Multi-leaf collimator with convex tail-end leaf and leaf design method

Abstract

The invention provides a multi-blade collimator with convex tail end blades and a design method of the blades. Each blade comprises a strip-shaped body and a convex tail end. And the convex tail end is arranged at the end part of the blade. Along the width direction of the blade, the tail end of the blade is a curve symmetrical along the center line of the blade. Along the height direction of the blade, the tail end of the convex shape is formed by overlapping the sections of the width shapes. By means of the convex tail end, the blades at any position form convex projections consistent in shape and size on the isocenter plane. The convex projection can better fit a tumor edge curve, so that the problem of insufficient conformity between the projection shape of a traditional blade and the edge of a tumor target region is solved, and the treatment effect is improved. Meanwhile, a method for designing a blade entity according to blade projection and a method for calculating an optimal tail end projection shape are provided, and after a blade model is constructed, the blade is applied to the multi-layer multi-blade collimator. Through the multiple layers of blades, ray leakage of a gap between every two adjacent convex blades can be avoided, the conformity is improved, and the treatment effect is improved.

Description

Technical Field

[0001] The present application relates to the technical field of medical equipment, and in particular to a multi-leaf collimator with convex end blades and a design method for the blades. Background Art

[0002] Multileaf Collimator (MLC) is an important component used in radiotherapy equipment. Multileaf collimator can form field holes of different shapes to limit the radiation range of the radiation beam emitted by the radiation source, so that tumors can be treated while protecting the surrounding normal tissues. The more conformal the shape of the field hole formed by the radiation passing through the multileaf collimator on the treatment plane is to the shape of the tumor, the more accurate the radiation range of the radiation beam is, and the better the treatment effect is.

[0003] A multi-leaf collimator includes multiple leaves. A leaf is a cube consisting of three parameters: length, width, and height. The length is determined by the range of the radiation field. The height is determined by the material's attenuation effect on the radiation beam. The width determines the conformal effect of the multi-leaf collimator. In the past, one way to improve the conformal effect of a multi-leaf collimator was to narrow the width of the multi-leaf collimator leaves, but there is a physical lower limit to the leaf width and it cannot be narrowed infinitely.

[0004] In the related art, the tip of the leaf is a straight edge, and the projection on the isocenter plane is a rectangle. Therefore, the edge of the radiation field shape formed by multiple leaves is stepped. At the same time, due to the material performance requirements of the leaf, the leaf width cannot be too narrow. The above factors will affect the smoothness of the edge of the radiation field shape. The shape of the tumor is usually formed by an irregular smooth curve, and the tumor boundary can be approximated as a smooth closed curve. Since the step line is very different from the curve, the multi-leaf collimator uses a step line to approximate the shape of the tumor boundary, which is prone to over-irradiation or under-irradiation at the tumor boundary, thus affecting the treatment effect.

[0005] In recent years, in order to improve the performance of multi-leaf collimators, multi-layer multi-leaf collimators have been newly developed. Multi-layer multi-leaf collimators prevent radiation leakage between leaves and improve the resolution of the radiation field formed by staggering the arrangement positions of the upper and lower leaves. However, the leaves of the multi-layer multi-leaf collimator are also designed according to the rectangular projection leaves of the traditional multi-leaf collimator. When fitting the tumor target area, there is also a problem that the stepped edge fits the tumor boundary poorly. Therefore, the multi-leaf collimator needs to improve the conformality by improving the leaf design. Patent CN101000808B designs the projection end shape of the leaf as an inclined straight line and a curve, and proposes an optimization method to optimize the end shape. However, the patent does not consider the physical leaf configuration that realizes this projection, and the situation involved is too broad and not very operational. In order to facilitate the optimization solution, the present application proposes a new method for optimizing the shape of the leaf at the convex end, and solves the optimal leaf projection shape. At the same time, the present application proposes a method for designing a leaf configuration based on the leaf projection shape and the clinical treatment requirements of a multi-leaf collimator, and completes the design of a multi-leaf collimator based on the leaf. Summary of the invention

[0006] The present application provides a multi-leaf collimator with convex end blades and a method for designing the blades, which can solve the problem that the ray projection shape formed by the existing multi-leaf collimator is not highly compatible with the edge of the tumor target area, thus affecting the treatment effect.

[0007] On the one hand, the present application provides a multi-leaf collimator with convex end blades, wherein the multi-leaf collimator blades include a strip-shaped body and a convex end, wherein the convex end is arranged at the end of the strip-shaped body along the length direction of the strip-shaped body, and the convex end extends along the height direction of the strip-shaped body, and along the height direction, the cross-sectional area of ​​the convex end in a first central plane is the largest, and along the width direction of the strip-shaped body, the cross-sectional area of ​​the convex end in a second central plane is the largest.

[0008] The multi-leaf collimator with convex end blades provided in the present application has a projection of a curve or a smooth line formed by a straight line and a curve formed after the radiation beam emitted by the radiation source passes through the convex end. Therefore, it can more effectively adapt to the shape of the tumor, which is beneficial to improving the accuracy of radiotherapy and improving the treatment effect.

