor, thereby formulating an accurate radiotherapy plan and implementing precise treatment. However, the geometric calibration of the imaging system has always been a difficult problem to be solved in the field of radiotherapy.

[0003] Traditional methods for geometric calibration of radiotherapy imaging systems usually rely on manual operation and complex equipment. In terms of manual operation, professional technicians are required to carefully and accurately place the geometric correction phantom. This process not only requires technicians to have superb skills and rich experience, but also requires them to concentrate highly, because any slight deviation may lead to inaccurate calibration results. Moreover, manual operation is often time-consuming and laborious, increasing the manpower and time costs of medical institutions.

[0004] From the perspective of equipment, traditional calibration methods usually rely on high-precision, high-cost dedicated equipment, which is not only expensive to purchase, but also requires a lot of resources to maintain and maintain. In addition, due to the complexity of the equipment, its operation and use often require professional training, which further increases the operating costs of medical institutions.

[0005] In actual operation, traditional methods still have many technical difficulties. For example, due to the complexity and diversity of human tissues and the physical characteristics of radiotherapy equipment itself, it is difficult to obtain accurate imaging data. At the same time, changes in environmental factors such as temperature and humidity may also affect the performance of the imaging system, resulting in errors in geometric calibration.

[0006] In addition, traditional geometric calibration methods often lack flexibility and versatility when dealing with different types of radiotherapy equipment and different tumor cases. For some special cases or new radiotherapy equipment, the existing calibration methods may not meet the needs and require a lot of customized development and debugging, which undoubtedly increases the difficulty and uncertainty of treatment.

[0007] More importantly, traditional methods are insufficient in terms of accuracy and reliability. Uncertainties caused by manual operation, equipment limitations, and complex environmental factors may lead to inaccurate geometric calibration results, which in turn affects the effectiveness and safety of radiotherapy. Inaccurate geometric calibration may cause the radiotherapy rays to fail to focus accurately on the tumor site, which not only reduces the treatment effect, but also may cause unnecessary damage to surrounding normal tissues, increasing the patient's pain and treatment risks.

[0008] In summary, the existing geometric calibration methods of radiotherapy device imaging systems have many disadvantages such as complex operation, high cost, insufficient accuracy, lack of versatility and flexibility, which seriously restrict the development and application of radiotherapy technology. An innovative, efficient and accurate geometric calibration method is urgently needed to solve these problems. Summary of the invention

[0009] In order to solve the above technical problems, the present invention proposes a geometric calibration method, system and storage medium for a radiotherapy imaging system.

[0010] In order to achieve the above object, the technical solution of the present invention is as follows:

[0011] In a first aspect, the present invention discloses a method for geometric calibration of a radiotherapy imaging system, comprising:

[0012] Step S1: Generate a digital phantom using known geometric parameters of the geometric calibration phantom;

[0013] Step S2: obtaining the actual projection image of the geometric calibration phantom by the radiotherapy imaging system, and reconstructing it to generate a three-dimensional phantom image;

[0014] Step S3: using an image matching algorithm to register the reconstructed three-dimensional phantom image with the digital phantom to obtain a registered theoretical digital phantom;

[0015] Step S4: Based on the parameters of the radiotherapy imaging system, the registered digital phantom is orthographically projected into theoretical projection images at different angles;

[0016] Step S5: calculating the offset between the actual projection image acquired by the radiotherapy imaging system and the theoretical projection image;

[0017] Step S6: Based on the offset, obtain the geometric correction parameters of the radiotherapy imaging system.

[0018] Based on the above technical solution, the following improvements can be made:

[0019] As a preferred solution, the geometric calibration model is a cylinder, and a calibration main column and four calibration sub-columns with the same structure are provided on the geometric calibration model, and the calibration main column and the calibration sub-columns respectively include: a number of metal balls equidistantly distributed in the geometric calibration model along the axis of the geometric calibration model;

[0020] The calibration main column is distributed at the central axis of the geometric calibration model, and the four calibration sub-columns are distributed outside the calibration main column, and the connecting lines of the two diagonally arranged calibration sub-columns are perpendicular to each other.