[0009] According to one embodiment of the present application, along the height direction, the shape of the orthographic projection of the convex end is formed by at least one of a straight line or a curve, and the projection shape of the convex end on the isocenter plane corresponds to the orthographic projection shape of the convex end along the height direction.

[0010] According to an embodiment of the present application, the curve includes an ellipse, a parabola, a trigonometric function curve or a B-spline curve.

[0011] According to one embodiment of the present application, along the width direction, the blade includes a first side surface and a second side surface that are oppositely arranged, and the cross-sectional area of ​​the terminal convex portion gradually increases in the region from the first side surface to the first center plane, and the cross-sectional area of ​​the terminal convex portion gradually decreases in the region from the first center plane to the second side surface;

[0012] Along the height direction, the blade includes a top surface and a bottom surface that are relatively arranged. In the area from the top surface to the second center plane, the cross-sectional area of ​​the terminal convex portion gradually increases, and in the area from the second center plane to the bottom surface, the cross-sectional area of ​​the terminal convex portion gradually decreases.

[0013] According to one embodiment of the present application, along the height direction, the multi-leaf collimator with convex end blades includes at least two layers of collimator devices, the collimator device includes two blade groups arranged opposite to each other along the length direction, the blade group includes a plurality of blades, along the width direction, the plurality of blades are arranged side by side, and there is a gap between two adjacent blades, in two adjacent collimator devices, the gap between two adjacent blades of one layer is arranged corresponding to the blades of the other layer, and along the height direction, the projections formed by the blades of the two adjacent layers of the collimator devices on the isocenter plane are used to jointly fit the shape of the tumor edge.

[0014] According to an embodiment of the present application, in two adjacent collimator devices, along the height direction, the projection of the upper blade group on the isocenter plane is the same in shape and size as the projection of the lower blade group on the isocenter plane.

[0015] According to one embodiment of the present application, when the collimator device is double-layered, along the width direction, the blades located in the upper layer and the blades located in the lower layer are staggered by a distance of half the width of the blades to block the leakage of rays between adjacent blades and between adjacent convex ends, or;

[0016] When the collimator device has three layers, along the width direction, the blades located in the upper layer are staggered with the blades located in the lower layer by a distance of one third of the width of the blades to block radiation leakage between adjacent blades and adjacent convex ends.

[0017] According to one embodiment of the present application, when the collimator device is multi-layered, the shapes of the convex ends of the leaves located in different layers are not completely the same, and the convex ends of different shapes cooperate with each other to fit the shape of the tumor to the maximum extent.

[0018] In a second aspect, the present application provides a blade design method, which includes:

[0019] S101, establishing a ray projection model;

[0020] S102, determining basic parameters of the blade, and inputting the basic parameters into a ray projection model to solve shape parameters of the blade;

[0021] S103, determining the tangency point between the blade and the ray beam according to the basic parameters and shape parameters, so as to determine the position of the projected cross section of the convex end of the blade in the incident direction of the ray source;

[0022] S104, reversely solving the projected shape of the blade at the height of the tangent point according to the projected cross-sectional shape of the blade, the position of the ray source, and the height of the tangent point;

[0023] S105, repeatedly executing S103 and S104 to obtain the projected shapes at multiple tangent point heights;

[0024] S106, arranging the projected cross sections at the heights of the multiple tangent points in order of height positions, connecting the ends of all the projected cross sections with smooth arc surfaces, and connecting the sides of the projected cross sections with straight surfaces to form a three-dimensional structure of the blade with a convex end.

[0025] According to one embodiment of the present application, the blade design method further includes:

[0026] S107, calculating the difference area of ​​the fitted target area under the protrusion degree of the convex end of different shapes by the integral method, and drawing a curve of the total difference area under each projection shape as a function of the protrusion degree;

[0027] S108. Compare the optimal results of different projection shapes, obtain the optimal projection curve category and the optimal protrusion degree, and finally obtain the optimal projection shape.

[0028] In addition to the technical problems solved by the embodiments of the present invention described above, the technical features that constitute the technical solutions, and the beneficial effects brought about by the technical features of the technical solutions, other technical problems that can be solved by the multi-leaf collimator with convex end blades and the blade design method provided by the embodiments of the present invention, other technical features included in the technical solutions, and the beneficial effects brought about by these technical features will be further described in detail in the specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0030] Figure 1 This is a schematic diagram of the axial structure of a blade according to an embodiment of the present application;

[0031] Figure 2 This is a schematic diagram of a top view of a blade according to an embodiment of the present application;

[0032] Figure 3 This is a schematic diagram of the axial structure of a blade according to another embodiment of the present application;

[0033] Figure 4 This is a schematic diagram of a top view of a blade according to another embodiment of the present application;

[0034] Figure 5 This is a schematic diagram of the axial structure of a blade according to another embodiment of the present application;

[0035] Figure 6 This is a schematic diagram of the axial structure of a blade according to another embodiment of the present application;

[0036] Figure 7 This is a schematic diagram of a top view of a blade according to another embodiment of the present application;

[0037] Figure 8 This is a schematic diagram of the axial structure of a multi-leaf collimator with convex end leaves having a double-layer collimator device according to an embodiment of the present application;

[0038] Fig. 9 A schematic diagram of the axial structure of a multi-leaf collimator with convex end leaves according to an embodiment of the present application having a three-layer collimator device;

[0039] Fig.10 A schematic diagram of a radiation field shape formed by leaves with rectangular ends of a multi-leaf collimator with convex end leaves in the related art;

[0040] Fig.11 A schematic diagram of a multi-leaf collimator with convex end leaves according to an embodiment of the present application, which has a radiation field shape formed by convex end leaves of a double-layer collimator device;

[0041] Fig.12 A schematic diagram of a multi-leaf collimator with convex end leaves according to an embodiment of the present application, which has a radiation field shape formed by convex end leaves of a three-layer collimator device;

[0042] Fig.13 A schematic diagram of a partial side view of the structure of a multi-leaf collimator with convex end leaves according to an embodiment of the present application;

[0043] Fig.14 This is a schematic diagram of a top view of a blade according to another embodiment of the present application;

[0044] Fig.15 This is a schematic diagram of the axial structure of a blade in yet another embodiment of the present application;

[0045] Fig.16 This is a schematic diagram of a top view of a blade according to another embodiment of the present application;

[0046] Fig.17 A flow chart of the blade design method of the present application;

[0047] Fig.18A flow chart of a method for calculating an optimal blade projection shape according to the present application;

[0048] Fig.19 This is a comparison diagram of the protrusion degree change curves of three different shapes of convex ends in this application.

[0049] Description of reference numerals:

[0050] 10-Multi-leaf collimator with convex end leaves;

[0051] 100-collimator device;

[0052] 110- blade group;

[0053] 200-blade;

[0054] 201- first side;

[0055] 202- second side;

[0056] 203-top surface;

[0057] 204-Bottom;

[0058] 210-Strip body;

[0059] 220 - convex end;

[0060] 221-transition surface; 222-end;

[0061] X-length direction;

[0062] Y-height direction;

[0063] Z-width direction.

[0064] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0065] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation methods described in the following exemplary embodiments do not represent all implementation methods consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0066] Radiotherapy, also known as radiotherapy, can use high-energy beams emitted by a radiation source to destroy or eliminate malignant cells. Radiotherapy can cure some cancers that only exist in specific parts of the body, and can also be used as an adjuvant treatment.

[0067] Multi-leaf collimator is an important component of radiotherapy. Multi-leaf collimator is usually installed under the treatment head to limit the irradiation range of the beam emitted by the radiation source to form irregular field holes suitable for various tumor shapes. The radiation source can be configured to generate beams such as photons, electrons, protons or other types of radiation, which are not limited in this application.

[0068] It can be understood that the more closely the radiation field shape formed by the multi-leaf collimator fits the shape of the tumor, the more accurate the radiation range of the radiation beam will be, and the better the treatment effect will be.

[0069] The multi-leaf collimator includes a plurality of leaves. In the related art, the projection of the leaf tip on the isocenter plane is a rectangle. The isocenter plane may refer to the plane where the tumor region is located. It is understood that the edge of the radiation field shape formed by the leaf tip at the rectangular end on the isocenter plane is in a linear stepped shape.

[0070] However, the applicant found that the shape of the tumor is usually formed by an irregular smooth curve. The tumor boundary can be approximated as a smooth closed curve. Although the radiation field formed by the stepped multi-leaf collimator can also fit the tumor shape, due to the lack of smooth transition at the end, some normal tissue areas cannot be effectively blocked, and it is easy to have more or less irradiation at the tumor boundary, thereby affecting the treatment effect.

[0071] For example, if the shape of the leaf field exceeds the tumor boundary, the gap between the leaf field boundary and the tumor boundary forms an underfitting area. The underfitting area easily leads to an increase in the dose of the radiation beam delivered to the normal tissue area, which, on the one hand, easily leads to an increase in the possibility of toxic and side effects in patients. On the other hand, it will reduce the dose of the radiation beam delivered to the tumor area and reduce the treatment effect.

[0072] Alternatively, the boundary of the leaf projection does not exceed the edge of the tumor, however, the leaf blocks a portion of the dose of the radiation beam that should be delivered to the tumor area, thereby reducing the treatment effect.

[0073] Based on the above problems, the applicant has improved the existing multi-leaf collimator. In the present application, the blades may include a strip-shaped body and a convex end. Along the length direction of the strip-shaped body, the convex end may protrude from one end of the strip-shaped body. Since when the radiation beam is irradiated toward the isocenter plane, the projection formed by the blade that blocks the radiation beam on the isocenter plane is consistent with the shape of the convex end, therefore, the applicant conceives that if the convex end is designed to be a smooth curved structure, or surrounded by multiple planes to form a structure with a smooth transition, then the projection formed by the radiation beam after passing through the convex end is a curve or a smooth line formed by multiple straight lines or curves, so that the shape of the target field can be more effectively adapted, which is beneficial to improving the accuracy of radiotherapy and improving the treatment effect.

[0074] At the same time, based on the technical concept of the above-mentioned convex end structure, the applicant combines this blade design with the multi-layer multi-leaf collimator design to innovate. If the number of blades is increased to two, three or even more layers, the gap between the convex ends of two adjacent blades on the same layer can be filled by the blades of another layer, thereby avoiding the leakage of rays between the leaves. At the same time, since the blades of the multi-layer multi-leaf collimator are arranged in an up-and-down staggered manner, the adjustable blade projection width can be reduced to half of that of a single-layer multi-leaf collimator, which is beneficial to improve the resolution of the multi-leaf collimator to form a smoother edge on the isocenter plane.