[0021] As a preferred embodiment, the known geometric parameters include one or more of the following data: the height of the geometric calibration phantom, the diameter of the geometric calibration phantom, the distance between adjacent metal balls in the calibration main column, the distance from the outermost metal ball in the calibration main column to the end plane of the geometric calibration phantom, the distance between adjacent metal balls in the calibration sub-column, the distance from the outermost metal ball in the calibration sub-column to the end plane of the geometric calibration phantom, and the distance between the calibration main column and the calibration sub-column.

[0022] As a preferred solution, the distance from each calibrated sub-column to the calibrated main column is equal.

[0023] As a preferred solution, the calibration main column includes: three metal balls equidistantly distributed along the axis of the geometric calibration phantom;

[0024] Each calibration column includes: two metal balls equidistantly distributed along the axis of the geometric calibration phantom.

[0025] As a preferred solution, in the calibration main column, the spacing between adjacent metal balls is m, and the distance from the outermost metal ball to the end plane of the geometric calibration phantom is n, n<m;

[0026] In the calibration column, the distance between adjacent metal balls is m, and the distance from the outermost metal ball to the end plane of the geometric calibration model is m / 2+n.

[0027] As a preferred solution, the distance between the calibration main column and any calibration sub-column is at least m / 2.

[0028] In a second aspect, the present invention discloses a geometric calibration system for a radiotherapy imaging system, comprising: a radiotherapy beam delivery device, a detection device, a treatment bed, and a geometric calibration phantom;

[0029] The geometric calibration system is used to execute any of the above-mentioned geometric calibration methods.

[0030] As a preferred solution, the geometric calibration phantom is connected to the phantom driving device, and the phantom driving device is used to

[0031] During calibration, the geometric calibration phantom is extended and sent to the calibration position, which is the rotation center position of the radiotherapy imaging system;

[0032] When not in calibration mode, retract the geometric calibration phantom to the storage position under the treatment bed.

[0033] In a third aspect, the present invention discloses a storage medium, characterized in that the storage medium stores one or more computer-readable programs, and the one or more programs include instructions, and the instructions are suitable for being loaded by a memory and executing any of the above-mentioned geometric calibration methods.

[0034] The present invention discloses a geometric calibration method, system and storage medium for a radiotherapy imaging system, which can automatically perform geometric correction, get rid of dependence on manual intervention, reduce manpower and material costs, avoid errors caused by inaccurate positioning of geometric calibration phantoms, and improve the accuracy, efficiency, flexibility and versatility of geometric calibration, thereby enhancing the therapeutic effect and safety of radiotherapy. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 A flowchart of a geometric calibration method provided in an embodiment of the present invention.

[0037] Figure 2 A schematic diagram of the structure of a geometric calibration phantom provided in an embodiment of the present invention.

[0038] Figure 3 A cross-sectional view of a geometric calibration phantom provided in an embodiment of the present invention.

[0039] Figure 4 A bottom view of a geometric calibration phantom provided in an embodiment of the present invention.

[0040] Figure 5 A cross-sectional view (with annotations) of a geometric calibration phantom provided in an embodiment of the present invention.

[0041] Figure 6 A bottom view (with annotations) of a geometric calibration phantom provided in an embodiment of the present invention.

[0042] Figure 7 A schematic diagram of the structure of a geometric calibration system (during calibration) provided in an embodiment of the present invention.

[0043] Figure 8 A schematic diagram of the structure of a geometric calibration system (non-calibration) provided in an embodiment of the present invention.

[0044] Among them: 1-geometric calibration phantom, 11-calibration main column, 21-first calibration sub-column, 22-second calibration sub-column, 23-third calibration sub-column, 24-fourth calibration sub-column, 13-metal sphere, 2-radiotherapy beam output device, 3-detection device, 4-treatment bed, 5-phantom driving device. DETAILED DESCRIPTION

[0045] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Using ordinal numbers “first,” “second,” “third,” etc. to describe common objects merely indicates that different instances of similar objects are involved and is not intended to imply that the objects so described must have a given order in time, space, order, or in any other manner.