[0075] The multi-leaf collimator 10 with convex end blades provided by the present application will be described below with reference to the accompanying drawings and in combination with specific embodiments.

[0076] See also Figures 1 to 16 As shown, the multi-leaf collimator 10 of the convex end blade of the embodiment of the present application includes a blade 200. The blade 200 includes a strip body 210 and a convex end 220. Along the length direction X of the strip body 210, the convex end 220 is arranged at the end 222 of the strip body 210. The convex end 220 extends along the height direction Y of the strip body 210. Along the height direction Y, the cross-sectional area of ​​the convex end 220 in the first central plane M is the largest. Along the width direction Z of the strip body 210, the cross-sectional area of ​​the convex end 220 in the second central plane N is the largest.

[0077] It should be noted that, along the height direction Y, the first center plane M is located in the middle area of ​​the strip-shaped body 210 . Along the width direction Z, the second center plane N is located in the middle area of ​​the strip-shaped body 210 .

[0078] See also Figures 1 to 7As shown, the convex end 220 of the present application can be protruded and arranged at one end of the strip body 210. The convex end 220 of the present application can be a smooth curved surface structure, or can be surrounded by multiple planes to form a transitionally smooth structure, and further, a smooth structure can be formed by a plane and a curved surface. The specific structure of the convex end 220 is not limited in the embodiment of the present application.

[0079] The projection formed by the radiation beam emitted by the radiation source after passing through the convex end 220 of the present application can be a smooth line formed by straight lines and curves, so it can more effectively adapt to the shape of the tumor, which is beneficial to improving the accuracy of radiotherapy and improving the treatment effect.

[0080] In some examples, the convex end 220 and the strip body 210 may be an integrally formed structure.

[0081] In some examples, the material of the blade 200 may include heavy metal materials such as tungsten alloy, which is not limited in the present application.

[0082] In some possible implementations, see Figures 1 to 7 As shown in the figure, the shape of the orthographic projection of the convex end 220 along the height direction Y of the strip body 210 can be formed by at least one of a straight line or a curve. The projection shape of the convex end 220 on the isocenter plane corresponds to the orthographic projection shape of the convex end 220 along the height direction Y.

[0083] It is understandable that the convex end 220 can block part of the radiation beam emitted by the radiation source, so the projection shape of the convex end 220 on the isocenter plane can correspond to the shape of the outer contour of the convex end 220 .

[0084] In some examples, the shape of the orthographic projection formed by the convex end 220 along the height direction Y may include a curve. The curve may be a circular arc, an elliptical arc, a parabola, a trigonometric function curve, or a B-spline curve.

[0085] In some possible implementations, see Figures 1 to 7 As shown, along the width direction Z, the blade 200 includes a first side surface 201 and a second side surface 202 that are arranged opposite to each other. In the region from the first side surface 201 to the first center plane M, the cross-sectional area of ​​the convex end 220 gradually increases. In the region from the first center plane M to the second side surface 202, the cross-sectional area of ​​the convex end 220 gradually decreases.

[0086] The convex end 220 of the blade 200 of the embodiment of the present application has the largest cross-sectional area in the first central plane M, so that the radiation beam received by the area blocked by the blade 200 on the isocenter plane can be attenuated to within a standard range, reducing the possibility of the radiation beam irradiating normal tissue.

[0087] In some possible implementations, see Figures 1 to 7 As shown, along the height direction Y, the blade 200 includes a top surface 203 and a bottom surface 204 that are arranged opposite to each other. In the region from the top surface 203 to the second center plane N, the cross-sectional area of ​​the convex end 220 gradually increases. In the region from the second center plane N to the bottom surface 204, the cross-sectional area of ​​the convex end 220 gradually decreases.

[0088] The convex end 220 of the embodiment of the present application is protruding from one side of the strip-shaped body 210, and the convex end 220 of the blade 200 has the largest cross-sectional area in the second center plane N, and the positive projection of the convex end 220 along the height direction Y is a smooth line, thereby being helpful in improving the smoothness of the edge of the field shape and improving the accuracy of the field shape.

[0089] In some possible implementations, see Figures 1 to 7 As shown, the convex end 220 of the embodiment of the present application includes a transition surface 221 and an end 222. One end of the transition surface 221 is connected to the strip body 210, and the other end is connected to the end 222. The transition surface 221 is at least one of a plane, an arc surface or a curved surface.

[0090] In some examples, the transition surface 221 may be a curved surface to form a convex end 220 with a smooth transition, thereby facilitating a smoother edge of the field shape formed on the isocenter plane and facilitating improved accuracy of radiotherapy.

[0091] In some possible implementations, see Figures 1 to 7 As shown, along the width direction Z of the strip-shaped body 210 , the orthographic projection of the end portion 222 of the embodiment of the present application may be a curve.

[0092] In some possible implementations, see Figure 8 and Fig. 9 As shown, along the height direction Y, the multi-leaf collimator 10 with convex end blades includes at least two layers of collimator devices 100. The collimator device 100 includes two blade groups 110 arranged oppositely along the length direction X. The blade group 110 includes a plurality of blades 200. In the two blade groups 110 arranged oppositely, the convex ends 220 of the blades 200 in one blade group 110 are arranged oppositely to the convex ends 220 of the blades 200 in the other blade group 110. Along the width direction Z, the plurality of blades 200 are arranged side by side. There may be a gap between two adjacent blades 200. In two adjacent collimator devices 100, the gap between two adjacent blades 200 in the width direction Z of one layer is arranged correspondingly to the blades 200 of the other layer. Along the height direction Y, the projections formed by the blades 200 of the two adjacent layers of collimator devices 100 on the isocenter plane can jointly fit the shape of the edge of the tumor.

[0093] See also Figure 8 As shown, the collimator device 100 may include two blade groups 110. The two blade groups 110 are arranged opposite to each other to form a closed area. The blade group 110 includes a plurality of blades 200 arranged along the width direction Z. Before using the multi-leaf collimator 10 with convex end blades, it is necessary to adjust the position of the blades 200 so that the shape of the field aperture formed by the two blade groups 110 can match the target field shape.

[0094] It is understandable that in order to improve the stability of the blades 200 during movement, a gap is usually provided between two adjacent blades 200. However, the beam of radiation emitted by the radiation source is easy to leak through the gap and onto the isocenter plane. Therefore, in the present application, the blade 200 located in the upper layer can block the gap between the two adjacent blades 200 located in the lower layer, and the gap between the two adjacent blades 200 located in the upper layer can be set corresponding to the blades 200 located in the lower layer, so that the beam of radiation leaking through the upper collimator device 100 can be blocked by the blades 200 in the lower layer, which is conducive to reducing the leakage rate of the beam of radiation.

[0095] At the same time, since the projection of the convex end 220 of the present application on the isocenter plane is a curve or a structure formed by multiple straight lines and curves, a gap will be generated between two adjacent convex ends 220. The blades 200 located at the upper layer cooperate with the blades 200 located at the lower layer to more effectively fill the gap between the two adjacent convex ends 220, which is conducive to generating a curve with a higher degree of fit.

[0096] In some achievable embodiments, in two adjacent collimator devices 100 , the blades 200 located at the upper layer and the blades 200 located at the lower layer may be staggered along the width direction Z by a distance of half the width of the blade 200 .

[0097] In some examples, the distance between two adjacent leaves 200 in the leaf set 110 may be the same. In the multi-leaf collimator 10 having two layers of convex end leaves of the collimator device 100, the gap between two adjacent leaves 200 of the upper collimator device 100 may be set corresponding to the middle area of ​​the leaves 200 of the collimator device 100 located in the lower layer. It can be understood that the gap between two adjacent leaves 200 of the collimator device 100 located in the lower layer may correspond to the middle area of ​​the leaves 200 of the collimator device 100 located in the upper layer.

[0098] During the design of blade 200, see Figure 8 and Fig.11As shown, the blades 200 in the upper collimator device 100 and the blades 200 in the lower collimator device 100 can be staggered by a certain distance along the width direction Z. For example, this distance can be half of the width of the projection formed by the blade 200 on the isocenter plane. Therefore, the multi-leaf collimator 10 with convex end blades of the double-layer collimator device 100 can achieve a projection of the width of one blade 200 every half the width of the blade 200 on the isocenter plane, so that the gap between two adjacent blades 200 in the upper collimator device 100 can be blocked by the blade 200 in the lower collimator device 100, which can more effectively reduce the leakage rate of the ray beam.

[0099] Fig.10 The figure compares the field shape formed by the blades with convex ends in the embodiment of the present application with the field shape formed by the blades with rectangular ends in the related art. It is easy to see that for the same target area, the blades with convex ends have a better fitting effect. Fig.11 The multi-leaf collimator 10 with convex end leaves of one embodiment of the present application includes a double-layer collimator device 100 and a field shape formed by the leaves 200 having convex ends 220. It can be seen that the field shape formed by the double-layer collimator device 100 with the convex end 220 has a higher conformality.

[0100] For some examples, see Fig. 9 As shown, the multi-leaf collimator 10 with convex end blades may also include a three-layer collimator device 100. The three-layer collimator device 100 is arranged along the height direction Y of the strip-shaped body 210. In two adjacent collimator devices 100, the blades 200 located in the upper collimator device 100 may be staggered with the corresponding blades 200 located in the lower collimator device 100 by a certain distance. For example, this distance may be one-third of the width of the projection formed by the blade 200 on the isocenter plane. Therefore, the multi-leaf collimator 10 with convex end blades of the three-layer collimator device 100 can achieve a projection of the width of one blade 200 every one-third of the width of the blade 200 on the isocenter plane, thereby more effectively reducing the possibility of the radiation beam leaking through the gap between adjacent blades 200.

[0101] In addition, see Fig.11 and Fig.12 As shown, adding a layer of collimator device 100 on the basis of the double-layer collimator device 100 can also better fill the gap between two adjacent convex ends 220, thereby facilitating improving the accuracy of the edge of the field shape formed on the isocenter plane.