[0048] In addition, the expression of “comprising” an element is an “open” expression, which merely means that corresponding components or steps exist, and should not be interpreted as excluding additional components or steps.

[0049] In order to achieve the purpose of the present invention, in some embodiments of the geometric calibration method, system and storage medium of the radiotherapy imaging system, the geometric calibration method includes:

[0050] Step S1: Generate a digital phantom using known geometric parameters of the geometric calibration phantom, such as Figure 2 As shown;

[0051] The known geometric parameters include one or more of the following data: the height of the geometric calibration phantom, the diameter of the geometric calibration phantom, the distance between adjacent metal balls in the calibration main column, the distance from the outermost metal ball in the calibration main column to the end plane of the geometric calibration phantom, the distance between adjacent metal balls in the calibration sub-column, the distance from the outermost metal ball in the calibration sub-column to the end plane of the geometric calibration phantom, and the distance between the calibration main column and the calibration sub-column;

[0052] Step S2: obtaining the actual projection image of the geometric calibration phantom by the radiotherapy imaging system, and reconstructing it to generate a three-dimensional phantom image;

[0053] Step S3: using an image matching algorithm to register the reconstructed three-dimensional phantom image with the digital phantom to obtain a registered theoretical digital phantom;

[0054] Step S4: Based on the parameters of the radiotherapy imaging system, the registered digital phantom is orthographically projected into theoretical projection images at different angles;

[0055] Step S5: calculating the offset between the actual projection image acquired by the radiotherapy imaging system and the theoretical projection image;

[0056] Step S6: Based on the offset, obtain the geometric correction parameters of the radiotherapy imaging system.

[0057] Each step is further explained below.

[0058] Step S1 uses known geometry to calibrate the geometric parameters of the phantom to generate a highly accurate and stable digital phantom that can detect image deformation caused by various possible image features and parameter changes, thereby providing an extremely reliable benchmark for subsequent correction work.

[0059] The geometric calibration phantom is placed at the rotation center of the radiotherapy imaging system, and then step S2 is performed. Step S2 is a step for reconstructing the actual projection image.

[0060] In step S3, the scanned and reconstructed three-dimensional model image is finely aligned with the digital model through image matching technology to ensure accurate alignment under different resolutions and complex scenes.

[0061] Since the present invention adopts a registration operation, this operation enables effective geometric calibration to be achieved in step S2 when placing the geometric calibration phantom even if the phantom deviates from the rotation center in multiple degrees of freedom.

[0062] In step S4, after obtaining the detailed parameters of the radiotherapy imaging system, the registered digital phantom is orthographically projected into theoretical projection images at different angles.

[0063] Step S5 automatically calculates the offset between the actual projection image and the theoretical projection image acquired by each radiotherapy imaging system. The offset not only takes into account the difference at the pixel level, but also integrates the overall structure and feature information of the image to ensure the comprehensiveness and accuracy of the error assessment.

[0064] Step S6 obtains geometric correction parameters based on the accurately calculated offset. These parameters can be directly applied to the adjustment and optimization of the radiotherapy imaging system to achieve efficient and accurate geometric calibration.

[0065] The present invention discloses a geometric calibration method, each step of which is closely connected and cooperates with each other. The method can be used for calibration of a kilovolt imaging system or a megavolt imaging system, and has the following beneficial effects:

[0066] First, the fully automated process of the present invention does not require manual and careful placement of geometric calibration models, which greatly reduces dependence on manual operations, reduces errors caused by human factors, and saves a lot of manpower and time costs.

[0067] Second, the present invention gets rid of the dependence on high-precision, high-cost special equipment, reduces the equipment purchase, maintenance and upkeep costs of medical institutions, and reduces the operational burden.

[0068] Third, it can more effectively obtain accurate image data, reduce the adverse effects of human tissue complexity, equipment physical characteristics, and environmental factors on geometric calibration, and thus significantly improve the accuracy of calibration.