[0102] It should be noted that, during the design process of the blades 200 of the three-layer collimator device 100 , it is necessary to recalculate the design parameters of the blades 200 based on the position relationship between the position of each blade 200 in the three-layer collimator device 100 and the radiation source.

[0103] In summary, see Figure 8 , Fig. 9 , Fig.11 and Fig.12 As shown, the multi-leaf collimator 10 with convex end leaves may include a two-layer collimator device 100, or may include a three-layer collimator device 100. It can be understood that the multi-leaf collimator 10 with convex end leaves of the three-layer collimator device 100 has a higher fit than the multi-leaf collimator 10 with convex end leaves of the double-layer collimator device 100, and has a lower beam leakage rate.

[0104] It should be noted that, in the present application, the number of collimator devices 100 included in the multi-leaf collimator 10 with convex end leaves may be, but is not limited to, two or three.

[0105] In some possible implementations, see Fig.11 and Fig.12 As shown, along the length direction X, in two blade groups 110 arranged opposite to each other, the blades 200 are arranged one by one. At least one blade 200 of one blade group 110 can be connected to a blade 200 arranged opposite to each other in another blade group 110. In two adjacent collimator devices 100, the connection between two connected blades 200 of one layer is arranged corresponding to the blades 200 of the other layer.

[0106] In the collimator device, when a closed area is formed between two blade groups 110 arranged opposite to each other, a small gap may exist between the convex ends 220 of the two connected blades 200 to reduce the possibility of wear caused by repeated contact between the convex ends 220. At the same time, based on the structural shape of the convex ends 220 of the blades 200 of the present application, there is a gap when the convex ends 220 of the two opposite blades 200 are closed. Therefore, in the adjacent two-layer collimator device 100 of the present application, when the two blade groups 110 located in the upper layer are closed, the blade groups 110 located in the lower layer can be offset by a certain distance along the length direction X when they are closed, so that the blades 200 of the upper layer can block the gap between the convex ends 220 of the two connected blades 200 of the lower layer, and at the same time, the blades 200 of the lower layer can block the gap between the convex ends 220 of the two connected blades 200 of the upper layer, so as to reduce the probability of beam leakage.

[0107] In some possible implementations, see Fig.13As shown, in two adjacent collimator devices 100 , along the height direction Y, the projection of the upper blade assembly 110 may be located inside the projection of the lower blade assembly 110 .

[0108] In the embodiment of the present application, the projection shapes and sizes of the upper blade group 110 and the lower blade group 110 on the isocenter plane are the same.

[0109] In some examples, the top surface area of ​​the blade assembly 110 located at the lower layer may be larger than the bottom surface area of ​​the blade assembly 110 located at the upper layer.

[0110] In some examples, in the blade assembly 110, the top surface 203 of each blade 200 may be on the same horizontal plane. The bottom surface 204 of each blade 200 may be on the same horizontal plane.

[0111] In some possible implementations, see Fig.13 As shown, along the length direction X, the outer contour of the orthographic projection of the blade assembly 110 is a trapezoid, so that the convex end 220 of the blade 200 can be focused on the beam, thereby achieving side focusing of the blade 200.

[0112] The ray beam emitted by the radiation source may be in a pyramidal structure, that is, the longitudinal section of the ray beam is a trapezoidal structure. Along the length direction X, the outer contour of the orthographic projection of the blade assembly 110 of the present application is a trapezoidal structure that can match the cross-sectional shape of the ray beam to improve the focusing effect of the ray beam.

[0113] In some possible implementations, see Fig.13 and Fig.14 As shown, along the direction from the top surface 203 to the bottom surface 204 , the cross-sectional area of ​​the blade 200 gradually increases.

[0114] For some examples, see Fig.15 and Fig.16 As shown, the longitudinal section of the blade 200 may be trapezoidal in shape. The longitudinal section is perpendicular to the length direction X. The cross-sectional shapes of each blade 200 in each blade assembly 110 may not be completely the same, so that the projections of each blade 200 on the isocenter plane are the same shape.

[0115] In some examples, during the debugging process of the multi-leaf collimator 10 with convex end blades, the blade 200 can move along the length direction X of the strip body 210. In order to reduce the penumbra of the ray and achieve accurate dose delivery, one side end surface of the blade 200 of the multi-leaf collimator 10 with convex end blades is designed to be an arc-shaped, i.e., a convex end 220, to ensure that the blade 200 can be tangent to the incident ray at any position. The design of the convex end 220 of the blade 200 should also follow this scheme. Therefore, the blade 200 with the convex end 220 should integrate the arc end surface that focuses the incident ray and the convex projection design, that is, the above two conditions are met at the same time.

[0116] Fig.17 The configuration design method of the blade 200 that satisfies the above two conditions is demonstrated. In order to ensure the identity of the shape of the convex end 220, the design of the blade 200 of the present application can follow the following process.

[0117] S101, establishing a ray projection model, which can solve the projection cross-sectional shape of the blade 200 according to the position of the ray source, the position of the blade 200 and the projection shape of the blade 200 on the isocenter plane.

[0118] S102, determining basic parameters of the blade 200, and inputting the parameters of the blade 200 into the ray projection model to solve specific shape parameters of the blade 200. For example, the basic parameters of the blade 200 may be the length, height, projection width, and end face focusing design parameters of the blade 200.

[0119] S103, determining the position of the cross section projected on the convex end 220 of the blade 200 in the incident direction of the ray source at the point where the blade 200 is tangent to the ray beam according to the basic parameters and shape parameters of the blade 200;

[0120] S104, reversely solving the projected shape of the blade 200 at the tangent point height according to the projected cross-sectional shape, the ray source position, and the tangent point height, that is, the cross-sectional shape of the blade 200 at this position;

[0121] S105, repeating the above two steps to obtain the projected shapes at multiple cross-sectional positions to obtain the projected shapes at multiple cross-sectional positions;

[0122] S106 , arranging the cross sections at multiple heights in order of height positions, connecting the ends of all cross sections with smooth arc surfaces, and connecting the side surfaces of the cross sections with straight surfaces, and finally forming a three-dimensional structure of the blade 200 with a convex end 220 .

[0123] The shape of the projection can be an arc, an ellipse, a trigonometric function, a B-spline curve, etc. Among them, the shape of the optimal convex end 220 and its parameters need to be calculated according to the shape of the tumor. Since the multi-leaf collimator 10 with convex end leaves needs to treat different tumors during use, the shape of the convex end 220 should be optimized based on a tumor target database that can reflect clinical conditions. In order to accurately solve the optimal end shape, a method for calculating the shape of the optimal convex end 220 is added to the above leaf design method. Fig.18 The calculation method follows the following process.

[0124] S107, calculating the difference area of ​​the fitted target area under the protrusion degree of the convex end of different shapes by the integral method, and drawing a curve of the total difference area under each projection shape as a function of the protrusion degree.

[0125] When calculating the initialization, the two parameters are the projection curve category and the protrusion degree of the end shape of the blade 200. The projection curve category can be an arc, an ellipse, a trigonometric function, a B-spline curve, etc. The protrusion degree is the relative distance between the vertex of the projection shape of the blade 200 and the straight edge. The greater the distance, the greater the protrusion degree. Considering that the width of the blade 200 is different, and one side of the protruding shape is the width of the blade 200, the ratio of the protrusion distance to the width of the blade 200 is used as a measure of the protrusion degree of the blade 200. The protrusion degree of the blade 200 is between 0 times the blade width and 2 times the blade width, and the values ​​in between are taken in sequence.

[0126] The projection curve category of each leaf 200 and the position of the leaf 200 when forming a field at each convexity are calculated. It is determined that under the current projection curve category of the leaf 200, the field shape formed by the multi-leaf collimator 10 with convex end leaves has the highest conformity to the target area.

[0127] The total difference area between the field shape and the target shape at the position of the blade 200 is calculated. The total difference area includes the overfitting area where the convex end 220 of the blade 200 exceeds the edge of the target area and the underfitting area where the convex end 220 does not exceed the edge of the target area, and the total difference value is the sum of the two. Each difference area value is obtained by integrating the distance between the shape curve of the convex end 220 of the blade 200 and the tumor target area at each point on the blade 200 according to the arrangement direction of the blade 200.

[0128] Then, the curve of the total difference area under each projection shape and the protrusion degree is drawn to solve the optimal protrusion degree under the current shape.

[0129] S108, comparing the optimal results of different projection shapes, obtaining the optimal projection curve category and the optimal protrusion degree, and finally obtaining the optimal projection shape.

[0130] Fig.19The result of optimizing the shape of the convex end 220 of the blade 200 using a database pre-built according to the shapes of various tumor target areas in existing clinical manifestations is shown. The optimized shapes of the convex end 220 include an elliptical end, a trigonometric sin end, and a trigonometric cosh end. The ordinate represents the ratio of the sum of the overfitting and underfitting areas to the sum of the overfitting and underfitting areas of the straight end, and the abscissa represents the ratio of the protrusion of the convex end 220 of the blade 200 to the width of the blade 200. According to the calculation results, the three convex ends 220 can reduce the overfitting and underfitting areas, and the best result is the protrusion of the elliptical end on the blade 200. That is, when 0.4 times the blade width is used, the overfitting and underfitting areas are reduced by up to 31.2% compared to the straight end. It should be noted that the protrusion degree of the convex end 220 of the blade 200 and the conformal effect of the blade 200 are different on different data. Therefore, this result does not limit the optimal result of the present application. The result is calculated based on the tumor data of the pre-built database. Subsequent optimization can continue to be expanded to different databases on this basis.

[0131] It should be noted here that the numerical values ​​and numerical ranges involved in this application are approximate values. Due to the influence of the manufacturing process, there may be a certain range of errors, which can be considered negligible by those skilled in the art.

[0132] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, or it can be an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0133] In the description of the present application, it should be understood that the terms used such as “center”, “length”, “height”, “width”, “top”, “bottom”, “up”, “down”, “left”, “right”, “front”, “back”, “vertical”, “horizontal”, “inside”, “outside”, “axial”, “circumferential”, etc. to indicate directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred position or component must have a specific direction, structure and operation, and therefore should not be understood as limiting the present invention.

[0134] In the embodiments of the present application, the devices or elements referred to or implied must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present application. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise precisely and specifically specified.