[0069] Fourth, it has excellent flexibility and versatility, and can adapt to various types of radiotherapy equipment and different tumor cases, without the need for a lot of customized development and debugging, reducing the difficulty and uncertainty of treatment.

[0070] Fifth, the accuracy and reliability of geometric calibration have been greatly improved, effectively avoiding the problem of inaccurate calibration results caused by manual operation uncertainty, equipment limitations and complex environmental factors, significantly improving the therapeutic effect and safety of radiotherapy, reducing damage to the patient's normal tissues, and reducing the patient's pain and treatment risks.

[0071] In order to further optimize the implementation effect of the present invention, in some other embodiments, the remaining characteristic technologies are the same, except that, Figure 2-6 As shown, the geometric calibration phantom 1 is a cylinder, and a calibration main column 11 and four calibration sub-columns with the same structure (specifically: a first calibration sub-column 121, a second calibration sub-column 122, a third calibration sub-column 123, and a fourth calibration sub-column 124) are provided on the geometric calibration phantom 1. The calibration main column 11 and each calibration sub-column respectively include: a plurality of metal balls 13 equidistantly distributed in the geometric calibration phantom 1 along the axis of the geometric calibration phantom;

[0072] The calibration main column 11 is distributed at the central axis of the geometric calibration model 1, and the four calibration sub-columns are distributed on the outside of the calibration main column 11, and the connecting lines of the two diagonally arranged calibration sub-columns are perpendicular to each other (that is, the connecting line AB between the first calibration sub-column 121 and the third calibration sub-column 123 is orthogonal to the connecting line CD between the second calibration sub-column 122 and the fourth calibration sub-column 124).

[0073] Further, the calibration main column 11 includes: three metal balls 13 equidistantly distributed along the axis of the geometric calibration phantom 1;

[0074] Each calibration column includes two metal balls 13 equidistantly distributed along the axis of the geometric calibration phantom 1 .

[0075] The total height of the geometric calibration phantom is H, and the diameter is D.

[0076] Furthermore, in the calibration main column 11, the spacing between adjacent metal balls 13 is m, and the distance between the outermost metal ball 13 and the end plane of the geometric calibration phantom 1 is n, where n<m;

[0077] 2m+2n=H;

[0078] In the calibration column, the spacing between adjacent metal balls 13 is m, and the distance from the outermost metal ball 13 to the end plane of the geometric calibration phantom 1 is m / 2+n.

[0079] Furthermore, the distance from each calibration sub-column to the calibration main column 1 is equal, and the distance between the calibration main column 1 and any calibration sub-column is at least m / 2.

[0080] It is worth noting that the number of metal balls in the geometric calibration phantom 1 can be other numbers or distributions, but it must be ensured that there is no overlap of metal balls when the phantom step S1 is imaged at 360 degrees.

[0081] The geometric calibration phantom disclosed in the above embodiments can test geometric deformations in multiple dimensions.

[0082] In this embodiment, the known geometric parameters in the above step S1 are H, D, m and n.

[0083] The embodiment of the present invention further discloses a geometric calibration system for a radiotherapy imaging system, comprising: a radiotherapy beam emitting device 2, a detection device 3, a treatment bed 4 and a geometric calibration phantom 1;

[0084] The geometric calibration system is used to execute the geometric calibration method disclosed in the above embodiment.

[0085] Furthermore, in some embodiments, the geometric calibration phantom is in transmission connection with the phantom driving device 5, and the phantom driving device 5 is used to

[0086] During calibration, the geometric calibration phantom 1 is extended to the calibration position, which is the rotation center position of the radiotherapy imaging system. Figure 7 As shown;

[0087] When not calibrating, the geometric calibration phantom 1 is retracted to the storage position below the treatment bed 4, such as Figure 8 shown.

[0088] During calibration, the bed board of the treatment bed is moved backward and the position of the bed is raised, and the phantom driving device extends the geometric calibration phantom to the rotation center position of the radiotherapy imaging system.

[0089] Furthermore, an embodiment of the present invention also discloses a storage medium, characterized in that the storage medium stores one or more computer-readable programs, and the one or more programs include instructions, and the instructions are suitable for being loaded by a memory and executing the geometric calibration method disclosed in any of the above embodiments.