[0135] The terms "first", "second", "third", "fourth", etc. (if any) in the description and claims of the embodiments of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example.

[0136] In addition, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements explicitly listed, but may include other steps or elements not explicitly listed or inherent to such process, method, product, or apparatus.

[0137] The term "plurality" in this article refers to two or more than two. The term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the previous and next associated objects are in an "or" relationship; in a formula, the character " / " indicates that the previous and next associated objects are in a "division" relationship.

[0138] It should be understood that the various numerical numbers involved in the embodiments of the present application are only used for the convenience of description and are not used to limit the scope of the embodiments of the present application.

[0139] It can be understood that in the embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

Claims

1. A multi-leaf collimator with convex end leaves, characterized in that: The blade includes a strip-shaped body and a convex end. Along the length direction of the strip-shaped body, the convex end is arranged at the end of the strip-shaped body. The convex end extends along the height direction of the strip-shaped body. Along the height direction, the cross-sectional area of ​​the convex end in the first center plane is the largest. Along the width direction of the strip-shaped body, the cross-sectional area of ​​the convex end in the second center plane is the largest.

2. The multi-leaf collimator with convex end leaves according to claim 1, characterized in that: Along the height direction, the shape of the orthographic projection of the convex end is formed by at least one of a straight line or a curve, and the projection shape of the convex end on the isocenter plane corresponds to the orthographic projection shape of the convex end along the height direction.

3. The multi-leaf collimator with convex end leaves according to claim 2, characterized in that: The curve includes an arc curve, an ellipse curve, a parabola, a trigonometric function curve or a B-spline curve, etc.

4. The multi-leaf collimator with convex end leaves according to claim 2, characterized in that: Along the width direction, the blade includes a first side surface and a second side surface that are oppositely arranged, and the cross-sectional area of ​​the convex end gradually increases in the region from the first side surface to the first central plane, and the cross-sectional area of ​​the convex end gradually decreases in the region from the first central plane to the second side surface; Along the height direction, the blade includes a top surface and a bottom surface that are relatively arranged. In the area from the top surface to the second center plane, the cross-sectional area of ​​the convex end gradually increases, and in the area from the second center plane to the bottom surface, the cross-sectional area of ​​the convex end gradually decreases.

5. The multi-leaf collimator with convex end leaves according to claim 2, characterized in that: Along the height direction, the multi-leaf collimator with the convex end blades includes at least two layers of collimator devices, the collimator devices include two blade groups arranged opposite to each other along the length direction, the blade groups include a plurality of blades, along the width direction, the plurality of blades are arranged side by side, and there is a gap between two adjacent blades, in two adjacent collimator devices, the gap between two adjacent blades of one layer is arranged corresponding to the blades of the other layer, and along the height direction, the projections formed by the blades of the two adjacent layers of the collimator devices on the isocenter plane are used to jointly fit the shape of the tumor edge.

6. The multi-leaf collimator with convex end leaves according to claim 5, characterized in that: In two adjacent collimator devices, along the height direction, the projection of the upper blade group on the isocenter plane is the same in shape and size as the projection of the lower blade group on the isocenter plane.

7. The multi-leaf collimator with convex end leaves according to claim 6, characterized in that: When the collimator device is double-layered, along the width direction, the blades located in the upper layer are staggered with the blades located in the lower layer by a distance of half the width of the blades to block the leakage of rays between adjacent blades and adjacent convex ends, or; When the collimator device has three layers, along the width direction, the blades located in the upper layer are staggered with the blades located in the lower layer by a distance of one third of the width of the blades to block radiation leakage between adjacent blades and adjacent convex ends.

8. The multi-leaf collimator with convex end leaves according to claim 7, characterized in that: When the collimator device is multi-layered, the shapes of the convex ends of the leaves located in different layers are not completely the same, and the convex ends of different shapes cooperate with each other to fit the shape of the tumor to the maximum extent.

9. A blade design method, characterized in that: include: S101, establishing a ray projection model; S102, determining basic parameters of the blade, and inputting the basic parameters into the ray projection model to solve the shape parameters of the blade; S103, determining the tangency point between the blade and the ray beam according to the basic parameters and the shape parameters, so as to determine the position of the projected cross section of the convex end of the blade in the incident direction of the ray source; S104, reversely solving the projected shape of the blade at the height of the tangent point according to the projected cross-sectional shape of the blade, the position of the ray source, and the height of the tangent point; S105, repeatedly executing S103 and S104 to obtain the projected shapes at multiple tangent point heights; S106, arranging the projected cross sections at the heights of the multiple tangent points in order of height position, connecting the ends of all the projected cross sections with smooth arc surfaces, and connecting the sides of the projected cross sections with straight surfaces to form a three-dimensional structure of the blade with the convex end.

10. The blade design method according to claim 9, characterized in that: include: S107, calculating the difference area of ​​the fitted target area under the protrusion degree of the convex end of different shapes by the integral method, and drawing a curve of the total difference area under each projection shape as a function of the protrusion degree; S108. Compare the optimal results of different projection shapes, obtain the optimal projection curve category and the optimal protrusion degree, and finally obtain the optimal projection shape.

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