[0090] The present invention discloses a geometric calibration method, system and storage medium for a radiotherapy imaging system, which can automatically perform geometric correction, get rid of dependence on manual intervention, reduce manpower and material costs, avoid errors caused by inaccurate positioning of geometric calibration phantoms, and improve the accuracy, efficiency, flexibility and versatility of geometric calibration, thereby enhancing the therapeutic effect and safety of radiotherapy.

[0091] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which shall fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A geometric calibration method for a radiotherapy imaging system, characterized in that: include: Step S1: Generate a digital phantom using known geometric parameters of the geometric calibration phantom; Step S2: obtaining the actual projection image of the geometric calibration phantom by the radiotherapy imaging system, and reconstructing it to generate a three-dimensional phantom image; Step S3: using an image matching algorithm to register the reconstructed three-dimensional phantom image with the digital phantom to obtain a registered theoretical digital phantom; Step S4: Based on the parameters of the radiotherapy imaging system, the registered digital phantom is orthographically projected into theoretical projection images at different angles; Step S5: calculating the offset between the actual projection image acquired by the radiotherapy imaging system and the theoretical projection image; Step S6: Based on the offset, obtain the geometric correction parameters of the radiotherapy imaging system.

2. The geometric calibration method according to claim 1, characterized in that: The geometric calibration model is a cylinder, and is provided with a calibration main column and four calibration sub-columns with the same structure, wherein the calibration main column and the calibration sub-columns respectively include: a plurality of metal balls equidistantly distributed in the geometric calibration model along the axis of the geometric calibration model; The calibration main column is distributed at the central axis of the geometric calibration model, and the four calibration sub-columns are distributed outside the calibration main column, and the connecting lines of the two diagonally arranged calibration sub-columns are perpendicular to each other.

3. The geometric calibration method according to claim 2, characterized in that: The known geometric parameters include one or more of the following data: the height of the geometric calibration phantom, the diameter of the geometric calibration phantom, the distance between adjacent metal balls in the calibration main column, the distance from the outermost metal ball in the calibration main column to the end plane of the geometric calibration phantom, the distance between adjacent metal balls in the calibration sub-column, the distance from the outermost metal ball in the calibration sub-column to the end plane of the geometric calibration phantom, and the distance between the calibration main column and the calibration sub-column.

4. The geometric calibration method according to claim 3, characterized in that: The distance from each of the calibrated sub-columns to the calibrated main column is equal.

5. The geometric calibration method according to claim 2, characterized in that: The calibration main column includes: three metal balls equidistantly distributed along the axis of the geometric calibration phantom; Each of the calibration columns comprises: two metal balls equidistantly distributed along the axis of the geometric calibration phantom.

6. The geometric calibration method according to claim 5, characterized in that: In the calibration main column, the spacing between adjacent metal balls is m, and the distance from the outermost metal ball to the end plane of the geometric calibration phantom is n, where n<m; In the calibration column, the spacing between adjacent metal balls is m, and the distance from the outermost metal ball to the end plane of the geometric calibration model is m / 2+n.

7. The geometric calibration method according to claim 2, characterized in that: The distance between the calibrated main column and any calibrated sub-column is at least m / 2.

8. A geometric calibration system for a radiotherapy imaging system, characterized in that: include: Radiotherapy beam delivery device, detection device, treatment bed and geometric calibration phantom; Used to execute the geometric calibration method as described in any one of claims 1-7.

9. The geometric calibration system according to claim 8, characterized in that: The geometric calibration phantom is in driving connection with a phantom driving device, and the phantom driving device is used to During calibration, the geometric calibration phantom is extended to a calibration position, where the calibration position is the rotation center position of the radiotherapy imaging system; When not in calibration mode, retract the geometric calibration phantom to the storage position under the treatment bed.

10. A storage medium, characterized in that The storage medium stores one or more computer-readable programs, and the one or more programs include instructions, and the instructions are suitable for being loaded by the memory and executing the geometric calibration method described in any one of claims 1 to 8.

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